JP3826174B2 - Imaging device - Google Patents

Description

ただしセンサー応答を表わす列ベクトルＶは
【０１０２】
【数２】

で与えられる。またカメラ特性を表わす行列Ｓは
【０１０３】
【数３】

で与えられる。ここで、行列Ｆは受光セルに配置された色フィルタの分光透過率を表わし、８つの色フィルタを用いるとして８行ｑ列からなる。たとえば３８０ｎｍから７８０ｎｍを１０ｎｍおきに取った場合、ｑ＝４１となる。また、行列Ｅは照明の分光分布を表わす対角行列であり、対角成分にｑ個の成分が並ぶ。
【０１０４】
さて、式（１）において、センサー応答Ｖの次元（ここでは８）と波長の次元ｑが同一であれば、カメラ特性行列Ｓは正則であり、逆行列Ｓ^-1によって
【０１０５】
【数４】

から被写体の分光反射率が求まる。
【０１０６】
しかし、本実施の形態のように、８種類の色フィルタを用いて３８０ｎｍから７８０ｎｍの帯域を１０ｎｍおきに量子化するとｑ＝４１となり、行列Ｓは正則とならない。このような場合はウィナー推定法が用いられる。今、被写体の真の分光反射率を行列Ｒ_real、推定された分光反射率を行列Ｒ_est、行列Ｓに対応する擬似逆行列をＧとすると、式（１）は
【０１０７】
【数５】

と表わされ、式（４）は
【０１０８】
【数６】

と表わされる。従って以下で与えられる行列Ｒ_realと行列Ｒ_estの最小自乗誤差εを最小化する推定行列Ｇを求めれば良い。
【０１０９】
【数７】

ここでｔは転置、＜＞はアンサンブル平均を表わす。εを最小にする推定行列はウィナー推定から次式で与えられる。
【０１１０】
【数８】

ここで、行列ρは相関行列を表わす。行列Ｒ_samplesと行列Ｖ_samplesは相関行列ρを算出するためのサンプルデータで、行列Ｒ_samplesはサンプルの分光反射率行列、Ｖ_samplesはＲ_samplesに対する信号値を表わし、短波長成分色信号処理部１０８と長波長成分色信号処理部１０９の出力信号に対応する。
【０１１１】
第四に、測色値変換部１１２とセル単位明度信号置換部１１４について、図５を用いて詳細に説明する。図５は、実施の形態１にかかる、測色変換部、照明分光情報記憶部、明度信号変換部、セル単位明度置換部の動作を説明する図である。
【０１１２】
図５に示すように、測色値変換部１１２は、被写体分光情報推定部１１０が縦２セル、横２セルのブロック単位で推定した被写体の分光情報と照明分光情報記憶部１１３から供給される照明の分光情報から次式に用いてブロック単位でＣＩＥＸＹＺ三刺激値を算出する。
【０１１３】
【数９】

ここで、ｒ_hは波長ｈ番目の被写体の分光反射率を表わす。測色値変換部１１２は、ＣＩＥＸＹＺ三刺激値をさらに輝度成分と色味成分に分離された測色値、たとえば、式（１０）を用いてＣＩＥＬＡＢ値などに変換する。
【０１１４】
【数１０】

ここで、Ｘ_n、Ｙ_n、Ｚ_nは基準白色のＣＩＥＸＹＺ三刺激値を表わす。ただし、輝度成分は式（１０）にあるような視覚系の明るさ間隔に対して比例的な関係を持つ明度信号に変換する。一般に、式（９）で与えられる輝度値は視覚系の明るさ間隔に対して線形関係が成り立たず、式（１０）に示すような１／３乗程度の指数関数で輝度値を変換すると視覚系の明るさ間隔と線形関係が成立すると言われている。
【０１１５】
一方、明度信号変換部１０５は輝度信号生成部１０４で受光セル単位に算出された輝度信号Ｙを式（１０）を用いて明度信号Ｌ^*に変換する。測色値変換部１１２が縦２セル、横２セルのブロック単位で測色値を算出するのに対し、明度信号変換部１０５はセル単位で明度信号Ｌ^*を算出する。
【０１１６】
そこで、セル単位明度信号置換部１１４は、測色値変換部１１２から出力される測色値のうち、明度成分Ｌ^*のみ、明度信号変換部１０５からの出力に置き換える。
【０１１７】
前述したように、視覚系は輝度変調に対する解像力が高いため、縦２セル、横２セルのブロック単位で算出されたＣＩＥＬＡＢ値の明度成分Ｌ^*のみを色成分ａ^*とｂ^*に対して縦方向、横方向それぞれで２倍の解像度に変換する。
【０１１８】
ところで、照明分光情報記憶部１１３に格納する照明の分光分布を、被写体が撮影された環境の照明と別の分光分布に入れ替えれば、照明変換が容易に行える。
【０１１９】
たとえば、再現画像はプリンタで紙に印刷されるとして、被写体は色温度４０００Ｋ程度のタングステンランプで照明されていて、再現画像は６５００Ｋ程度の昼光ランプで観察する場合を考える。被写体の撮影の視環境下（つまり４０００Ｋタングステンランプ）で定義されるＣＩＥＸＹＺ三刺激値で出力したい場合は、式（９）のｅ_hに４０００Ｋタングステンランプの分光分布を代入すればいい。プリントを観察する視環境下（つまり６５００Ｋ昼光ランプ）で定義されるＣＩＥＸＹＺ三刺激値で出力したい場合は、式（９）のｅ_hに６５００Ｋ昼光ランプの分光分布を代入すればいい。上記のような照明変換は、マルチバンドカメラ特有の機能であり、マルチバンドカメラは被写体の分光反射率を算出できるためである。測色値情報をＣＩＥＸＹＺ三刺激値ベースで持ち、分光情報を持たない３バンドカメラと大きく差別化される特徴である。
【０１２０】
このように、測色値変換部１１２が照明分光情報記憶部１１３に保持した照明の分光情報を用いて被写体の測色値を算出することで、測色値を被写体の分光情報と照明の分光情報から算出できる。
【０１２１】
第五に、原色変換部１１６について詳細に説明する。原色変換部１１６は測色値を映像表示デバイスに依存した信号に変換する。測色値とデバイス依存信号の関係は、ディスプレイの原色点の測色値で決まる。たとえばＩＴＵ−Ｒ Ｒｅｃ．ＢＴ．７０９−３では測色パラメータとして３原色の色度値を定めている。すなわち、Ｒ原色は（ｘ，ｙ）＝（０．６４，０．３３）、Ｇ原色は（ｘ，ｙ）＝（０．３０，０．６０）、Ｂ原色は（ｘ，ｙ）＝（０．１５，０．０６）であり、表示色の輝度値と比例関係にある輝度リニアデバイスドライブ信号Ｒ、Ｇ、ＢとＣＩＥＸＹＺ三刺激値との関係は以下で与えられる。
【０１２２】
【数１１】

ここで、Ｘ_R、Ｙ_R、Ｚ_RはＲ原色のＣＩＥＸＹＺ三刺激値を表わし、同様にＸ_G、Ｙ_G、Ｚ_GはＧ原色のＣＩＥＸＹＺ三刺激値を、Ｘ_B、Ｙ_B、Ｚ_BはＢ原色のＣＩＥＸＹＺ三刺激値を表わす。ＣＩＥＸＹＺ三刺激値とｘｙ色度座標の関係は
【０１２３】
【数１２】

で与えられるために、式（１１）はＲ原色の色度座標（ｘ_R，ｙ_R）、Ｇ原色の色度座標（ｘ_G，ｙ_G）、Ｂ原色の色度座標（ｘ_B，ｙ_B）を用いて以下のように書き換えられる。
【０１２４】
【数１３】

以上、原色変換部１１６は、式（１３）によってＣＩＥＸＹＺ三刺激値を輝度リニアデバイスドライブ信号Ｒ、Ｇ、Ｂに変換する。
【０１２５】
なお、本発明は映像表示デバイスの原色数を限定するものではなく、式（１１）と式（１３）の３原色は任意数に拡張可能である。
【０１２６】
第六に、ガンマ補正部１１７について詳細に説明する。現在、流通しているデバイス依存のＲＧＢ信号は、ＮＴＳＣ方式の概念を周到するＣＲＴディスプレイのガンマ補正処理が施されている。ＣＲＴディスプレイは、表示管や信号処理系などの総合的入出力特性として、デバイスドライブ信号と発光輝度の関係が２．２乗の指数関数で表わされる。これがいわゆるガンマ特性である。そこで、デバイスドライブ信号と発光輝度の関係が線形になるように、予め送信側で１／２．２乗の指数関数変換を施し、ＣＲＴディスプレイのガンマ特性を相殺するように、いわゆるガンマ補正を施してＲ信号、Ｇ信号、Ｂ信号を送出する。ガンマ補正部１１７は、式（１４）で輝度リニアデバイスドライブ信号Ｒ、Ｇ、Ｂをガンマ補正済のデバイスドライブ信号Ｒ'、Ｇ'、Ｂ'に変換する。
【０１２７】
【数１４】

なお、本発明は映像表示デバイスの原色数を限定するものではなく、式（１４）の３原色は任意数に拡張可能である。
【０１２８】
このように、ガンマ補正部１１７を具備することで、撮像素子の受光セル単位で明度が置換された測色値を表示デバイスのガンマ補正処理を含んだ輝度・色差信号に変換できる。
【０１２９】
第七に、輝度・色差信号変換部１１９について詳細に説明する。デバイスドライブ信号Ｒ'、Ｇ'、Ｂ'は、輝度・色差信号変換部１１９において様々な伝送フォーマットに対応させるために輝度・色差信号に変換される。たとえばＩＴＵ−Ｒ Ｒｅｃ．ＢＴ．７０９−３に従う場合は、式（１５）によってデバイスドライブ信号Ｒ'、Ｇ'、Ｂ'が輝度・色差信号に変換される。
【０１３０】
【数１５】

このように、輝度・色差信号変換部１１９を具備することで、撮像素子の受光セル単位で明度が置換された測色値の輝度線形性を保ったまま、輝度・色差信号に変換できる作用を有する。
【０１３１】
なお、本発明は、デバイスドライブ信号Ｒ'、Ｇ'、Ｂ'を輝度・色差信号へ変換する方式に対して制限を与えるものではなく、伝送フォーマットに応じて自由に設定できることを特筆しておく。
【０１３２】
たとえば、Ｒバンドの寄与率を０．３０、Ｇバンドの寄与率を０．５９、Ｂバンドの寄与率を０．１１とした線形和で輝度信号を算出することで、ＥＩＡ−ＲＳ １７０Ａ方式に従わせることができ、ＥＩＡ−ＲＳ １７０Ａ方式のデコーダを有する映像表示デバイスで正確な色再現を可能にする。
【０１３３】
また、Ｒバンドの寄与率を０．２９９、Ｇバンドの寄与率を０．５８７、Ｂバンドの寄与率を０．１１４とした線形和で輝度信号を算出することで、ＳＭＰＴＥ １７０Ｍ方式のデコーダを有する映像表示デバイスで正確な色再現を可能にする。
【０１３４】
最後に、走査方式の違いに対応する方法とデバイスドライブ信号用ラインメモリ１１８、輝度・色差信号用ラインメモリ１２０について詳細に説明する。一般に映像方式には１走査ラインおきに飛び越し走査を行うインタレース方式と飛び越しなしに走査ライン順に走査を行うプログレッシブ方式がある。本発明では、短波長成分色信号処理部１０８と長波長成分色信号処理部１０９が受光セル単位で縦２セル、横２セルを単位ブロックとしたブロック単位で測色値を算出する。従って、走査ライン方向に見た場合、２ライン分の測色値が１回の動作で求められる。そこで、プログレッシブ方式の場合は、２ライン目の測色値データを保持しておいて、走査タイミングに合わせて、保持しておいた２ライン目の測色データを送出する必要がある。
【０１３５】
図１におけるデバイスドライブ信号用ラインメモリ１１８は、取り込んだ被写体の色情報をデバイスドライブ信号形式で保持し、デバイスドライブ信号用送信機１２１からの走査タイミングに合わせた読み出し指示に従って保持したデバイスドライブ信号を出力する。
【０１３６】
同様に、輝度・色差信号用ラインメモリ１２０は、取り込んだ被写体の色情報を輝度・色差信号形式で保持し、輝度・色差信号用送信機１２２からの走査タイミングに合わせた読み出し指示に従って保持した輝度・色差信号を出力する。
【０１３７】
またインタレース方式の場合は、ラインメモリに保持することなく取得された被写体の分光情報をそのまま出力すればいい。すなわち、図３に示すように、被写体の分光反射率は縦２セルずつ取得される。そこで、インタレース走査が奇数ラインを走査中でも偶数ラインを走査中でも、被写体分光情報推定部１１０は同一の分光反射率を出力する。このため、測色値変換部１１２は奇数ラインでも偶数ラインでも同じ測色値を出力し、ラインメモリにデータを保持しておく必要はない。
【０１３８】
ただし、被写体の分光反射率を推定する単位ブロックの縦方向のセル数が３以上の場合は、プログレッシブ方式とインタレース方式の両走査方式において、データを保持しておく必要がある。プログレッシブ方式の場合は、単位ブロックの縦方向のセル数をｎとすると（ｎ−１）ライン分のラインメモリを必要とする。インタレース方式の場合は、（ｎ−１）／２の商にあたるライン分のラインメモリを必要とする。ラインメモリに保持された信号値は、送信機から指示された読み出しタイミングに応じて出力される。
【０１３９】
このように、単位ブロックが縦ｎセルから構成されている際には、単位ブロック内の（ｎ−１）ラインに相当する外部出力信号をラインメモリに記憶し、単位ブロック内の第２ライン以降の出力はラインメモリから撮像装置の外部へ出力することで、受光セル単位でｎライン分同時に生成されるマルチバンド画像のうち、第１ラインはラインメモリを介さず出力し、第２ライン以降の（ｎ−１）ラインは画像走査の同期に合わせてラインメモリから出力して、様々な走査方式に対応できる。
【０１４０】
一方、被写体の分光情報を推定する単位ブロックが走査ラインごとに移動する場合は最小限の構成でプログレッシブ方式とインタレース方式に対応できる。図６は、実施の形態１にかかるデバイスドライブ信号用ラインメモリと、輝度・色差信号用ラインメモリの動作を説明する図である。図６は、図３と同様に縦２セル、横２セルを単位ブロックとして被写体の分光情報を推定するケースである。図６（ａ）は、実施の形態１にかかるデバイスドライブ信号用ラインメモリと、輝度・色差信号用ラインメモリの画像の第１走査ライン走査時における動作を表わした図であり、図６（ｂ）は、実施の形態１にかかるデバイスドライブ信号用ラインメモリと、輝度・色差信号用ラインメモリ画像の、第２走査ライン走査時の動作を表わした図である。
【０１４１】
撮影装置が画像の第１走査ラインを走査している場合、図６（ａ）に示すように、短波長成分撮像素子１０６と長波長成分撮像素子１０７は、素子の第１走査ラインと第２走査ラインがアクティブとなり、２ライン分の信号が同時に被写体分光情報推定部１１０に出力されて、被写体の分光情報を２ライン単位で推定する。そこで、撮影装置は、第２走査ラインの出力信号を、画像の走査が第２走査ラインに入るまで保持する必要があり、分光情報は測色値に変換された後、１ライン分のラインメモリ６０１（図１中のデバイスドライブ信号用ラインメモリ１１８および輝度・色差信号用ラインメモリ１２０に相当）に第２走査ラインの測色値が保存される。画像の走査が第２走査ラインに移ったら、図６（ｂ）に示すように、短波長成分撮像素子１０６、長波長成分撮像素子１０７、被写体分光情報推定部１１０とは関係なく、ラインメモリ６０２（実体はラインメモリ６０１と同一。）から、すでに計算済の出力信号を外部出力する。
【０１４２】
図７は、被写体の分光情報推定における単位ブロックの位置を画像の走査位置に合わせて、１ラインずつ移動する場合である。図７（ａ）は、実施の形態１にかかるデバイスドライブ信号用ラインメモリと、輝度・色差信号用ラインメモリの画像の、第１走査ライン走査時の動作を表わした図であり、図７（ｂ）は、実施の形態１にかかるデバイスドライブ信号用ラインメモリと、輝度・色差信号用ラインメモリ画像の、第２走査ライン走査時の動作を表わした図である。
【０１４３】
画像の第１走査ライン走査時は、図６（ａ）と同様に、短波長成分撮像素子１０６と長波長成分撮像素子１０７の第１走査ラインと第２走査ラインがアクティブとなり、２ライン分の信号が同時に被写体分光情報推定部１１０に出力されて、被写体の分光情報を２ライン単位で推定する。分光情報は測色値に変換されて、そのまま外部へ出力される。画像の走査が第２走査ラインに移ると、図７（ｂ）に示すように、短波長成分撮像素子１０６と長波長成分撮像素子１０７は、素子の第２走査ラインと第３走査ラインがアクティブとなり、２ライン分の信号が同時に被写体分光情報推定部１１０に出力されて、被写体の分光情報を２ライン単位で推定する。引き続き、分光情報は測色値に変換されて、そのまま外部へ出力される。
【０１４４】
図７に示すように、分光推定を行う撮像素子上の単位ブロックの第１ラインが、画像走査の走査ラインと一致するように移動すれば、図６に示すようなラインメモリが必要なくなる。また、図７で推定される分光情報は、撮像素子を１ラインずつ移動していくため、２ラインごとに分光推定を行う図６より、推定精度が高くなる利点がある。
【０１４５】
つまり、図６の場合、奇数走査ライン、偶数走査ラインの順で隣接する２ラインは同一の分光情報を持ち、たとえば図６の隣接するセル６０３とセル６０４は同一の分光情報Ｒ₁₁を持つ。
【０１４６】
一方、図７の場合、セル６０４と同一位置にあるセル７０１は、画像の第１走査ラインを走査時図７（ａ）には、分光情報Ｒ₁₁を持つが、画像の第２走査ラインを走査時図７（ｂ）には、分光情報Ｒ₂₁に書き換えられる。分光情報Ｒ₂₁は撮像素子の第２ライン、第３ラインで取得した被写体情報であり、撮像素子の第１ライン、第２ラインから取得された被写体情報Ｒ₁₁とは異なる。
【０１４７】
以上、分光推定を行う撮像素子上の単位ブロックの第１ラインが、画像走査の走査ラインと一致するように移動することで、単位ブロック固定の場合よりも正確な分光推定が可能になるが、図５において、すでに詳細に説明を行ったセル単位明度信号置換部１１４との組み合わせで、色推定精度がさらに向上することを追記しておく。
【０１４８】
なお、図６と図７では分光推定を行う単位ブロックを縦２セル、横２セルを例にとって説明したが、本発明は単位ブロックのセル数に制限されるものではなく、任意サイズの単位ブロックで実施可能であることを特筆しておく。
【０１４９】
また、デバイスドライブ信号用送信機１２１と輝度・色差信号用送信機１２２は任意の伝送フォーマットを適応可能であり、ＩＴＵ−ＲやＳＭＰＴＥのテレビジョン、ＶＴＲ、ディスク記録フォーマット等の標準規格や、多くのデジタルカメラで採用されているｓＲＧＢ信号など、任意に対応できる。
【０１５０】
以上、実施の形態１によって、視覚系の解像力の高い明度成分情報を前記輝度撮像素子で高精細に取得し、同時に短波長成分撮像素子と長波長成分撮像素子から取得された測色値の明度成分のみを輝度撮像素子からの明度成分情報で撮像素子の受光セル単位に置換することによって、短波長成分撮像素子と長波長成分撮像素子の受光セルに具備された色フィルタの種類より少ない２つの撮像素子でマルチバンド画像を同時に撮影でき、動きの速い被写体のスチル画像撮影や動画撮影が可能になる。
【０１５１】
また、実施の形態１は、短波長成分撮像素子１０６および長波長成分撮像素子１０７が、互いに異なり、かつ単位ブロック内のすべての色フィルタを組み合わせるとダイクロイックミラー２１０が分割した短波長側および長波長側の光の波長帯域をカバーする分光透過率分布を持つ受光セルからなる単位ブロックを持つので、ダイクロイックミラー２１０が分割した短波長成分および長波長成分の光を無駄なく受光し、視覚系の解像力の低い色成分情報を単位ブロックごとで取得することにより、１つに撮像素子で複数のマルチバンド画像を撮影できる。
【０１５２】
さらに、実施の形態１は、単位ブロックが、縦２セル、横２セルからなるので、縦２セル、横２セルの単位ブロックごとに被写体の分光情報を推定できる。この結果、１つの撮像素子で単位ブロックごとに４つのマルチバンド画像が同時に撮影できる作用を有する。よって、短波長成分撮像素子１０６および長波長成分撮像素子１０７の２つの撮像素子を使用することで、４×２の８バンドの画像が同じに撮影できる。
【０１５３】
また、実施の形態１は、単位ブロックの縦方向の位置が、単位ブロックの１ライン目が画像走査の走査ラインと一致するように決定されているので、撮像装置の出力信号をラインメモリへ一時的に保持することなくストリーム形式で出力でき、かつ被写体の分光情報を走査ラインごとに緻密の推定できる。
【０１５４】
また、実施の形態１は、色分解光学系１０２を、入射光を２つの光路に分割するハーフミラー２０３を備えた第１光学プリズム２０２と、第１光学プリズム２０２で分割された一方の光の短波長成分のみ反射するダイクロイックミラー２１０を備えた第２光学プリズム２０９と、第２光学プリズム２０９で透過した長波長成分を透過する第３光学プリズム２１６と、エアギャップ２０８と、から構成した。これにより、輝度成分と短波長、長波長の２つの色成分に分割する色分解光学系１０２を３つの光学プリズムの容積分だけに小型化できる。また、ここで着目すべき点に、色分解光学系１０２が、従来のＲＧＢからなる色分解光学系等と同様に３つの光学プリズムから構成されている点がある。つまり、本実施の形態の色分解光学系１０２は、従来の色分解光学系を少し改良するだけで作成できる。よって、本実施の形態の色分解光学系１０２は、既存の材料から作成できるので、既存の撮像装置に適用することが容易である。
【０１５５】
また、実施の形態１は、第２光学プリズム２０９は、長波長成分がプリズム内部からプリズム外部へ出力される境界面に赤外吸収フィルタ２１５を具備することで、赤外光に感度を持つ撮像素子からのノイズを簡単な構成で抑制できる。
【０１５６】
（実施の形態２）
以下、本発明の実施の形態２にかかる撮像装置であるマルチバンドビデオカメラについて説明する。まず、実施の形態２における３つの撮像素子でマルチバンド画像を同時に撮影するマルチバンドビデオカメラのシステムについて図８を用いて説明する。図８は、実施の形態２における３つの撮像素子でマルチバンド画像を同時に撮影するマルチバンドビデオカメラのシステム構成図である。図８と図１の相違点は以下の２点で、その他は同一の構成を持ち、かつ同一の動作、機能を有する。
【０１５７】
第一の相違点は、図８には図１の明度信号変換部１０５がない点である。第二の相違点は、図１のセル単位明度信号置換部１１４がセル単位測色値スケーリング部８０１に変更されている点である。
【０１５８】
図１のセル単位明度信号置換部１１４は、図５で詳細に説明したように、撮像素子の受光セル単位で、測色値変換部１１２からの測色値の明度のみを明度信号変換部１０５からの明度信号で置換した。一方、図８のセル単位測色値スケーリング部８０１は、図８の測色値変換部８０２から供給された測色値を、輝度信号生成部８０３の輝度信号を用いてスケーリングする。
【０１５９】
次に、図９を用いてセル単位測色値スケーリング部８０１の動作を詳細に説明する。図９は図５と同様に、被写体の分光推定の単位ブロックを、縦２セル、横２セルとした場合である。測色値変換部８０２は、図８の被写体分光情報推定部８０４が供給する被写体の分光反射率ｒ_hと図８の照明分光情報記憶部８０５が供給する照明の分光分布ｅ_hから式（９）を用いてＣＩＥＸＹＺ三刺激値を算出する。測色値変換部８０２の出力（Ｘ'Ｙ'Ｚ'）は、セル単位測色値スケーリング部８０１に与えられ、輝度生成部８０３で生成されたセル単位の輝度信号Ｙを用いて式（１６）のスケーリング処理が施される。
【０１６０】
【数１６】

従って、セル単位測色値スケーリング部８０１は、分光情報推定の単位ブロックごとに算出された相対的な測色値情報（Ｘ'Ｙ'Ｚ'）を、セル単位のスケーリング処理を用いて、セル単位で絶対的測色値情報（ＸＹＺ）に変換する機能を有する。
【０１６１】
図８の原色変換部８０６は、セル単位測色値スケーリング部８０１の出力であるＣＩＥＸＹＺ三刺激値を式（１３）を用いて、輝度リニアデバイスドライブ信号Ｒ、Ｇ、Ｂに変換する。
【０１６２】
以上、実施の形態２によって、視覚系の解像力の高い輝度成分情報を高精細に保ちつつ、短波長成分撮像素子と長波長成分撮像素子の受光セルに具備された色フィルタの種類より少ない２つの撮像素子でマルチバンド画像を同時に撮影でき、動きの速い被写体のスチル画像撮影や動画撮影が可能になる。
【０１６３】
（実施の形態３）
次に、本発明の実施の形態３にかかる撮像装置であるマルチバンドビデオカメラについて説明する。
【０１６４】
図１０は、本発明の実施の形態３における３つの撮像素子でマルチバンド画像を同時に撮影するマルチバンドビデオカメラのシステム構成を示し、図１と比較しながら、以下に説明する。図１と図１０の相違点は以下の１点で、その他は同一の構成を持ち、かつ同一の動作、機能を有する。図１０と図１との相違点は、図１０には図１のガンマ補正部１１７がない点である。
【０１６５】
ガンマ補正は、図１で詳細に説明したように、表示デバイスが持つデバイスドライブ信号と表示色の輝度との非線形特性を線形化するものである。表示デバイスに特別な処理回路を搭載することなく、送信側の処理のみで対応できるため、受信側の端末機器の簡素化、廉価化に有効である。
【０１６６】
しかし、近年、半導体部品を中心とする電子機器の高性能化とコストダウンが大幅に達成され、受信端末機に様々な処理機能を持たせることが可能になってきた。特に、計算機端末としての表示デバイスは、ビジネスグラフィックスやコンピュータグラフィックスを作成する映像表示装置として活用され、表示デバイス自身で輝度リニア信号を発生する機能を有するものが増えてきた。インターネットを中心とする放送と通信の融合は、逆ガンマ特性を持った信号で映像を表示するテレビジョンと輝度リニア信号で映像を表示する計算機ビジュアル端末の２つの機能を持つ映像表示装置の需要を作り上げた。
【０１６７】
このため、受信端末が自身でガンマ補正機能を持っている場合、送信側はガンマ補正を施す必要がなくなる。実施の形態３は、ガンマ補正を加えずに映像信号を出力する撮像装置であり、表示デバイス自身でガンマ補正を実行する計算機ビジュアル端末等に、正確な色情報を供給できる。
【０１６８】
以上、実施の形態３によって、視覚系の解像力の高い輝度成分情報を高精細に保ちつつ、短波長成分撮像素子と長波長成分撮像素子の受光セルに具備された色フィルタの種類より少ない２つの撮像素子でマルチバンド画像を同時に撮影でき、動きの速い被写体のスチル画像撮影や動画撮影が可能になり、かつガンマ補正の必要がない画像デバイスにガンマ補正なしの色信号を供給できる。
【０１６９】
（実施の形態４）
以下、本発明の実施の形態４にかかる撮像装置であるマルチバンドビデオカメラについて説明する。図１１は、本発明の実施の形態４における２つの撮像素子でマルチバンド画像を同時に撮影するマルチバンドビデオカメラのシステム構成を示し、図１と比較しながら、以下に説明する。図１と図１１の相違点は以下の３点で、その他は同一の構成を持ち、かつ同一の動作、機能を有する。
【０１７０】
第一の相違点は、色分解光学系にあり、図１の色分解光学系１０２は撮像レンズ１０１から入射した被写体からの光を３つの光路に分けるのに対し、図１１の色分解光学系１１０１は撮像レンズ１１０２から入射した被写体からの光を２つの光路に分け、輝度撮像素子１１０３と後述する色成分撮像素子１１０４に光を分配する点である。
【０１７１】
第二の相違点は、被写体の分光情報を撮像する撮像素子で、図１では短波長成分撮像素子１０６と長波長成分撮像素子１０７の２つの撮像素子で被写体の分光情報を推定するのに対し、図１１では色成分撮像素子１１０４の１つの撮像素子で被写体の分光情報を推定する点である。
【０１７２】
第三の相違点は、撮像素子が１つになったことに伴う信号処理部の違いで、色成分撮像素子１１０４からの信号は色成分色信号処理部１１０５へ入力し、被写体分光情報推定部１１０６での分光推定は、色成分色信号処理部１１０５からの出力のみで実行される点である。
【０１７３】
次に、図１２を用いて、色分解光学系１１０１について詳細に説明する。色分解光学系１１０１内部には、撮像レンズ１１０２からの入射光１２０３を２つの光路に分割するハーフミラー１２０１が設けられている。ハーフミラー１２０１により分割された第１の光路の光は、ハーフミラー１２０１の反射光１２０５である。ハーフミラー１２０１は、反射光１２０５が輝度撮像素子１１０３に垂直に入射されるように配置されている。ハーフミラー１２０１により分割された第２の光路の光は、ハーフミラー１２０１の透過光１２０４である。ハーフミラー１２０１は、透過光１２０４が色成分撮像素子１１０４に垂直に入射されるように配置されている。
【０１７４】
このようにハーフミラー１２０１により、入射光１２０３は、透過光１２０４と反射光１２０５に分割され、透過光１２０４は色成分撮像素子１１０４に入射し、反射光１２０５は輝度撮像素子１１０３に入射する。
【０１７５】
また、ハーフミラー１２０１には波長選択性はなく、ハーフミラー１２０１によって分割された光１２０４と光１２０５とは同一の分光分布を持つ。
【０１７６】
また、色分解光学系１１０１の内部の、ハーフミラー１２０４に対して色成分撮像素子１１０４側、つまり、透過光１２０４の進む方向には、赤外吸収フィルタ１２０２が色成分撮像素子１１０４と平行に設けられている。これにより、透過光１２０４は、色成分撮像素子１１０４に入射される前に、赤外吸収フィルタ１２０２によりノイズを除去される。
【０１７７】
次に色成分撮像素子１１０４と被写体分光情報推定部１１０６について詳細に説明する。図１３（ａ）は色フィルタの配列を説明する図、図１３（ｂ）は画素単位で見た色信号の配列を説明する図である。
【０１７８】
色成分撮像素子１１０４はｆ₁からｆ₉で示される９種類の色フィルタを縦３セル、横３セルのブロック単位で具備する。９種類の色フィルタｆ₁からｆ₉は互いに異なる分光透過率分布を持ち、たとえば図１４に示すように９つで可視域（図１４では３８０ｎｍから７８０ｎｍ）をカバーする関係を持つ。つまり可視域全体の光を９つの色フィルタで分担して受光する。
【０１７９】
上述したように、被写体の分光推定には、少なくとも５バンド分の情報が必要である。このため、縦横同じ数の正方形の単位ブロックで、５バンド分以上のバンドを形成するには、図１３に示すような、縦３セル、横３セルが最小構成となる。
【０１８０】
そして、被写体分光情報推定部１１０６は、色フィルタｆ₁からｆ₉の９つの信号をもとに被写体の分光情報を推定する。従って、被写体分光推定部１１０６は、分光情報を縦３セル、横３セルのブロック単位で推定し、算出する。
【０１８１】
図１の２つの撮像素子で分光推定を行う構成に比べて、色成分の空間解像度は１／３に落ちるが、撮像素子が１つであり、かつ図１２に示したように、色分解光学系の構成も簡素化されるため、サイズやコスト面で大きな利点を持つ。 また、図７ですでに説明したように分光推定の単位ブロックを画像走査に合わせて移動すれば、解像度低下の影響を抑えられる。
【０１８２】
以上、実施の形態４によって、視覚系の解像力の高い輝度成分情報を高精細に保ちつつ、色撮像素子の受光セルに具備された色フィルタの種類より少ない１つの撮像素子でマルチバンド画像を同時に撮影でき、動きの速い被写体のスチル画像撮影や動画撮影が可能になる作用を有する。
【０１８３】
なお、実施の形態４の明度信号変換部１０５を無くし、セル単位明度信号置換部１１４をセル単位測色値スケーリング部８０１に置き換えた形態であっても良い。この構成により、視覚系の解像力の高い輝度成分情報を輝度撮像素子１１０３で高精細に取得し、同時に色成分撮像素子１１０４から取得した測色値を輝度撮像素子１１０３からの輝度成分情報で撮像素子の受光セル単位にスケーリングできる。この結果、色成分撮像素子１１０４の受光セルに具備された色フィルタの種類より少ない１つの撮像素子でマルチバンド画像を同時に撮影でき、動きの速い被写体のスチル画像撮影や動画撮影が可能になる。
【０１８４】
（実施の形態５）
以下、本発明の実施の形態５にかかる撮像装置であるマルチバンドビデオカメラについて図１５を用いて説明する。図１５は、実施の形態５における３つの撮像素子でマルチバンド画像を同時に撮影するマルチバンドビデオカメラのシステム構成図である。すでに、説明した部分と同一の部分については、同一の符番を付与し説明を省略する。
【０１８５】
実施の形態５と実施の形態１との相違点は、輝度・色差信号変換部１１９が明度・色差信号変換部１５０１に、輝度・色差信号用ラインメモリ１２０が明度・色差信号用ラインメモリ１５０２に、輝度・色差信号用送信機１２２が明度・色差信号用送信機１５０３になっている点である。
【０１８６】
明度・色差信号変換部１５０１は、セル単位明度信号置換部１１４が、撮像素子の受光セルごとに算出した測色値を明度成分と色差成分に変換する。具体的には、明度・色差信号変換部１５０１は、まず、映像表示デバイスのガンマ特性を相殺するデバイスドライブ信号あるいは輝度リニアデバイスドライブ信号の線形和で輝度信号を生成する。次に、明度・色差信号変換部１５０１は、デバイスドライブ信号あるいは輝度リニアデバイスドライブ信号の構成要素のうち、線形和において輝度信号生成への寄与率の最も大きい要素を除いた全ての要素のそれぞれから輝度信号を差し引いた差分値を色差信号とし、輝度信号を指数関数によって明度信号に変換し、明度信号と色差信号を出力する。
【０１８７】
また、明度・色差信号用ラインメモリ１５０２および明度・色差信号用送信機１５０３は、実施の形態１の輝度・色差信号用ラインメモリ１２０および輝度・色差信号用送信機１２２が輝度信号を扱うのに対し、明度信号を扱うようにしたものであり、その他の動作については同一である。
【０１８８】
以上説明したように、実施の形態５によれば、撮像素子の受光セル単位で明度が置換された測色値を、明度線形性を保ったまま、明度・色差信号に変換できる作用を有する。また、映像表示デバイスに特別な処理部を設けることになくデバイスドライブ信号と発光色の明度の線形性を確保し、かつデバイスドライブ信号よりも帯域の小さい明度・色差信号での信号伝送を可能にする作用を有する。
【０１８９】
なお、実施の形態５では、実施の形態１を変形した形態で説明したが、実施の形態２〜４の輝度・色差信号変換部１１９を明度・色差信号変換部１５０１に、輝度・色差信号用ラインメモリ１２０を明度・色差信号用ラインメモリ１５０２に、輝度・色差信号用送信機１２２を明度・色差信号用送信機１５０３に変形した形態であっても良い。
【０１９０】
【発明の効果】
以上のように本発明は、互いに分光透過率の異なる複数の色フィルタを受光セル単位で並置させた１つ、あるいは２つの撮像素子から被写体の分光情報を推定し、受光セル単位で取得した被写体の輝度情報で、前記被写体の分光情報から得た測色値の輝度情報を受光セル単位で置換して、あるいはスケーリングして高精細でかつ高色忠実な映像を出力できる優れた撮像装置を提供する。また、ハーフミラーとダイクロイックミラーを組み合わせて、被写体からの光を光量の損失を抑えて１つの輝度撮像素子と２つの色成分撮像素子へ入射させることができ、かつ３つのプリズムの組み合わせで省スペースを実現できる優れた色分解光学系を提供する。
【図面の簡単な説明】
【図１】本発明の実施の形態１におけるマルチバンドビデオカメラの構成を示す図
【図２】実施の形態１にかかる色分解光学系の内部構造を説明する図
【図３】（ａ） 実施の形態１にかかる、輝度撮像素子、短波長成分撮像素子、および長波長成分撮像素子を側面から見た模式的構造図
（ｂ） 実施の形態１にかかる、輝度撮像素子、短波長成分撮像素子、および長波長成分撮像素子の色フィルタの配列を説明する概念図
（ｃ） 実施の形態１にかかる、輝度撮像素子、短波長成分撮像素子、および長波長成分撮像素子の画素単位で見た色信号の配列と輝度変換部の動作と被写体分光情報推定部の動作を説明する概念図
【図４】実施の形態１にかかる色フィルタの分光透過率の一例を示す図
【図５】実施の形態１にかかる測色変換部、照明分光情報記憶部、明度信号変換部、およびセル単位明度置換部の動作を説明する図
【図６】（ａ） 実施の形態１にかかるデバイスドライブ信号用ラインメモリと、輝度・色差信号用ラインメモリの画像の第１走査ライン走査時における動作を表わした図（単位ブロックが固定された場合）
（ｂ） 実施の形態１にかかるデバイスドライブ信号用ラインメモリと、輝度・色差信号用ラインメモリ画像の第２走査ライン走査時における動作を表わした図（単位ブロックが固定された場合）
【図７】（ａ） 実施の形態１にかかるデバイスドライブ信号用ラインメモリと、輝度・色差信号用ラインメモリの画像の第１走査ライン走査時における動作を表わした図（単位ブロックが画像走査に対応して移動する場合）
（ｂ） 実施の形態１にかかるデバイスドライブ信号用ラインメモリと、輝度・色差信号用ラインメモリ画像の第２走査ライン走査時における動作を表わした図（単位ブロックが画像走査に対応して移動する場合）
【図８】本発明の実施の形態２におけるマルチバンドビデオカメラの構成を示す図
【図９】実施の形態２にかかるセル単位測色値スケーリング部の動作を説明する図
【図１０】本発明の実施の形態３におけるマルチバンドビデオカメラの構成を示す図
【図１１】本発明の実施の形態４におけるマルチバンドビデオカメラの構成を示す図
【図１２】実施の形態４にかかる色分解光学系の内部構成を示す図
【図１３】（ａ） 実施の形態４にかかる色成分撮像素子の色フィルタ配列を説明する図（ｂ） 実施の形態４にかかる画素単位の色信号の配列と被写体分光情報推定部の動作を示す図
【図１４】実施の形態４にかかる９種類の色フィルタｆ₁からｆ₉の分光透過率の一例を示す図
【図１５】本発明の実施の形態５におけるマルチバンドビデオカメラの構成を示す図
【符号の説明】
１０１、１１０２ 撮像レンズ
１０２、１１０１ 色分解光学系
１０３、１１０３ 輝度撮像素子
１０４、８０３、１１０７ 輝度信号生成部
１０５ 明度信号変換部
１０６ 短波長成分撮像素子
１０７ 長波長成分撮像素子
１０８ 短波長成分色信号処理部
１０９ 長波長成分色信号処理部
１１０、８０４ 被写体分光情報推定部
１１１ 分光情報出力端子
１１２、８０２ 測色値変換部
１１３、８０５ 照明分光情報記憶部
１１４ セル単位明度信号置換部
１１５ 測色値出力端子
１１６、８０６ 原色変換部
１１７ ガンマ補正部
１１８ デバイスドライブ信号用ラインメモリ
１１９ 輝度・色差信号変換部
１２０ 輝度・色差信号用ラインメモリ
１２１ デバイスドライブ信号用送信機
１２２ 輝度・色差信号用送信機
２０１、１２０３ 撮像レンズからの入射光
２０２ 第１光学プリズム
２０３、１２０１ ハーフミラー
２０４ 第１反射光
２０５ 第１透過光
２０６ 第１光学プリズムの面
２０７ 第１光学プリズムの面
２０８ エアギャップ
２０９ 第２光学プリズム
２１０ 長波長成分反射ダイクロイックミラー
２１１ 第２反射光
２１２ 第２透過光
２１３ 第２光学プリズムの面
２１４ 第２光学プリズムの面
２１５、１２０２ 赤外吸収フィルタ
２１６ 第３光学プリズム
３０１ 基板
３０２ 受光セル
３０３ 色フィルタ
６０１、６０２ ラインメモリ
６０３、６０４、７０１ セル
８０１ セル単位測色値スケーリング部
１１０４ 色成分撮像素子
１１０５ 色成分信号処理部
１１０６ 被写体分光情報推定部
１２０４ 透過光
１２０５ 反射光
１５０１ 明度・色差信号変換部[0001]
BACKGROUND OF THE INVENTION
The present invention can accurately estimate spectral information of a subject. Regarding imaging devices Technology.
[0002]
[Prior art]
Due to advances in digitization and integration technology, imaging devices such as video cameras, digital cameras, still cameras, and scanners that can acquire high-definition images are actively developed. From the viewpoint of color management, the imaging device must accurately capture the colorimetric value or spectral information of the subject, and improve the estimation accuracy for estimating the colorimetric value or spectral information of the subject from the output signal of the image sensor. Is the key. In order to smoothly exchange color information, in recent digital cameras, sRGB signals are output as standard signals.
[0003]
However, to accurately obtain the colorimetric value of the subject by linearly converting the output signal of the image sensor having three color filters of R, G, and B, the spectral transmittance distribution of the color filter is a linear combination of color matching functions. It is necessary to satisfy the so-called router condition that can be expressed by When the router condition cannot be satisfied, it is necessary to perform nonlinear conversion on the output signal of the image sensor. In many cases, accurate colorimetric estimation is difficult, and conversion errors into sRGB signals are likely to occur. Even if the colorimetric estimation can be accurately realized, there remains a problem of condition color matching, and it is desired to accurately estimate the spectral reflectance of the subject.
[0004]
However, when the spectral reflectance of the subject is estimated discretely every 10 nm in the visible range from 400 nm to 700 nm, the spectral reflectance vector is a 31-dimensional vector. Therefore, it can be understood from the difference between the number of dimensions of the spectral reflectance vector (that is, 31) and the channel of the imaging device (that is, 3) that spectral reflectance estimation with a three-band camera is not easy.
[0005]
As described above, since it is difficult to accurately estimate color information in a three-band imaging device using three color filters of R, G, and B, a multiband imaging device with an increased number of bands is an effective means. .
[0006]
Sugiura et al., For example, uses a spectral image input system (Color Forum JAPAN'99, P65-P72) to shoot multiband images in a time-sharing manner using five bandpass filters and one image sensor. The technology of a multiband camera is disclosed. If the number of bands is increased in this way, the accuracy of spectral estimation is improved, but the child method is a time-division photographing method, so that there is a problem that the number of photographing increases.
[0007]
Therefore, in recent years, research related to the trade-off between the number of bands and color estimation accuracy (for example, Murakami et al. “Development of a color image system capable of accurate color reproduction (Color Forum JAPAN'99, P5-P8)”). Research has been actively conducted, and about 5 to 10 bands have been reported as appropriate.
[0008]
However, in the time division method, the photographing time is increased by the number of bands, and it is difficult to photograph a moving subject. Japanese Laid-Open Patent Publication No. 4-329322 discloses a technique for simultaneously capturing multiband images by providing an image sensor for each bandpass filter.
[0009]
[Problems to be solved by the invention]
However, the above-described conventional simultaneous shooting type multiband imaging device has the following problems.
[0010]
In recent research reports to academic societies, as described above, at least five bands or more are required for accurate estimation of the spectral reflectance of a subject. Therefore, in the method in which an image sensor is provided for each bandpass filter, at least five image sensors are required. Furthermore, a color separation optical system that divides the light input from the imaging lens into five optical paths is required, resulting in an increase in apparatus size and weight. In addition, when the size of the color separation optical system is increased, the distance from the imaging lens to the imaging element is increased. As a result, the aperture of the imaging lens is also increased, and the cost of the imaging apparatus is increased.
[0011]
The present invention has been made in view of this point, and an object of the present invention is to simultaneously capture a multiband image having a necessary number of bands with a smaller number of image sensors than the number of bands necessary for estimating spectral information of a subject. And
[0012]
[Means for Solving the Problems]
In order to achieve this object, the present invention divides light input from an imaging lens into two optical paths by a half mirror, generates a luminance image from one light, and converts the other light into a short wavelength component and a long wavelength component. The spectral information of the subject is estimated from the light of the short wavelength component and the light of the long wavelength component, respectively, and the brightness information of the colorimetric value calculated from the estimated spectral information of the subject is converted into a brightness signal converted by the brightness signal converter. Replaced by cell unit.
[0013]
This makes it possible to simultaneously capture multiple band images with a smaller number of image sensors than the number of bands required for spectral estimation while maintaining high-resolution luminance component information with high resolution in the visual system. Movie shooting is possible.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
An imaging apparatus according to a first aspect of the present invention receives a half mirror that divides light from an imaging lens into two optical paths, and receives one light divided by the half mirror, and acquires luminance information of the subject. A luminance imaging device that generates a luminance signal from the luminance information and outputs the luminance signal, a luminance signal converter that converts the luminance signal into a luminance signal, and the other light divided by the half mirror is shortened. A dichroic mirror that divides the wavelength component into a long wavelength component, and a short wavelength component imaging that outputs the color signal corresponding to the received light by receiving light of the short wavelength component through a plurality of different color filters in different light receiving cells. A long wavelength component imaging device that receives light of the long wavelength component through a plurality of different color filters in different light receiving cells and outputs a color signal corresponding to the received light; A subject spectral information estimation unit that estimates spectral information of a subject from the color signal output from the short wavelength component imaging device and the long wavelength component imaging device, and the brightness signal conversion of the brightness information of the colorimetric value calculated from the spectral information A unit-by-cell brightness signal replacement unit that replaces the brightness signal converted by the unit in units of the light-receiving cells.
[0015]
In this way, the lightness component information with high resolving power of the visual system is acquired with high precision by the luminance image sensor, and at the same time, only the lightness component of the colorimetric value acquired from the short wavelength component image sensor and the long wavelength component image sensor Is replaced with the light receiving cell unit of the image sensor with the lightness component information from the luminance image sensor, thereby reducing the number of color filters provided in the light receiving cells of the short wavelength component image sensor and the long wavelength component image sensor to 2 Multi-band images can be taken simultaneously with two imaging elements, and still images and moving images can be taken of fast-moving subjects.
[0016]
An imaging apparatus according to a second aspect of the present invention receives a half mirror that divides light from an imaging lens into two optical paths, and receives one light divided by the half mirror to obtain luminance information of the subject. A luminance imaging device that generates a luminance signal from the luminance information and outputs the luminance signal, a luminance signal converter that converts the luminance signal into a luminance signal, and the other light divided by the half mirror is shortened. A dichroic mirror that divides the wavelength component into a long wavelength component, and a short wavelength component imaging that outputs the color signal corresponding to the received light by receiving light of the short wavelength component through a plurality of different color filters in different light receiving cells. A long wavelength component imaging device that receives light of the long wavelength component through a plurality of different color filters in different light receiving cells and outputs a color signal corresponding to the received light; A subject spectral information estimation unit for estimating spectral information of a subject from the color signal output from the short wavelength component imaging device and the long wavelength component imaging device, and a colorimetric value calculated from the spectral information by the luminance signal as the light receiving cell. A cell unit colorimetric value scaling unit that performs scaling in units is employed.
[0017]
In this way, luminance component information with high resolving power of the visual system is acquired with high definition by the luminance imaging device, and colorimetric values acquired from the short wavelength component imaging device and the long wavelength component imaging device are simultaneously acquired by the luminance imaging. By scaling the luminance component information from the element to the light receiving cell unit of the image sensor, the number of color filters provided in the light receiving cell of the short wavelength component image sensor and the long wavelength component image sensor is less than two types of image sensors. Multiband images can be taken simultaneously, and still images and moving images can be taken of fast-moving subjects.
[0018]
According to a third aspect of the present invention, in the imaging device according to the first aspect or the second aspect, the arrangement of the color filters in the entire short wavelength component imaging device is a repetition of a unit block composed of a plurality of adjacent cells. When the color filters of the short wavelength component image sensor have different spectral transmittance distributions in the unit block, and the spectral transmittance distributions of all the color filters in the unit block are combined, It covers the wavelength band of the light of the short wavelength component.
[0019]
In this way, light of short wavelength components divided by the dichroic mirror is received without waste, and color component information with low resolving power of the visual system is acquired for each unit block, whereby a plurality of multiband images are obtained with one image sensor. Has the effect of photographing.
[0020]
According to a fourth aspect of the present invention, in the imaging device according to the first aspect or the second aspect, the arrangement of the color filters in the entire long wavelength component imaging device is a repetition of a unit block composed of a plurality of adjacent cells. When the color filters of the long wavelength component image sensor have different spectral transmittance distributions in the unit block, and the spectral transmittance distributions of all the color filters in the unit block are combined, Covers the wavelength band of the light of the long wavelength component.
[0021]
In this way, the light of the long wavelength component divided by the dichroic mirror is received without waste, and the color component information with low resolution of the visual system is acquired for each unit block, so that a plurality of multiband images can be obtained with one image sensor. Has the effect of photographing.
[0022]
An imaging apparatus according to a fifth aspect of the present invention obtains luminance information of the subject by receiving a half mirror that divides light from an imaging lens into two optical paths and one light that is divided by the half mirror. A luminance imaging device that generates a luminance signal from the luminance information and outputs the luminance signal, a luminance signal converter that converts the luminance signal into a luminance signal, and the other light divided by the half mirror is different A color imaging element that receives light from a plurality of different light receiving cells through a plurality of color filters and outputs a color signal corresponding to the received light, a subject spectral information estimation unit that estimates spectral information of the subject from the color signal, and the spectral A cell unit lightness signal replacement unit that replaces only the lightness information among the colorimetric values calculated from the information with the lightness information converted by the lightness signal conversion unit for each light receiving cell. .
[0023]
In this way, the lightness component information with high resolving power of the visual system is acquired with high precision by the luminance image sensor, and at the same time, only the lightness component of the colorimetric value acquired from the short wavelength component image sensor and the long wavelength component image sensor Is replaced with the light-receiving cell unit of the image sensor by the lightness component information from the luminance image sensor, thereby reducing the number of color filters provided in the light-receiving cells of the short wavelength component image sensor and the long wavelength component image sensor to 1 Multi-band images can be taken simultaneously with two imaging elements, and still images and moving images can be taken of fast-moving subjects.
[0024]
An imaging apparatus according to a sixth aspect of the present invention receives a half mirror that divides light from an imaging lens into two optical paths, and receives one light divided by the half mirror to obtain luminance information of the subject. A luminance imaging device that generates a luminance signal from the luminance information and outputs the luminance signal, a luminance signal converter that converts the luminance signal into a luminance signal, and the other light divided by the half mirror is different A color imaging element that receives light from a plurality of different light receiving cells through a plurality of color filters and outputs a color signal corresponding to the received light, a subject spectral information estimation unit that estimates spectral information of the subject from the color signal, and the spectral A cell unit colorimetric value scaling unit that scales a colorimetric value calculated from information in units of the light receiving cell by the luminance signal is adopted.
[0025]
In this way, luminance component information with high resolving power of the visual system is acquired with high definition by the luminance imaging device, and colorimetric values acquired from the short wavelength component imaging device and the long wavelength component imaging device are simultaneously acquired by the luminance imaging. By scaling the luminance component information from the element to the light receiving cell unit of the image pickup element, the number of color filters provided in the light receiving cell of the short wavelength component image pickup element and the long wavelength component image pickup element can be reduced by one image pickup element. Multiband images can be taken simultaneously, and still images and moving images can be taken of fast-moving subjects.
[0026]
According to a seventh aspect of the present invention, in the imaging device according to the fifth aspect or the sixth aspect, the color imaging element receives light through a color filter for each light receiving cell of the imaging element, and the color filter is adjacent to the color imaging element. Spectral transmittance that covers the wavelength band incident from the imaging lens by combining a plurality of light receiving cells as unit blocks, having different spectral transmittance distributions in the unit block, and combining all color filters in the unit block The arrangement of the color filters having the distribution and the entire color imaging device is a repeating pattern of the unit blocks.
[0027]
In this way, by receiving light divided by the half mirror without waste and acquiring color component information with low resolution of the visual system in units of unit blocks, it is possible to capture a plurality of multiband images with one image sensor.
[0028]
According to an eighth aspect of the present invention, in the imaging device according to any one of the first to seventh aspects, the unit block includes two vertical cells and two horizontal cells, and the subject spectral information estimation unit includes: The spectral information of the subject is estimated for each unit block.
[0029]
Thereby, it has the effect | action which can image | photograph four multiband images for every unit block simultaneously with one image pick-up element.
[0030]
According to a ninth aspect of the present invention, in the imaging device according to any one of the first to seventh aspects, the vertical position of the unit block is a scanning line in which the first line of the unit block is an image scan line. Is determined to match.
[0031]
Thus, the output signal of the image pickup apparatus can be output in a stream format without being temporarily held in the line memory, and the spectral information of the subject can be accurately estimated for each scanning line.
[0032]
According to a tenth aspect of the present invention, in the imaging device according to any one of the first to seventh aspects, the unit block is composed of vertical n cells, and (n−1) in the unit block An external output signal corresponding to a line is stored in a line memory, and the external output signals after the second line in the unit block are output from the line memory.
[0033]
As a result, among the multi-band images generated simultaneously for n lines in the light receiving cell unit, the first line is output without going through the line memory, and the (n−1) lines after the second line are synchronized with the image scanning. The output from the line memory can be used for various scanning methods.
[0034]
According to an eleventh aspect of the present invention, in the imaging device according to any one of the first aspect, the second aspect, the fifth aspect, and the sixth aspect, an illumination spectral information storage unit that stores spectral information of illumination; A colorimetric value conversion unit that calculates a colorimetric value of the subject using the illumination spectral information held in the illumination spectral information storage unit, and the cell unit lightness signal replacement unit or the cell unit colorimetry The value scaling unit obtains the spectral information of the subject estimated by the subject spectral information estimation unit and the colorimetric value information from the colorimetric value conversion unit.
[0035]
Thus, the colorimetric value having the brightness replaced in the light receiving cell unit of the image sensor or the colorimetric value to be scaled can be calculated from the spectral information of the subject and the spectral information of the illumination.
[0036]
According to a twelfth aspect of the present invention, in the imaging apparatus according to any one of the first aspect, the second aspect, the fifth aspect, and the sixth aspect, the cell unit lightness signal replacement unit or the cell unit colorimetric value. A primary color conversion unit that converts a colorimetric value calculated by the scaling unit for each light receiving cell into a luminance linear drive level of a display device; a gamma correction unit that corrects gamma characteristics of the display device from an output of the primary color conversion unit; A luminance / color difference signal conversion unit for calculating a luminance / color difference signal from the output of the gamma correction unit is employed.
[0037]
Accordingly, the colorimetric value in which the lightness is replaced in units of light receiving cells of the image sensor or the scaled colorimetric value can be converted into a luminance / color difference signal including gamma correction processing of the display device.
[0038]
According to a thirteenth aspect of the present invention, in the imaging apparatus according to any one of the first, second, fifth, or sixth aspects, the cell unit lightness signal replacement unit or the cell unit colorimetric value. A primary color conversion unit that converts a colorimetric value calculated by the scaling unit for each light receiving cell into a luminance linear drive level of a display device; a luminance / color difference signal conversion unit that calculates a luminance / color difference signal from an output of the primary color conversion unit; The structure which comprised these is taken.
[0039]
Thus, the colorimetric value in which the lightness is replaced in units of light receiving cells of the image sensor or the scaled colorimetric value can be converted into the luminance / color difference signal while maintaining the luminance linearity.
[0040]
According to a fourteenth aspect of the present invention, in the imaging device according to any one of the first, second, fifth, or sixth aspects, the cell unit lightness signal replacement unit or the cell unit colorimetric value scaling is provided. The unit includes a lightness / color difference signal conversion unit that converts a colorimetric value calculated for each light receiving cell into a lightness component and a color difference component.
[0041]
Thus, the colorimetric value in which the lightness is replaced in the light receiving cell unit of the image sensor or the scaled colorimetric value can be converted into the lightness / color difference signal while maintaining the lightness linearity.
[0042]
According to a fifteenth aspect of the present invention, in the imaging apparatus according to the twelfth aspect or the thirteenth aspect, the luminance / color-difference signal converter is a device drive signal or luminance linear device drive that cancels gamma characteristics of a video display device. A luminance signal is generated by a linear sum of signals, and all the elements of the device drive signal or the constituent elements of the luminance linear device drive signal are excluded except for the element that contributes most to the luminance signal generation in the linear sum. The difference value obtained by subtracting the luminance signal from each is used as a color difference signal, and the luminance signal and the color difference signal are output.
[0043]
This ensures linearity of the luminance of the device drive signal and emission color without providing a special processing unit in the display device, and enables signal transmission with a luminance / color difference signal with a smaller band than the device drive signal. Have the effect of
[0044]
According to a sixteenth aspect of the present invention, in the imaging apparatus according to the fourteenth aspect, the lightness / color difference signal conversion unit is a linear sum of a device drive signal or a luminance linear device drive signal that cancels a gamma characteristic of a video display device. A luminance signal is generated, and the luminance signal is derived from each of all the elements of the device drive signal or the luminance linear device drive signal except for the element having the largest contribution rate to the luminance signal generation in the linear sum. The difference value obtained by subtracting is used as a color difference signal, the luminance signal is converted into a brightness signal by an exponential function, and the brightness signal and the color difference signal are output.
[0045]
This ensures the linearity of the brightness of the device drive signal and emission color without providing a special processing unit in the video display device, and enables signal transmission with a lightness / color difference signal with a smaller band than the device drive signal. Has the effect of
[0046]
According to a seventeenth aspect of the present invention, in the imaging apparatus according to the fifteenth aspect or the sixteenth aspect, the device drive signal that cancels the gamma characteristic of the video display device is composed of three bands of R, G, and B, or When the luminance linear device drive signal is composed of three bands of R, G, and B, the R band contribution ratio is 0.30, the G band contribution ratio is 0.59, and the B band contribution ratio is 0.11. The luminance signal is calculated as the sum.
[0047]
Thereby, it has the effect | action which enables exact color reproduction with the video display device which has a decoder of an EIA-RS 170A system.
[0048]
According to an eighteenth aspect of the present invention, in the imaging apparatus according to the fifteenth aspect or the sixteenth aspect, the device drive signal that cancels the gamma characteristic of the video display device is composed of three bands of R, G, and B, or When the luminance linear device drive signal is composed of three bands of R, G, and B, the R band contribution ratio is 0.299, the G band contribution ratio is 0.587, and the B band contribution ratio is 0.114. The luminance signal is calculated as the sum.
[0049]
Thus, the video display device having the SMPTE 170M decoder has an effect of enabling accurate color reproduction.
[0050]
According to a nineteenth aspect of the present invention, in the imaging apparatus according to the fifteenth aspect or the sixteenth aspect, the device drive signal that cancels the gamma characteristic of the video display device is composed of three bands of R, G, and B, or When the luminance linear device drive signal is composed of three bands of R, G, and B, the R band contribution ratio is 0.2126, the G band contribution ratio is 0.7152, and the B band contribution ratio is 0.0722. The luminance signal is calculated as the sum.
[0051]
As a result, ITU-R Rec. BT. The video display device having a 709-3 decoder has an effect of enabling accurate color reproduction.
[0052]
A color separation optical system according to a twentieth aspect of the present invention includes a first optical prism having a half mirror that divides incident light into two optical paths, and one of the lights divided by the first optical prism. A second optical prism including a dichroic mirror that reflects only a short wavelength component; a third optical prism that transmits a long wavelength component transmitted by the second optical prism; the first optical prism; and the second optical prism. An air gap is provided between the optical prism and the optical prism.
[0053]
With this configuration, the color separation optical system that divides the light from the subject into the luminance component and the two color components of the short wavelength and the long wavelength can be reduced in size by the volume of the three optical prisms.
[0054]
According to a twenty-first aspect of the present invention, in the color separation optical system according to the twentieth aspect, the third optical prism includes an infrared absorption filter on a boundary surface where the long wavelength component is output from the prism to the outside of the prism. The structure to comprise is taken.
[0055]
With this configuration, the noise from the image sensor having sensitivity to infrared light can be suppressed with a simple configuration.
[0056]
A color separation optical system according to a twenty-second aspect of the present invention includes a first optical prism having a half mirror that divides incident light into two optical paths, and one of the lights divided by the first optical prism. A second optical prism including a dichroic mirror that reflects only a long wavelength component; a third optical prism that transmits a short wavelength component transmitted by the second optical prism; the first optical prism; and the second optical prism. An air gap is provided between the optical prisms.
[0057]
With this configuration, the color separation optical system that divides the light from the subject into the luminance component and the color component can be reduced in size by the volume of the two optical prisms.
[0058]
According to a twenty-third aspect of the present invention, in the color separation optical system according to the twenty-second aspect, the second optical prism includes an infrared ray on a boundary surface where the reflected long wavelength component is output from the inside of the prism to the outside of the prism. The structure which comprises an absorption filter is taken.
[0059]
With this configuration, the noise from the image sensor having sensitivity to infrared light can be suppressed with a simple configuration.
[0060]
(Embodiment 1)
Hereinafter, a multiband video camera which is an imaging apparatus according to the first embodiment of the present invention will be described. First, a system of a multiband video camera that simultaneously captures a multiband image with the three image sensors in Embodiment 1 will be described with reference to FIG. FIG. 1 is a system configuration diagram of a multiband video camera that simultaneously captures a multiband image with three image sensors in Embodiment 1 of the present invention.
[0061]
Light from the subject enters the color separation optical system 102 through the imaging lens 101. Then, the color separation optical system 102 divides the incident light into three optical paths: a first optical path, a second optical path, and a third optical path.
[0062]
The first light path is supplied with the same light as the light that has passed through the imaging lens 101 as spectral characteristics. A luminance image sensor 103 is disposed on the first optical path, and light in the first optical path is incident on the luminance image sensor 103. The luminance imaging element 103 outputs a signal corresponding to the light incident on each light receiving cell to the lightness signal conversion unit 105. The signal value output for each light receiving cell of the luminance imaging element 103 is adjusted as a luminance signal by the luminance signal generation unit 104 and output to the lightness signal conversion unit 105. The lightness signal conversion unit 105 converts the input luminance signal into a lightness signal using an exponential function and outputs the lightness signal.
[0063]
A short wavelength component of light that has passed through the imaging lens 101 is supplied to the second optical path as spectral characteristics. A short wavelength component image sensor 106 is disposed on the second optical path, and light in the second optical path is incident on the short wavelength component image sensor 106. A long wavelength component of light that has passed through the imaging lens 101 is supplied to the third optical path as spectral characteristics. A long wavelength component image sensor 107 is disposed on the third optical path, and light in the third optical path is incident on the long wavelength component image sensor 107. However, the light in the second optical path and the light in the third optical path are spectrally divided based on the light that has passed through the imaging lens 101 in the color separation optical system 102, and the wavelength bands of these two lights Is equal to the wavelength band of the light that has passed through the imaging lens 101.
[0064]
The short wavelength component image sensor 106 receives light through a plurality of color filters having different spectral transmittance distributions close to the light receiving cell. Then, the short wavelength component imaging device 106 outputs a color signal corresponding to the incident light for each light receiving cell to the short wavelength component color signal processing unit 108. The short wavelength component color signal processing unit 108 simultaneously generates multiband images corresponding to the number of types of color filters from the input color signal values. Similarly, the long wavelength component imaging device 107 receives light through a plurality of color filters having different spectral transmittance distributions close to the light receiving cell, and the long wavelength component color signal processing unit 109 has the same number of types of color filters. Multi-band images are generated simultaneously.
[0065]
Both the multiband images generated by the short wavelength component color signal processing unit 108 and the long wavelength component color signal processing unit 109 are supplied to the subject spectral information estimation unit 110, and the spectral information of the subject is estimated. The spectral information of the subject is an estimation of an emission spectrum when the subject is a self-luminous body, and is a spectral reflectance when the subject is a reflective object that reflects illumination light. Further, the spectral information of the estimation result by the subject spectral information estimation unit 110 can be output to the outside of the camera via the spectral information output terminal 111. The spectral information of the subject estimated by the subject spectral information estimation unit 110 is provided to the colorimetric value conversion unit 112.
[0066]
The colorimetric value conversion unit 112 converts the input spectral information into lightness components such as CIELAB values (ie, LIEL values) via the CIEXYZ tristimulus values. ^* ) And color components (ie a ^* , B ^* ) Is converted into the colorimetric values separated. However, the illumination spectral information necessary for calculating the colorimetric value is stored in advance in the illumination spectral information storage unit 113 and is provided from the illumination spectral information storage unit 113 to the colorimetric value conversion unit 112. The colorimetric value calculated by the colorimetric value conversion unit 112 is input to the cell unit lightness signal replacement unit 114.
[0067]
The cell unit lightness signal replacement unit 114 replaces only the lightness component of the colorimetric values output from the colorimetric value conversion unit 112 with the lightness signal generated in lightness cell units in the lightness signal conversion unit 105.
[0068]
Further, when it is desired to take out color information of the captured subject as a colorimetric value, it can be output to the outside of the camera via the colorimetric value output terminal 115. The colorimetric value of the light receiving cell unit output from the cell unit lightness signal replacement unit 114 is converted into a primary color signal of the video display device by the primary color conversion unit 116. The luminance linear device drive signal output from the primary color conversion unit 116 is subjected to a reverse gamma characteristic that cancels the gamma characteristic of the video display device in the gamma correction unit 117, and the device drive signal line memory 118 is used as the device drive signal. And supplied to the luminance / color difference signal converter 119. The luminance / color difference signal conversion unit 119 converts the device drive signal into a luminance signal and a color difference signal, and outputs them to the luminance / color difference signal line memory 120.
[0069]
Two types of line memories, a device drive signal line memory 118 and a luminance / color difference signal line memory 120, are provided to cope with the difference in scanning method, and include a short wavelength component imaging element 106 and a long wavelength component imaging. The operation is determined according to the arrangement of the color filters of the element 107. Therefore, a detailed description will be given after the description of the color filter of the image sensor. Furthermore, the device drive signal transmitter 121 and the luminance / color difference signal transmitter 122 are provided to support various communication protocols, and the captured video signal of the multiband video camera is determined to a receiving device such as a display. Output according to the specified protocol.
[0070]
Next, the color separation optical system 102, the luminance imaging device 103, the short wavelength component imaging device 106, the long wavelength component imaging device 107, the subject spectral information estimation unit 110, the colorimetric value conversion unit 112, the cell unit lightness signal replacement unit 114, The primary color conversion unit 116, gamma correction unit 117, luminance / color difference signal conversion unit 119, device drive signal line memory 118, and luminance / color difference signal signal line memory 120 will be described in detail step by step.
[0071]
First, the color separation optical system 102 will be described in detail with reference to FIG. FIG. 2 is a diagram illustrating the internal structure of the color separation optical system according to the first embodiment.
[0072]
The color separation optical system 102 separates light from the subject into three components, a luminance component, a short wavelength component, and a super wavelength component, using three optical prisms.
[0073]
The color separation optical system 102 includes a first optical prism 202 that is a triangular prism, a second optical prism 209 that is a triangular prism, and a third optical prism 216 that is a trapezoidal prism.
[0074]
The first optical prism 202 is disposed perpendicular to the incident light 201 from the imaging lens 101, and is a first surface 206 that is an incident surface on which the incident light 201 is incident, and the long wavelength component imaging element 107 side of the first surface 206. Are connected to the luminance imaging device 103 side of the first surface 206 and the half mirror 203 which is a semi-transmissive surface (second surface) of the incident light 201 whose normal line is inclined at a predetermined angle toward the luminance imaging device 103 side. The third surface 207 is a transmission surface whose surface normal is perpendicular to the direction of the luminance image sensor 103.
[0075]
The half mirror 203 divides the incident light 201 into two lights, a first reflected light 204 that is reflected light and a first transmitted light 205 that is transmitted light. The half mirror 203 has no wavelength selectivity, and the two divided lights, the first reflected light 204 and the first transmitted light 205 have the same spectral distribution.
[0076]
Since the normal line of the half mirror 203 is inclined toward the luminance imaging element 103 side, the first reflected light 204 is inclined toward the luminance imaging element 103 side with respect to the incident light 201. The first reflected light 204 is incident on the first surface 206 of the first optical prism 202 at a critical angle or more, and all the first reflected light 204 is reflected by the first surface 206, and the direction of the third surface 207 is reached. Proceed to Then, the first reflected light 204 passes through the third surface 207 and enters the luminance imaging element 103.
[0077]
On the other hand, the first transmitted light 205 is incident on the first optical prism 202 and the second optical prism 209 disposed via the air gap 208.
[0078]
The second optical prism 209 is a transmission surface on which the first transmitted light 205 is incident, and a first surface 213 disposed in parallel with the half mirror 203 of the first optical prism 202 via the air gap 208, and a first surface. A long-wavelength component reflecting dichroic that is a semi-transmissive surface (second surface) of the first transmitted light 205 that is connected to the luminance imaging device 103 side of the surface 213 and whose normal to the surface is inclined at a predetermined angle toward the long-wavelength component imaging device 107 side. The mirror 210 and a third surface 214 that is connected to the long wavelength component imaging device 107 side of the first surface 213 and whose surface normal is perpendicular to the long wavelength component imaging device 107 side.
[0079]
The long wavelength component reflecting dichroic mirror 210 divides the first transmitted light 205 into two light components, a short wavelength component and a long wavelength component, and reflects the second reflected light 211, which is the light of the long wavelength component, to reduce the short wavelength component. The second transmitted light 212 that is the light of the wavelength component is transmitted.
[0080]
The second reflected light 211 is incident on the first surface 213 of the second optical prism 209 at a critical angle or more. Since there is an air gap 208 between the first surface 213 and the first optical prism 202, all the light of the second reflected light 211 is reflected by the first surface 213, and the long wavelength passes through the third surface 214. The light enters the component image sensor 107. In addition, an infrared absorption filter 215 is deposited on the second surface 214 to suppress noise of the image sensor having sensitivity in the infrared region.
[0081]
The second transmitted light 212 is incident on the third optical prism 216. The third optical prism 216 includes a first surface 217 that is a transmission surface that is in contact with the long wavelength component reflecting dichroic mirror 210 of the second optical prism 209, and a short wavelength component imaging device 106 that is spaced apart from the first surface 217 by a predetermined distance. It is comprised from the 2nd surface 218 arrange | positioned horizontally, the 3rd surface 219 and the 4th surface 220 which contact the 1st surface 217 perpendicularly | vertically with the 2nd surface 218.
[0082]
The wavelength at the boundary between reflection and transmission of the long-wavelength component reflection dichroic mirror 210, so-called cutoff wavelength, is used only for the transmission region of the color filter of the light-receiving cell of the long-wavelength component image sensor 107 in order to minimize light loss. Is set to reflect. With the above configuration, the light from the subject can be decomposed into two color components of a luminance component, a short wavelength, and a long wavelength using three optical prisms, and the size can be reduced to the volume of the three optical prisms.
[0083]
The second transmitted light 212 enters from the first surface of the third optical prism 216, forms an image by the third optical prism 216, passes through the second surface 217, and enters the short wavelength component imaging device 106.
[0084]
In addition, the ratio of the light quantity of the 1st reflected light 204 and the 1st transmitted light 205 divided | segmented into two by the half mirror 203 is three image sensors, the luminance image sensor 103, the short wavelength component image sensor 106, and long wavelength component imaging. It is desirable to optimize according to the sensitivity characteristic of the element 107. The long wavelength component reflecting dichroic mirror 210 may be a long wavelength component transmitting dichroic mirror. However, in this case, the positions of the short wavelength component imaging device 106 and the long wavelength component imaging device 107 are switched, and at the same time, an infrared absorption filter is also installed in the third optical prism.
[0085]
Secondly, the luminance imaging device 103, the short wavelength component imaging device 106, and the long wavelength component imaging device 107 will be described in detail with reference to FIG. FIG. 3 is a conceptual diagram illustrating the structures of the light-receiving cell and the color filter of the luminance image sensor, the short wavelength component image sensor, and the long wavelength component image sensor according to the first embodiment.
[0086]
FIG. 3A is a schematic structural view of the image sensor as viewed from the side, and is a diagram common to the luminance image sensor 103, the short wavelength component image sensor 106, and the long wavelength component image sensor 107. A plurality of light receiving cells 302 are arranged side by side on the substrate 301. A plurality of color filters 303 having different spectral transmittance distributions are closely arranged on the plurality of light receiving cells 302.
[0087]
The short wavelength component imaging device 106 and the long wavelength component imaging device 107 receive light in the light receiving cell 302 through the color filter 303. However, the luminance image sensor 103 does not have the color filter 302 and receives light without wavelength selectivity.
[0088]
FIG. 3B is a conceptual diagram illustrating an arrangement of color filters of the luminance image sensor, the short wavelength component image sensor, and the long wavelength component image sensor.
[0089]
Since the luminance image sensor 103 does not have a color filter, it is temporarily indicated as L. The short wavelength component image sensor 106 is f ₁ To f _Four Are provided in block units of 2 vertical cells and 2 horizontal cells. Similarly, the long wavelength component image sensor 107 is f _Five To f ₈ Are provided in block units of 2 vertical cells and 2 horizontal cells.
[0090]
Eight kinds of color filters f combining the short wavelength component image sensor 106 and the long wavelength component image sensor 107 ₁ To f ₈ Have different spectral transmittance distributions, for example, as shown in FIG. 4, eight have a relationship covering the visible region (from 380 nm to 780 nm in FIG. 4). That is, light in the entire visible range is received by the eight color filters.
[0091]
As described above, by sharing the light in the entire visible range with the eight color filters and receiving the light, each band is narrower and the number of bands is increased as compared with the conventional three-band camera. For this reason, when performing spectral estimation of a subject, an 8-band camera has a higher degree of freedom than a 3-band camera, and has the possibility of improving spectral estimation accuracy structurally.
[0092]
The subject spectral information estimation unit 110 includes a color filter f ₁ To f ₈ The spectral information of the subject is estimated based on these eight signals. Accordingly, the subject spectral information estimation unit 110 estimates and calculates the spectral information in units of blocks of 2 vertical cells and 2 horizontal cells.
[0093]
FIG. 3C illustrates the arrangement of the color signals, the operation of the luminance conversion unit, and the subject spectral information estimation in the pixel units of the luminance imaging device, the short wavelength component imaging device, and the long wavelength component imaging device according to the first embodiment. It is a conceptual diagram explaining operation | movement of a part.
[0094]
The luminance signal generator 104 generates a luminance signal Y for each light receiving cell. _ij (I = 1, 2,..., M, j = 1, 2,..., N) are generated. On the other hand, the subject spectral information estimation unit 110 performs spectral information signal R for each block unit of two vertical cells and two horizontal cells. _kl ((K = 1, 2,..., M / 2, l = 1, 2,..., N / 2). Therefore, the spectral information signal that is a color component is ½ of the luminance signal. The horizontal resolution is 1/2.
[0095]
By the way, according to Sakata et al., “Spatial frequency characteristics of chromaticity in the visual system (color difference discrimination threshold), Television Vol. 31, No. 1 (1997)”, the visual system is highly sensitive to luminance modulation and vice versa. The sensitivity to color modulation is low. The discrimination ability using a spatial sine wave of opposite color pairs (constant luminance) has a sensitivity peak at 0.3 cycles / deg. On the other hand, the discrimination ability using a spatial sine wave (constant chromaticity) created only with an achromatic color component has a peak at 3 cycles / deg.
[0096]
Based on the above results, it is important that the color information of the subject captured by the camera captures the luminance component with high definition in view of the spatial resolution of the visual system. In other words, in order to give the camera captured image the same spatial resolution for the visual system, the tint component may have a sampling interval less than half of the luminance component.
[0097]
The present invention pays attention to the difference in spatial discrimination ability between the luminance component and the color component of the visual system as described above, and is actively used. In other words, by widening the sampling interval of the color component, it is possible to simultaneously capture multiband images and to have the effect of not reducing the spectral estimation accuracy.
[0098]
In FIG. 3, two vertical cells and two horizontal cells are used as unit blocks. However, the number of light receiving cells forming the unit block is arbitrary, and the present invention is not limited thereto. An increase in the number of light receiving cells leads to an improvement in spectral estimation accuracy, but on the other hand leads to a decrease in resolution. For this reason, the number of light-receiving cells constituting a unit block is determined by the balance between spectral estimation accuracy and spatial resolution, and should be optimized according to the color reproduction target of each system.
[0099]
Further, the spectral transmittances of the eight color filters shown in FIG. 4 have the same shape and different peak wavelengths at equal intervals, but the present invention refers to the short wavelength component image sensor 106 and the long wavelength component image sensor. The combination of all 107 color filters covers the entire visible range (for example, 380 nm to 780 nm), and does not limit the spectral shape or peak wavelength. However, in order to avoid complication of signal processing, it is desirable that the color filter arrays of the short wavelength component image sensor 106 and the long wavelength component image sensor 107 are the same.
[0100]
Third, the subject spectral information estimation unit 110 will be described in detail. Here, the spectral reflectance will be described as the spectral information of the subject. Various methods for estimating the spectral reflectance of a subject from a multiband signal have been proposed. Since the present invention does not limit the spectral estimation method, any method can be applied. Therefore, here, a method based on winner estimation will be described. The output from the short wavelength component color signal processing unit 108 is the column vector V _short = [V ₁ , V ₂ , V _Three , V _Four ] ^t , The output from the long wavelength component color signal processing unit 109 is the column vector V _long = [V _Five , V ₆ , V ₇ , V ₈ ] ^t , The camera characteristics are the matrix S, and the spectral reflectance of the subject is the column vector R = [r ₁ , R ₂ , ..., r _q ] ^t Then these have the following relationship.
[0101]
[Expression 1]

However, the column vector V representing the sensor response is
[0102]
[Expression 2]

Given in. The matrix S representing the camera characteristics is
[0103]
[Equation 3]

Given in. Here, the matrix F represents the spectral transmittance of the color filter arranged in the light receiving cell, and is composed of 8 rows and q columns assuming that 8 color filters are used. For example, when 380 nm to 780 nm are taken every 10 nm, q = 41. The matrix E is a diagonal matrix representing the spectral distribution of illumination, and q components are arranged in the diagonal component.
[0104]
In the equation (1), if the dimension (8 in this case) of the sensor response V is the same as the dimension q of the wavelength, the camera characteristic matrix S is regular and the inverse matrix S ^-1 By
[0105]
[Expression 4]

From this, the spectral reflectance of the subject can be obtained.
[0106]
However, if the band from 380 nm to 780 nm is quantized every 10 nm using eight types of color filters as in the present embodiment, q = 41 and the matrix S is not regular. In such a case, the winner estimation method is used. Now, the matrix R _real , The estimated spectral reflectance is the matrix R _est If the pseudo inverse matrix corresponding to the matrix S is G, Equation (1) is
[0107]
[Equation 5]

Equation (4) is expressed as
[0108]
[Formula 6]

It is expressed as Thus the matrix R given by _real And matrix R _est What is necessary is just to obtain the estimation matrix G that minimizes the least square error ε.
[0109]
[Expression 7]

Here, t represents a transpose and <> represents an ensemble average. The estimation matrix that minimizes ε is given by the following equation from the Wiener estimation.
[0110]
[Equation 8]

Here, the matrix ρ represents a correlation matrix. Matrix R _samples And matrix V _samples Is sample data for calculating the correlation matrix ρ, and the matrix R _samples Is the spectral reflectance matrix of the sample, V _samples Is R _samples , Corresponding to the output signals of the short wavelength component color signal processing unit 108 and the long wavelength component color signal processing unit 109.
[0111]
Fourthly, the colorimetric value conversion unit 112 and the cell unit lightness signal replacement unit 114 will be described in detail with reference to FIG. FIG. 5 is a diagram for explaining operations of the colorimetric conversion unit, the illumination spectral information storage unit, the lightness signal conversion unit, and the cell unit lightness replacement unit according to the first embodiment.
[0112]
As shown in FIG. 5, the colorimetric value conversion unit 112 is supplied from the subject spectral information and illumination spectral information storage unit 113 estimated by the subject spectral information estimation unit 110 in block units of two vertical cells and two horizontal cells. CIEXYZ tristimulus values are calculated in block units from the illumination spectral information using the following equation.
[0113]
[Equation 9]

Where r _h Represents the spectral reflectance of the h-th subject. The colorimetric value conversion unit 112 converts the CIEXYZ tristimulus value into a colorimetric value further separated into a luminance component and a color component, for example, a CIELAB value using Equation (10).
[0114]
[Expression 10]

Where X _n , Y _n , Z _n Represents the reference white CIEXYZ tristimulus values. However, the luminance component is converted into a brightness signal having a proportional relationship with the brightness interval of the visual system as shown in Expression (10). In general, the luminance value given by Equation (9) does not have a linear relationship with the brightness interval of the visual system, and if the luminance value is converted by an exponential function of about 1/3 as shown in Equation (10), It is said that a linear relationship is established with the brightness interval of the system.
[0115]
On the other hand, the brightness signal conversion unit 105 uses the brightness signal L calculated by the brightness signal generation unit 104 for each light receiving cell unit using the formula (10). ^* Convert to The colorimetric value conversion unit 112 calculates colorimetric values in units of 2 vertical cells and 2 horizontal cells, whereas the lightness signal conversion unit 105 performs lightness signal L in cell units. ^* Is calculated.
[0116]
Therefore, the cell unit lightness signal replacement unit 114 includes the lightness component L of the colorimetric values output from the colorimetric value conversion unit 112. ^* Only the output from the lightness signal converter 105 is replaced.
[0117]
As described above, since the visual system has high resolution with respect to luminance modulation, the lightness component L of the CIELAB value calculated in units of blocks of 2 vertical cells and 2 horizontal cells. ^* Only the color component a ^* And b ^* The resolution is doubled in the vertical and horizontal directions.
[0118]
By the way, if the spectral distribution of illumination stored in the illumination spectral information storage unit 113 is replaced with a spectral distribution different from the illumination of the environment where the subject is photographed, the illumination conversion can be easily performed.
[0119]
For example, suppose that the reproduced image is printed on paper by a printer, the subject is illuminated with a tungsten lamp having a color temperature of about 4000K, and the reproduced image is observed with a daylight lamp of about 6500K. If it is desired to output CIEXYZ tristimulus values defined under the visual environment for photographing the subject (that is, 4000K tungsten lamp), e in equation (9) _h Substituting the spectral distribution of a 4000K tungsten lamp for. If you want to output with CIEXYZ tristimulus values defined under the visual environment (ie 6500K daylight lamp) for observing the print, _h Substituting the spectral distribution of the 6500K daylight lamp for. This is because the illumination conversion as described above is a function unique to the multiband camera, and the multiband camera can calculate the spectral reflectance of the subject. This is a feature that has colorimetric value information based on CIEXYZ tristimulus values and is greatly differentiated from a 3-band camera that does not have spectral information.
[0120]
In this way, the colorimetric value conversion unit 112 calculates the colorimetric value of the subject using the spectral information of the illumination held in the illumination spectral information storage unit 113, so that the colorimetric value is converted into the spectral information of the subject and the spectral of the illumination. It can be calculated from information.
[0121]
Fifth, the primary color conversion unit 116 will be described in detail. The primary color conversion unit 116 converts the colorimetric value into a signal depending on the video display device. The relationship between the colorimetric value and the device-dependent signal is determined by the colorimetric value of the primary color point of the display. For example, ITU-R Rec. BT. In 709-3, chromaticity values of three primary colors are defined as colorimetric parameters. That is, the R primary color is (x, y) = (0.64, 0.33), the G primary color is (x, y) = (0.30, 0.60), and the B primary color is (x, y) = ( 0.15, 0.06), and the relationship between the luminance linear device drive signals R, G, B and the CIEXYZ tristimulus values proportional to the luminance value of the display color is given below.
[0122]
[Expression 11]

Where X _R , Y _R , Z _R Represents the CIEXYZ tristimulus value of the R primary color, and X _G , Y _G , Z _G Is the C primary colors of CIEXYZ for the primary color, X _B , Y _B , Z _B Represents the CIEXYZ tristimulus values of the B primary color. The relationship between CIEXYZ tristimulus values and xy chromaticity coordinates is
[0123]
[Expression 12]

Is given by the chromaticity coordinates of the R primary color (x _R , Y _R ), Chromaticity coordinates of the G primary color (x _G , Y _G ), Chromaticity coordinates of the B primary color (x _B , Y _B ) Can be rewritten as follows.
[0124]
[Formula 13]

As described above, the primary color conversion unit 116 converts the CIEXYZ tristimulus values into luminance linear device drive signals R, G, and B according to the equation (13).
[0125]
Note that the present invention does not limit the number of primary colors of the video display device, and the three primary colors of Expression (11) and Expression (13) can be expanded to an arbitrary number.
[0126]
Sixth, the gamma correction unit 117 will be described in detail. Currently-distributed device-dependent RGB signals are subjected to a gamma correction process of a CRT display that goes through the NTSC concept. In the CRT display, as a comprehensive input / output characteristic of a display tube, a signal processing system, etc., the relationship between the device drive signal and the light emission luminance is expressed by an exponential function of 2.2. This is the so-called gamma characteristic. Therefore, a so-called gamma correction is performed so as to cancel the gamma characteristic of the CRT display by performing exponential function conversion of 1 / 2.2 on the transmission side in advance so that the relationship between the device drive signal and the emission luminance is linear. R signal, G signal, and B signal are transmitted. The gamma correction unit 117 converts the luminance linear device drive signals R, G, and B into gamma-corrected device drive signals R ′, G ′, and B ′ using Expression (14).
[0127]
[Expression 14]

Note that the present invention does not limit the number of primary colors of the video display device, and the three primary colors of Expression (14) can be expanded to an arbitrary number.
[0128]
As described above, by providing the gamma correction unit 117, the colorimetric value in which the lightness is replaced for each light receiving cell of the image sensor can be converted into a luminance / color difference signal including the gamma correction processing of the display device.
[0129]
Seventh, the luminance / color difference signal conversion unit 119 will be described in detail. The device drive signals R ′, G ′, and B ′ are converted into luminance / color difference signals in the luminance / color difference signal conversion unit 119 so as to correspond to various transmission formats. For example, ITU-R Rec. BT. In the case of complying with 709-3, the device drive signals R ′, G ′, and B ′ are converted into luminance / color difference signals by Expression (15).
[0130]
[Expression 15]

As described above, by providing the luminance / color difference signal conversion unit 119, the luminance / color difference signal can be converted into the luminance / color difference signal while maintaining the luminance linearity of the colorimetric value in which the brightness is replaced for each light receiving cell of the image sensor. Have.
[0131]
It should be noted that the present invention does not limit the method of converting the device drive signals R ′, G ′, and B ′ into luminance / color difference signals, and can be freely set according to the transmission format. .
[0132]
For example, the luminance signal is calculated by a linear sum where the contribution ratio of the R band is 0.30, the contribution ratio of the G band is 0.59, and the contribution ratio of the B band is 0.11, so that the EIA-RS 170A system is obtained. The image display device having the EIA-RS 170A decoder can be accurately reproduced.
[0133]
In addition, the luminance signal is calculated by a linear sum where the contribution rate of the R band is 0.299, the contribution rate of the G band is 0.587, and the contribution rate of the B band is 0.114, so that the SMPTE 170M decoder can be Enables accurate color reproduction with a video display device.
[0134]
Finally, a method corresponding to a difference in scanning method, a device drive signal line memory 118, and a luminance / color difference signal line memory 120 will be described in detail. In general, the video system includes an interlace system that performs interlaced scanning every other scanning line and a progressive system that performs scanning in the order of scanning lines without interlaced. In the present invention, the short wavelength component color signal processing unit 108 and the long wavelength component color signal processing unit 109 calculate colorimetric values in units of blocks in which light receiving cells are used as vertical 2 cells and horizontal 2 cells as unit blocks. Accordingly, when viewed in the scanning line direction, the colorimetric values for two lines are obtained in one operation. Therefore, in the case of the progressive method, it is necessary to hold the color measurement value data of the second line and send the held color measurement data of the second line in accordance with the scanning timing.
[0135]
The device drive signal line memory 118 in FIG. 1 holds the captured subject color information in a device drive signal format, and stores the device drive signal held in accordance with a read instruction in accordance with the scanning timing from the device drive signal transmitter 121. Output.
[0136]
Similarly, the luminance / color-difference signal line memory 120 holds the captured subject color information in the luminance / color-difference signal format, and holds the luminance information according to the read instruction in accordance with the scanning timing from the luminance / color-difference signal transmitter 122.・ Outputs color difference signals.
[0137]
In the case of the interlace method, the spectral information of the acquired subject may be output as it is without being stored in the line memory. That is, as shown in FIG. 3, the spectral reflectance of the subject is acquired by two vertical cells. Therefore, the subject spectral information estimation unit 110 outputs the same spectral reflectance regardless of whether the interlace scanning is scanning odd lines or even lines. For this reason, the colorimetric value converter 112 outputs the same colorimetric value for both odd and even lines, and there is no need to store data in the line memory.
[0138]
However, when the number of cells in the vertical direction of the unit block for estimating the spectral reflectance of the subject is 3 or more, it is necessary to retain data in both the progressive method and the interlace method. In the case of the progressive system, if the number of cells in the vertical direction of the unit block is n, (n-1) lines of line memory are required. In the case of the interlace method, a line memory corresponding to the quotient of (n-1) / 2 is required. The signal value held in the line memory is output according to the read timing instructed from the transmitter.
[0139]
Thus, when the unit block is composed of vertical n cells, the external output signal corresponding to the (n−1) line in the unit block is stored in the line memory, and the second and subsequent lines in the unit block. Is output from the line memory to the outside of the imaging device, and among the multiband images generated simultaneously for n lines in the light receiving cell unit, the first line is output without going through the line memory, and the second and subsequent lines are output. The (n-1) line can be output from the line memory in synchronization with the image scanning, and can cope with various scanning methods.
[0140]
On the other hand, when the unit block for estimating the spectral information of the subject moves for each scanning line, it is possible to cope with the progressive method and the interlace method with a minimum configuration. FIG. 6 is a diagram for explaining operations of the device drive signal line memory and the luminance / color difference signal line memory according to the first embodiment. FIG. 6 shows a case where the spectral information of a subject is estimated using vertical 2 cells and horizontal 2 cells as unit blocks, as in FIG. FIG. 6A is a diagram showing the operation of the device drive signal line memory and the luminance / color difference signal line memory according to the first embodiment during the first scan line scanning, and FIG. FIG. 4B is a diagram illustrating operations of the device drive signal line memory and the luminance / color difference signal line memory image according to the first embodiment during the second scan line scanning.
[0141]
When the imaging apparatus is scanning the first scan line of the image, as shown in FIG. 6A, the short wavelength component image sensor 106 and the long wavelength component image sensor 107 are connected to the first scan line and the second scan line of the element. The scanning line becomes active, and signals for two lines are simultaneously output to the subject spectral information estimation unit 110 to estimate the spectral information of the subject in units of two lines. Therefore, the imaging apparatus needs to hold the output signal of the second scan line until the image scan enters the second scan line, and the spectral information is converted into a colorimetric value, and then the line memory for one line. The colorimetric values of the second scanning line are stored in 601 (corresponding to the device drive signal line memory 118 and the luminance / color difference signal line memory 120 in FIG. 1). When the scanning of the image moves to the second scanning line, as shown in FIG. 6B, the line memory 602 is independent of the short wavelength component imaging device 106, the long wavelength component imaging device 107, and the subject spectral information estimation unit 110. (Substantially the same as the line memory 601), an already calculated output signal is output to the outside.
[0142]
FIG. 7 shows a case where the position of the unit block in the spectral information estimation of the subject is moved line by line in accordance with the scanning position of the image. FIG. 7A is a diagram illustrating the operation of the device drive signal line memory and the luminance / color difference signal line memory according to the first embodiment during the first scan line scanning. FIG. 6B is a diagram illustrating operations of the device drive signal line memory and the luminance / color difference signal line memory image according to the first embodiment during the second scanning line scanning.
[0143]
At the time of scanning the first scan line of the image, the first scan line and the second scan line of the short wavelength component image sensor 106 and the long wavelength component image sensor 107 become active, as in FIG. A signal is simultaneously output to the subject spectral information estimation unit 110 to estimate the subject spectral information in units of two lines. The spectral information is converted into a colorimetric value and output to the outside as it is. When the scanning of the image moves to the second scanning line, as shown in FIG. 7B, the short wavelength component imaging element 106 and the long wavelength component imaging element 107 are active in the second scanning line and the third scanning line of the element. Thus, signals for two lines are simultaneously output to the subject spectral information estimation unit 110 to estimate the spectral information of the subject in units of two lines. Subsequently, the spectral information is converted into colorimetric values and output to the outside as they are.
[0144]
As shown in FIG. 7, if the first line of the unit block on the image sensor that performs spectral estimation moves so as to coincide with the scanning line for image scanning, a line memory as shown in FIG. 6 is not necessary. Further, since the spectral information estimated in FIG. 7 moves the image sensor one line at a time, there is an advantage that the estimation accuracy is higher than that in FIG. 6 where spectral estimation is performed every two lines.
[0145]
That is, in the case of FIG. 6, two adjacent lines in the order of odd-numbered scan lines and even-numbered scan lines have the same spectral information. For example, the adjacent cells 603 and 604 in FIG. ₁₁ have.
[0146]
On the other hand, in the case of FIG. 7, the cell 701 at the same position as the cell 604 scans the first scan line of the image. ₁₁ However, when the second scanning line of the image is scanned, the spectral information R is shown in FIG. _{twenty one} To be rewritten. Spectral information R _{twenty one} Is subject information acquired from the second and third lines of the image sensor, and subject information R acquired from the first and second lines of the image sensor. ₁₁ Is different.
[0147]
As described above, the first line of the unit block on the image sensor that performs spectral estimation is moved so as to coincide with the scanning line of the image scanning, so that it is possible to perform more accurate spectral estimation than when the unit block is fixed. In FIG. 5, it is added that the color estimation accuracy is further improved by the combination with the cell unit lightness signal replacement unit 114 which has already been described in detail.
[0148]
6 and FIG. 7, the unit block for performing spectral estimation has been described by taking 2 cells in the vertical direction and 2 cells in the horizontal direction as an example. However, the present invention is not limited to the number of cells in the unit block. Note that this can be done with.
[0149]
The device drive signal transmitter 121 and the luminance / color difference signal transmitter 122 can be adapted to any transmission format, such as ITU-R and SMPTE televisions, VTRs, disk recording formats, and many other standards. The sRGB signal used in other digital cameras can be arbitrarily supported.
[0150]
As described above, according to the first embodiment, brightness component information with high resolving power of the visual system is acquired by the luminance image sensor with high definition, and at the same time, the brightness of the colorimetric values acquired from the short wavelength component image sensor and the long wavelength component image sensor. By replacing only the component with the light-receiving cell unit of the image sensor with the lightness component information from the luminance image sensor, two types of color filters provided in the light-receiving cell of the short wavelength component image sensor and the long wavelength component image sensor are reduced. Multi-band images can be taken simultaneously with the image sensor, and still images and moving images can be taken of fast-moving subjects.
[0151]
In the first embodiment, the short wavelength component imaging device 106 and the long wavelength component imaging device 107 are different from each other, and the dichroic mirror 210 divides the short wavelength side and the long wavelength when all the color filters in the unit block are combined. Since it has a unit block consisting of a light receiving cell having a spectral transmittance distribution that covers the wavelength band of the light on the side, the light of the short wavelength component and the long wavelength component divided by the dichroic mirror 210 is received without waste, and the resolution of the visual system By acquiring low color component information for each unit block, a plurality of multiband images can be captured by one image sensor.
[0152]
Furthermore, in the first embodiment, since the unit block is composed of two vertical cells and two horizontal cells, the spectral information of the subject can be estimated for each unit block of two vertical cells and two horizontal cells. As a result, there is an effect that four multiband images can be simultaneously captured for each unit block by one image sensor. Therefore, by using two image pickup devices, the short wavelength component image pickup device 106 and the long wavelength component image pickup device 107, a 4 × 2 8-band image can be taken in the same manner.
[0153]
In the first embodiment, the vertical position of the unit block is determined so that the first line of the unit block coincides with the scanning line of the image scanning. Therefore, the output signal of the imaging device is temporarily sent to the line memory. Therefore, it is possible to output in a stream format without holding the target and to accurately estimate the spectral information of the subject for each scanning line.
[0154]
In the first embodiment, the color separation optical system 102 includes a first optical prism 202 including a half mirror 203 that divides incident light into two optical paths, and one of the lights divided by the first optical prism 202. The second optical prism 209 including the dichroic mirror 210 that reflects only the short wavelength component, the third optical prism 216 that transmits the long wavelength component transmitted through the second optical prism 209, and the air gap 208 are included. As a result, the color separation optical system 102 that divides the luminance component and the two color components of the short wavelength and the long wavelength can be downsized to the volume of the three optical prisms. In addition, the point to be noted here is that the color separation optical system 102 includes three optical prisms as in the conventional color separation optical system composed of RGB. That is, the color separation optical system 102 according to the present embodiment can be created by slightly improving the conventional color separation optical system. Therefore, the color separation optical system 102 according to the present embodiment can be created from an existing material and can be easily applied to an existing imaging apparatus.
[0155]
In the first embodiment, the second optical prism 209 includes an infrared absorption filter 215 on the boundary surface from which the long wavelength component is output from the inside of the prism to the outside of the prism, so that imaging having sensitivity to infrared light is performed. Noise from the element can be suppressed with a simple configuration.
[0156]
(Embodiment 2)
A multiband video camera that is an imaging apparatus according to the second embodiment of the present invention will be described below. First, a system of a multiband video camera that simultaneously captures a multiband image with three image sensors in Embodiment 2 will be described with reference to FIG. FIG. 8 is a system configuration diagram of a multiband video camera that simultaneously captures a multiband image with the three image sensors in the second embodiment. The difference between FIG. 8 and FIG. 1 is the following two points, and others have the same configuration and the same operation and function.
[0157]
The first difference is that FIG. 8 does not have the lightness signal conversion unit 105 of FIG. The second difference is that the cell unit lightness signal replacement unit 114 in FIG. 1 is changed to a cell unit colorimetric value scaling unit 801.
[0158]
As described in detail with reference to FIG. 5, the cell unit lightness signal replacement unit 114 in FIG. 1 converts only the lightness of the colorimetric value from the colorimetric value conversion unit 112 into the lightness signal conversion unit 105 in the light receiving cell unit of the image sensor. Replaced with the lightness signal from. On the other hand, the cell unit colorimetric value scaling unit 801 in FIG. 8 scales the colorimetric values supplied from the colorimetric value conversion unit 802 in FIG. 8 using the luminance signal from the luminance signal generation unit 803.
[0159]
Next, the operation of the cell unit colorimetric value scaling unit 801 will be described in detail with reference to FIG. FIG. 9 shows a case where the unit block for spectral estimation of the subject is 2 cells in the vertical direction and 2 cells in the horizontal direction, as in FIG. The colorimetric value conversion unit 802 supplies the spectral reflectance r of the subject supplied by the subject spectral information estimation unit 804 in FIG. _h And the spectral distribution e of illumination supplied by the illumination spectral information storage unit 805 in FIG. _h CIEXYZ tristimulus values are calculated using equation (9). The output (X′Y′Z ′) of the colorimetric value conversion unit 802 is given to the cell unit colorimetric value scaling unit 801, and the cell unit luminance signal Y generated by the luminance generation unit 803 is used to obtain an expression (16 ) Scaling processing is performed.
[0160]
[Expression 16]

Therefore, the cell unit colorimetric value scaling unit 801 uses the cell unit scaling process to calculate the relative colorimetric value information (X′Y′Z ′) calculated for each unit block of spectral information estimation. It has a function of converting to absolute colorimetric value information (XYZ) in units.
[0161]
The primary color conversion unit 806 in FIG. 8 converts the CIEXYZ tristimulus value, which is the output of the cell unit colorimetric value scaling unit 801, into luminance linear device drive signals R, G, and B using Expression (13).
[0162]
As described above, according to the second embodiment, two types of color filters provided in the light receiving cells of the short wavelength component imaging device and the long wavelength component imaging device are reduced, while maintaining high resolution luminance component information with high resolution of the visual system. Multi-band images can be taken simultaneously with the image sensor, and still images and moving images can be taken of fast-moving subjects.
[0163]
(Embodiment 3)
Next, a multiband video camera that is an imaging apparatus according to the third embodiment of the present invention will be described.
[0164]
FIG. 10 shows a system configuration of a multiband video camera that simultaneously captures a multiband image with the three image sensors according to the third embodiment of the present invention, and will be described below in comparison with FIG. The difference between FIG. 1 and FIG. 10 is the following one point, and others have the same configuration and the same operation and function. 10 differs from FIG. 1 in that the gamma correction unit 117 of FIG. 1 is not provided in FIG.
[0165]
As described in detail with reference to FIG. 1, the gamma correction linearizes the non-linear characteristic between the device drive signal of the display device and the luminance of the display color. Since it is possible to cope with only the processing on the transmission side without mounting a special processing circuit on the display device, it is effective for simplification and cost reduction of the terminal device on the reception side.
[0166]
However, in recent years, high performance and cost reduction of electronic devices centering on semiconductor components have been greatly achieved, and it has become possible to provide various processing functions to the receiving terminal. In particular, display devices as computer terminals are utilized as video display devices for creating business graphics and computer graphics, and those having a function of generating a luminance linear signal by the display devices themselves have been increasing. The fusion of broadcasting and communications centering on the Internet has led to the demand for video display devices with two functions: televisions that display video with inverse gamma characteristics and computer visual terminals that display video with luminance linear signals. I made it.
[0167]
For this reason, when the receiving terminal has its own gamma correction function, the transmitting side does not need to perform gamma correction. The third embodiment is an imaging apparatus that outputs a video signal without applying gamma correction, and can supply accurate color information to a computer visual terminal or the like that performs gamma correction by the display device itself.
[0168]
As described above, according to the third embodiment, two types of color filters provided in the light receiving cells of the short wavelength component imaging device and the long wavelength component imaging device are reduced, while maintaining high resolution luminance component information with high resolving power in the visual system. Multi-band images can be taken simultaneously with the imaging device, still images and moving images can be taken of fast-moving subjects, and color signals without gamma correction can be supplied to image devices that do not require gamma correction.
[0169]
(Embodiment 4)
A multiband video camera that is an imaging apparatus according to Embodiment 4 of the present invention will be described below. FIG. 11 shows a system configuration of a multiband video camera that simultaneously captures a multiband image with two image sensors in Embodiment 4 of the present invention, and will be described below while comparing with the system configuration of FIG. The difference between FIG. 1 and FIG. 11 is the following three points, and others have the same configuration and the same operation and function.
[0170]
The first difference is in the color separation optical system. The color separation optical system 102 in FIG. 1 divides light from the subject incident from the imaging lens 101 into three optical paths, whereas the color separation optical system in FIG. Reference numeral 1101 denotes a point where light from a subject incident from the imaging lens 1102 is divided into two optical paths, and the light is distributed to a luminance imaging element 1103 and a color component imaging element 1104 described later.
[0171]
The second difference is an image sensor that captures the spectral information of the subject. In FIG. 1, the spectral information of the subject is estimated by two image sensors, the short wavelength component image sensor 106 and the long wavelength component image sensor 107 in FIG. In FIG. 11, the spectral information of the subject is estimated by one image sensor of the color component image sensor 1104.
[0172]
The third difference is the difference in the signal processing unit due to the single imaging device. The signal from the color component imaging device 1104 is input to the color component color signal processing unit 1105, and the subject spectral information estimation unit. The spectral estimation in 1106 is executed only by the output from the color component color signal processing unit 1105.
[0173]
Next, the color separation optical system 1101 will be described in detail with reference to FIG. A half mirror 1201 that divides incident light 1203 from the imaging lens 1102 into two optical paths is provided inside the color separation optical system 1101. The light in the first optical path divided by the half mirror 1201 is reflected light 1205 from the half mirror 1201. The half mirror 1201 is disposed so that the reflected light 1205 is perpendicularly incident on the luminance image sensor 1103. The light on the second optical path divided by the half mirror 1201 is transmitted light 1204 of the half mirror 1201. The half mirror 1201 is disposed so that the transmitted light 1204 is incident on the color component image sensor 1104 perpendicularly.
[0174]
As described above, the half mirror 1201 splits the incident light 1203 into the transmitted light 1204 and the reflected light 1205, the transmitted light 1204 enters the color component image sensor 1104, and the reflected light 1205 enters the luminance image sensor 1103.
[0175]
The half mirror 1201 has no wavelength selectivity, and the light 1204 and the light 1205 divided by the half mirror 1201 have the same spectral distribution.
[0176]
In addition, an infrared absorption filter 1202 is provided in parallel to the color component image sensor 1104 in the color component image sensor 1104 side with respect to the half mirror 1204 inside the color separation optical system 1101, that is, in the traveling direction of the transmitted light 1204. It has been. As a result, the transmitted light 1204 is noise-removed by the infrared absorption filter 1202 before being incident on the color component imaging device 1104.
[0177]
Next, the color component image sensor 1104 and the subject spectral information estimation unit 1106 will be described in detail. FIG. 13A is a diagram for explaining the arrangement of the color filters, and FIG. 13B is a diagram for explaining the arrangement of the color signals viewed in units of pixels.
[0178]
The color component imaging device 1104 is f ₁ To f ₉ Are provided in block units of 3 vertical cells and 3 horizontal cells. 9 color filters f ₁ To f ₉ Have different spectral transmittance distributions, for example, as shown in FIG. 14, nine have a relationship covering the visible region (from 380 nm to 780 nm in FIG. 14). That is, light in the entire visible range is received by the nine color filters.
[0179]
As described above, information for at least five bands is necessary for spectral estimation of a subject. For this reason, in order to form a band of five or more bands with the same number of square unit blocks in the vertical and horizontal directions, as shown in FIG. 13, three vertical cells and three horizontal cells are the minimum configuration.
[0180]
Then, the subject spectral information estimation unit 1106 receives the color filter f ₁ To f ₉ The spectral information of the subject is estimated based on these nine signals. Accordingly, the subject spectral estimation unit 1106 estimates and calculates the spectral information in units of blocks of 3 vertical cells and 3 horizontal cells.
[0181]
Compared with the configuration in which spectral estimation is performed with the two image sensors in FIG. 1, the spatial resolution of the color components drops to 1/3, but there is only one image sensor, and as shown in FIG. Since the system configuration is also simplified, it has significant advantages in terms of size and cost. In addition, as described above with reference to FIG. 7, if the spectral estimation unit block is moved in accordance with the image scanning, the influence of resolution reduction can be suppressed.
[0182]
As described above, according to the fourth embodiment, multiband images can be simultaneously obtained with one image sensor having fewer than the types of color filters provided in the light receiving cells of the color image sensor while maintaining high-resolution luminance component information with high resolving power in the visual system. It has the effect of being able to shoot still images and moving images of fast-moving subjects.
[0183]
Note that the lightness signal conversion unit 105 of the fourth embodiment may be omitted, and the cell unit lightness signal replacement unit 114 may be replaced with a cell unit colorimetric value scaling unit 801. With this configuration, luminance component information with high resolving power of the visual system is acquired with high definition by the luminance imaging device 1103, and colorimetric values acquired from the color component imaging device 1104 at the same time are obtained from the luminance component information from the luminance imaging device 1103. Can be scaled in units of light receiving cells. As a result, a multiband image can be simultaneously photographed with one image sensor that is smaller than the types of color filters provided in the light receiving cells of the color component image sensor 1104, and still images and moving images can be photographed for a fast-moving subject.
[0184]
(Embodiment 5)
A multiband video camera that is an imaging apparatus according to the fifth embodiment of the present invention will be described below with reference to FIG. FIG. 15 is a system configuration diagram of a multiband video camera that simultaneously captures a multiband image with the three image sensors in the fifth embodiment. The same parts as those already described are assigned the same reference numerals and the description thereof is omitted.
[0185]
The difference between the fifth embodiment and the first embodiment is that the luminance / color difference signal conversion unit 119 is changed to the brightness / color difference signal conversion unit 1501, and the luminance / color difference signal line memory 120 is changed to the brightness / color difference signal line memory 1502. The brightness / color difference signal transmitter 122 is a brightness / color difference signal transmitter 1503.
[0186]
The lightness / color difference signal converter 1501 converts the colorimetric value calculated by the cell unit lightness signal replacement unit 114 for each light receiving cell of the image sensor into a lightness component and a color difference component. Specifically, the lightness / color difference signal conversion unit 1501 first generates a luminance signal by a linear sum of a device drive signal or a luminance linear device drive signal that cancels the gamma characteristic of the video display device. Next, the lightness / color-difference signal conversion unit 1501 includes all the elements of the device drive signal or the luminance linear device drive signal except for the element that has the largest contribution rate to the luminance signal generation in the linear sum. The difference value obtained by subtracting the luminance signal is used as a color difference signal, the luminance signal is converted into a brightness signal by an exponential function, and the brightness signal and the color difference signal are output.
[0187]
Further, the brightness / color difference signal line memory 1502 and the brightness / color difference signal transmitter 1503 are used for the brightness / color difference signal line memory 120 and the brightness / color difference signal transmitter 122 of the first embodiment to handle the brightness signal. On the other hand, the brightness signal is handled, and the other operations are the same.
[0188]
As described above, according to the fifth embodiment, the colorimetric value in which the lightness is replaced in units of light receiving cells of the image sensor can be converted into lightness / color difference signals while maintaining the lightness linearity. In addition, the linearity of the brightness of the device drive signal and emission color is secured without providing a special processing unit in the video display device, and signal transmission with a brightness / color difference signal having a smaller band than the device drive signal is possible. Have the effect of
[0189]
In the fifth embodiment, the first embodiment has been described as a modified form. However, the luminance / color difference signal conversion unit 119 of the second to fourth embodiments is replaced with a brightness / color difference signal conversion unit 1501 for luminance / color difference signals. The line memory 120 may be modified to a brightness / color difference signal line memory 1502 and the luminance / color difference signal transmitter 122 may be modified to a brightness / color difference signal transmitter 1503.
[0190]
【The invention's effect】
As described above, the present invention estimates subject spectral information from one or two image sensors in which a plurality of color filters having different spectral transmittances are juxtaposed in units of light receiving cells, and acquires the subject in units of light receiving cells. An excellent imaging device that can output high-definition and high-color fidelity images by replacing or scaling the luminance information of the colorimetric values obtained from the spectral information of the subject in units of light-receiving cells. To do. In addition, by combining a half mirror and a dichroic mirror, light from the subject can be incident on one luminance image sensor and two color component image sensors with reduced light loss, and space is saved by combining three prisms. An excellent color separation optical system capable of realizing the above is provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a multiband video camera according to Embodiment 1 of the present invention.
FIG. 2 is a diagram for explaining the internal structure of the color separation optical system according to the first embodiment;
3A is a schematic structural view of a luminance imaging device, a short wavelength component imaging device, and a long wavelength component imaging device according to the first embodiment as viewed from the side surface. FIG.
(B) The conceptual diagram explaining the arrangement | sequence of the color filter of a brightness | luminance image sensor, a short wavelength component image sensor, and a long wavelength component image sensor concerning Embodiment 1. FIG.
(C) The arrangement of the color signal, the operation of the luminance conversion unit, and the operation of the subject spectral information estimation unit viewed from the luminance imaging device, the short wavelength component imaging device, and the long wavelength component imaging device according to the first embodiment. Conceptual diagram explaining
FIG. 4 is a diagram illustrating an example of spectral transmittance of the color filter according to the first embodiment;
FIG. 5 is a diagram for explaining operations of a colorimetric conversion unit, an illumination spectral information storage unit, a lightness signal conversion unit, and a cell unit lightness replacement unit according to the first embodiment;
FIG. 6A is a diagram showing the operation of the device drive signal line memory and the luminance / color difference signal line memory according to the first embodiment during scanning of the first scan line (unit block is fixed); If)
(B) The figure showing operation at the time of the second scanning line scan of the device drive signal line memory and the luminance / color difference signal line memory image according to the first embodiment (when the unit block is fixed)
FIG. 7A is a diagram showing the operation of the device drive signal line memory and the luminance / color difference signal line memory according to the first embodiment during the first scanning line scanning (unit blocks are used for image scanning); When moving accordingly)
FIG. 6B is a diagram illustrating the operation of the device drive signal line memory according to the first embodiment and the luminance / color difference signal line memory image during the second scan line scan (the unit block moves corresponding to the image scan). If)
FIG. 8 shows a configuration of a multiband video camera according to Embodiment 2 of the present invention.
FIG. 9 is a diagram for explaining the operation of the cell unit colorimetric value scaling unit according to the second embodiment;
10 shows a configuration of a multiband video camera according to Embodiment 3 of the present invention. FIG.
FIG. 11 is a diagram showing a configuration of a multiband video camera according to Embodiment 4 of the present invention.
FIG. 12 is a diagram showing an internal configuration of a color separation optical system according to a fourth embodiment.
FIG. 13A is a diagram for explaining a color filter array of a color component imaging device according to a fourth embodiment; FIG. 13B is a diagram illustrating an array of color signals in units of pixels and an operation of a subject spectral information estimation unit according to the fourth embodiment; Illustration
FIG. 14 shows nine color filters f according to the fourth embodiment. ₁ To f ₉ Of an example of spectral transmittance
FIG. 15 is a diagram showing a configuration of a multiband video camera according to Embodiment 5 of the present invention;
[Explanation of symbols]
101, 1102 Imaging lens
102, 1101 color separation optical system
103, 1103 luminance imaging device
104, 803, 1107 Luminance signal generator
105 Lightness signal converter
106 Short wavelength component image sensor
107 Long wavelength component image sensor
108 Short wavelength component color signal processing unit
109 Long wavelength component color signal processor
110, 804 Subject spectral information estimation unit
111 Spectral information output terminal
112, 802 Colorimetric value converter
113, 805 Illumination spectral information storage unit
114 cell unit lightness signal replacement unit
115 Colorimetric value output terminal
116, 806 Primary color conversion unit
117 Gamma correction unit
118 Line Memory for Device Drive Signal
119 Luminance / color difference signal converter
120 Line memory for luminance / color difference signals
121 Transmitter for device drive signal
122 Transmitter for luminance / color difference signal
201, 1203 Incident light from the imaging lens
202 1st optical prism
203, 1201 half mirror
204 First reflected light
205 First transmitted light
206 Surface of the first optical prism
207 Surface of the first optical prism
208 Air gap
209 Second optical prism
210 Long wavelength component reflection dichroic mirror
211 Second reflected light
212 Second transmitted light
213 Surface of the second optical prism
214 Surface of the second optical prism
215, 1202 Infrared absorption filter
216 Third optical prism
301 substrate
302 Light receiving cell
303 color filters
601 and 602 line memory
603, 604, 701 cells
801 Cell unit colorimetric scaling unit
1104 Color component imaging device
1105 Color component signal processing unit
1106 Subject spectral information estimation unit
1204 Transmitted light
1205 Reflected light
1501 Lightness / color difference signal converter

Claims (23)

A half mirror that splits the light from the imaging lens into two optical paths;
A luminance imaging element that receives one light divided by the half mirror and obtains luminance information of a subject ;
A luminance signal generation unit that generates and outputs a luminance signal from the luminance information;
A lightness signal converter for converting the luminance signal into a lightness signal;
A dichroic mirror that divides the other light divided by the half mirror into a short wavelength component and a long wavelength component;
A short wavelength component image sensor that receives the light of the short wavelength component through a plurality of different color filters at different light receiving cells and outputs a color signal corresponding to the received light;
The long wavelength component image sensor that receives the light of the long wavelength component by different light receiving cells through different color filters and outputs a color signal corresponding to the received light;
And subject spectral information estimation unit for estimating spectral information of the object from the color signal in which the said short-wavelength component image pickup device long wavelength component image sensor outputs,
A cell unit value signal replacement unit for replacing at the light receiving cell unit brightness information of colorimetric values calculated from the spectral information to the lightness signal brightness signal converting unit is converted,
An imaging apparatus comprising: A half mirror that splits the light from the imaging lens into two optical paths;
A luminance imaging element that receives one light divided by the half mirror and obtains luminance information of a subject ;
A luminance signal generation unit that generates and outputs a luminance signal from the luminance information;
A lightness signal converter for converting the luminance signal into a lightness signal;
A dichroic mirror that divides the other light divided by the half mirror into a short wavelength component and a long wavelength component;
A short wavelength component image sensor that receives the light of the short wavelength component through a plurality of different color filters at different light receiving cells and outputs a color signal corresponding to the received light;
The long wavelength component image sensor that receives the light of the long wavelength component by different light receiving cells through different color filters and outputs a color signal corresponding to the received light;
And subject spectral information estimation unit for estimating spectral information of the object from the color signal in which the said short-wavelength component image pickup device long wavelength component image sensor outputs,
A cell unit colorimetric value scaling unit for scaling the colorimetric value calculated from the spectral information in units of the light receiving cell by the luminance signal;
An imaging apparatus comprising: The arrangement of the color filter of the entire short-wavelength component image pickup device has a repeating pattern of unit block consisting of a plurality of adjacent light receiving cell,
The color filters of the short wavelength component image sensor have different spectral transmittance distributions in the unit block, and when the spectral transmittance distributions of all the color filters in the unit block are combined, the short wavelength component Covering the wavelength band of light ,
The imaging apparatus according to claim 1 or 2, wherein Arrangement of the color filter of the entire long-wavelength component image pickup device has a repeating pattern of unit block consisting of a plurality of adjacent light receiving cell,
The color filters of the long wavelength component image sensor have different spectral transmittance distributions in the unit block, and when the spectral transmittance distributions of all the color filters in the unit block are combined, the long wavelength component Covering the wavelength band of light ,
The imaging apparatus according to claim 1 or 2, wherein A half mirror that splits the light from the imaging lens into two optical paths;
A luminance imaging element that receives one light divided by the half mirror and obtains luminance information of a subject ;
A luminance signal generation unit that generates and outputs a luminance signal from the luminance information;
A lightness signal converter for converting the luminance signal into a lightness signal;
A color imaging element that receives the other light divided by the half mirror by a plurality of different light receiving cells through different color filters and outputs a color signal corresponding to the received light;
And subject spectral information estimation unit for estimating spectral information of the object from the color signal,
Of the colorimetric value calculated from the spectral information, a cell unit value signal replacement portion only brightness information the lightness signal converting unit replaced with said receiving cell units converted brightness information,
An imaging apparatus comprising: A half mirror that splits the light from the imaging lens into two optical paths;
A luminance imaging element that receives one light divided by the half mirror and obtains luminance information of a subject ;
A luminance signal generation unit that generates and outputs a luminance signal from the luminance information;
A lightness signal converter for converting the luminance signal into a lightness signal;
A color imaging element that receives the other light divided by the half mirror by a plurality of different light receiving cells through different color filters and outputs a color signal corresponding to the received light;
And subject spectral information estimation unit for estimating spectral information of the object from the color signal,
A cell unit colorimetric value scaling unit for scaling the colorimetric value calculated from the spectral information in units of the light receiving cell by the luminance signal;
An imaging apparatus comprising: The color image sensor receives light through a color filter for each light receiving cell of the image sensor,
The color filter, as a plurality of adjacent light receiving cell unit blocks has a different spectral transmittance distribution in the unit block, and the wavelength band that is incident from all combining the imaging lens color filters of the unit block With spectral transmittance distribution covering
Arrangement of the color filter of the entire color image sensor has a repeating pattern of said unit blocks,
The imaging device according to claim 5 or 6, wherein The unit block consists of 2 vertical cells and 2 horizontal cells.
The subject spectral information estimation unit estimates spectral information of a subject for each unit block .
The imaging apparatus according to claim 3, wherein the imaging apparatus is characterized by that. The vertical position of the unit block is determined so that the first line of the unit block coincides with the scanning line of image scanning .
The imaging apparatus according to claim 3, wherein the imaging apparatus is characterized by that. The unit block is composed of n vertical cell,
Storing an external output signal corresponding to (n-1) lines in the unit block in a line memory, and outputting the external output signals from the second line in the unit block from the line memory ;
The imaging apparatus according to claim 3, wherein the imaging apparatus is characterized by that. An illumination spectral information storage unit that stores illumination spectral information;
Anda colorimetric value conversion unit for calculating a colorimetric value of the object using the spectral information of the illumination that is held in the illumination spectral data storage unit,
The cell unit lightness signal replacement unit or the cell unit colorimetric value scaling unit obtains the spectral information of the subject estimated by the subject spectral information estimation unit and the colorimetric value information from the colorimetric value conversion unit .
The imaging apparatus according to any one of claims 1, 2, 5, and 6. The cell unit lightness signal replacement unit or cell unit colorimetric value scaling unit is:
A primary color conversion unit that converts a colorimetric value calculated for each light receiving cell into a luminance linear drive level of a display device;
A gamma correction unit for correcting gamma characteristics of the display device from the output of the primary color conversion unit;
A luminance / color difference signal conversion unit for calculating a luminance / color difference signal from the output of the gamma correction unit;
Claim 1, characterized by comprising, claim 2, imaging device according to any one of claims 5 and 6. The cell unit lightness signal replacement unit or cell unit colorimetric value scaling unit is:
A primary color conversion unit that converts a colorimetric value calculated for each light receiving cell into a luminance linear drive level of a display device;
A luminance / color difference signal conversion unit for calculating a luminance / color difference signal from the output of the primary color conversion unit;
Claim 1, characterized by comprising, claim 2, imaging device according to any one of claims 5 and 6. Cell unit value signal replacement unit or units of cells colorimetric value scaling unit,
A lightness / color difference signal converter for converting the colorimetric value calculated for each light receiving cell into a lightness component and a color difference component ;
Claim 1, characterized by comprising, claim 2, imaging device according to any one of claims 5 and 6. The luminance / color difference signal conversion unit generates a luminance signal by a linear sum of a device drive signal or a luminance linear device drive signal that cancels gamma characteristics of the video display device, and configures the device drive signal or the luminance linear device drive signal. Among the elements, a difference value obtained by subtracting the luminance signal from each of the elements excluding the element having the largest contribution rate to luminance signal generation in the linear sum is used as a color difference signal, and the luminance signal and the color difference signal are output. ,
The imaging apparatus according to claim 12 or claim 13, The brightness / color difference signal conversion unit generates a luminance signal by a linear sum of a device drive signal or a luminance linear device drive signal that cancels the gamma characteristic of the video display device, and configures the device drive signal or the luminance linear device drive signal. Among the elements, the difference value obtained by subtracting the luminance signal from each of the elements excluding the element having the largest contribution rate to the luminance signal generation in the linear sum is used as a color difference signal, and the luminance signal is represented by an exponential function. To output the lightness signal and the color difference signal ,
The imaging apparatus according to claim 14. When the device drive signal that cancels the gamma characteristics of the video display device consists of three bands of R, G, and B, or when the luminance linear device drive signal consists of three bands of R, G, and B, the contribution ratio of the R band is The luminance signal is calculated by a linear sum with 0.30, the G band contribution ratio of 0.59, and the B band contribution ratio of 0.11 .
The imaging apparatus according to claim 15 or claim 16, wherein When the device drive signal that cancels the gamma characteristic of the video display device consists of three bands of R, G, and B, or when the luminance linear device drive signal consists of three bands of R, G, and B, the contribution ratio of the R band is The luminance signal is calculated by a linear sum of 0.299, the contribution rate of the G band is 0.587, and the contribution rate of the B band is 0.114 .
The imaging apparatus according to claim 15 or claim 16, wherein When the device drive signal that cancels the gamma characteristics of the video display device consists of three bands of R, G, and B, or when the luminance linear device drive signal consists of three bands of R, G, and B, the contribution ratio of the R band is The luminance signal is calculated by a linear sum of 0.2126, the G band contribution ratio is 0.7152, and the B band contribution ratio is 0.0722 .
The imaging apparatus according to claim 15 or claim 16, wherein The half mirror and the dichroic mirror are included in a color separation optical system,
The color separation optical system is
A first optical prism comprising the half mirror that divides incident light into two optical paths;
A second optical prism comprising the dichroic mirror that reflects only the short wavelength component of the one light split by the first optical prism;
A third optical prism that transmits the long wavelength component transmitted by the second optical prism;
An air gap between the first optical prism and the second optical prism;
The imaging apparatus according to claim 1 , further comprising: The third optical prism includes an infrared absorption filter on a boundary surface where a long wavelength component is output from the inside of the prism to the outside of the prism .
The imaging apparatus according to claim 20. The half mirror and the dichroic mirror are included in a color separation optical system,
The color separation optical system is
A first optical prism comprising the half mirror that divides incident light into two optical paths;
A second optical prism comprising the dichroic mirror that reflects only the long-wavelength component of one of the lights divided by the first optical prism;
A third optical prism that transmits the short wavelength component transmitted by the second optical prism;
An air gap between the first optical prism and the second optical prism;
The imaging apparatus according to claim 1 , further comprising: The second optical prism includes an infrared absorption filter on a boundary surface where the reflected long wavelength component is output from the inside of the prism to the outside of the prism .
The imaging apparatus according to claim 22.

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