JP2019092003A - Signal processing device and imaging apparatus - Google Patents

Abstract

To provide a signal processing device and an imaging apparatus capable of achieving a high image quality of an imaging image, and an imaging apparatus.SOLUTION: A signal processing device includes: a first photoelectric conversion layer photoelectrically converting light of a prescribed wavelength; and a second photoelectric conversion layer provided closer to a side on which incident light is incident than the first photoelectric conversion layer and photoelectrically converting light having a wavelength different from that of the first photoelectric conversion layer, and processes signals of red, green, and blue generated in an imaging apparatus that generates the signals of red, green, and blue by the photoelectric conversion. The signal processing device further comprises: an adsorption correction part that performs adsorption correction processing of correcting a light component of the wavelength photoelectrically converted in the first photoelectric conversion layer which is adsorbed in the second photoelectric conversion layer, on at least some of the signals of red, green, and blue; and a color correction part that performs color correction procession on the basis of the signals of red, green, and blue after the adsorption correction processing performed on the at least some of the signals.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a signal processing device and an imaging device.

  There has been developed a photoelectric conversion film stack type solid-state imaging device having “a configuration in which a photoelectric conversion film is stacked on a semiconductor substrate on which a photoelectric conversion element is formed”. Examples of the technology related to the photoelectric conversion film laminated type solid-state imaging device include the technology described in Patent Document 1 below and the technology described in Patent Document 2 below.

Unexamined-Japanese-Patent No. 2006-120773 Unexamined-Japanese-Patent No. 2006-210497

  For example, a photoelectric conversion member used in an imaging device such as a digital camera has been developed using a single material of silicon (Silicon). However, when a single material of silicon is used, the band gap (Band Gap) is fixed, and a color filter (Filter) can be configured only on the surface. Therefore, in an imaging device having a photoelectric conversion member using a single material of silicon, color imaging can not be performed with a single plate other than arranging red pixels, green pixels, and blue pixels in the plane direction. . Hereinafter, red may be indicated as “R” (Red), green as “G” (Green), and blue as “B” (Blue).

  Also, when an object having a high resolution is imaged by the imaging device having the photoelectric conversion member as described above, luminance moiré and color moiré occur. In order to suppress the generated luminance moiré and color moiré, it is necessary to dispose an optical low pass filter in the imaging device. However, in the case of arranging an optical low pass filter in an imaging device, there is a disadvantage that a reduction in resolution is caused.

  Here, if a photoelectric conversion film laminated type solid-state imaging device as described in, for example, Patent Documents 1 and 2 is used, "ameliorate the defects which may occur in the imaging device having the photoelectric conversion member as described above" It is possible.

  However, when a photoelectric conversion film laminated type solid-state imaging device is used, “a light component of a wavelength photoelectrically converted by a photoelectric conversion layer is partially separated by another photoelectric conversion layer closer to the incident light incident side "Absorbed" can occur. When such a situation occurs, for example, problems such as deterioration of color reproducibility, deterioration of noise resistance of color areas such as blue areas, and deterioration of resolution occur. Further, in the existing technologies such as the technologies described in Patent Documents 1 and 2, no consideration is given to the above problem.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved signal processing apparatus capable of achieving high image quality of a captured image, and an imaging apparatus. It is to provide.

  In order to achieve the above object, according to one aspect of the present invention, a first photoelectric conversion layer that photoelectrically converts light of a predetermined wavelength, and a side on which incident light is incident than the first photoelectric conversion layer Provided in the imaging device having the first photoelectric conversion layer and the second photoelectric conversion layer for photoelectrically converting light of a different wavelength, and generating a red signal, a green signal, and a blue signal by photoelectric conversion A signal processing apparatus for processing a red signal, a green signal, and a blue signal, wherein the second photoelectric conversion layer absorbs light of a wavelength to be photoelectrically converted in the first photoelectric conversion layer. An absorption correction unit that performs an absorption correction process for correcting light components on at least a portion of the red signal, the green signal, and the blue signal; The above absorption correction process is performed After, the red signal, based on the green signal, and the blue signal, comprising a color correction unit that performs color correction processing, the signal processing device is provided.

  With this configuration, it is possible to perform the color correction process after correcting in advance the known absorption characteristics of the signals (red signal, green signal, and blue signal) indicating the captured image generated in the imaging device. Therefore, with such a configuration, it is possible to achieve high image quality of a captured image.

  In the imaging device, green light is photoelectrically converted in the second photoelectric conversion layer to generate the green signal, and red light and blue light are photoelectrically converted in the first photoelectric conversion layer. The red signal and the blue signal are generated, and the absorption correction unit performs the absorption correction process on each of the green signal and the blue signal based on the green signal and the blue signal. Alternatively, the absorption correction process may be performed on each of the green signal and the red signal based on the green signal and the red signal.

  The absorption correction unit determines a first correction value corresponding to the blue light component absorbed by the second photoelectric conversion layer based on the green signal and the blue signal, and determines the first correction value. The second signal corresponding to the red light component absorbed by the second photoelectric conversion layer is corrected based on the green signal and the blue signal, or based on the green signal and the red signal. A correction value may be determined, and the green signal and the red signal may be corrected by the second correction value.

  The absorption correction unit subtracts the first correction value from the green signal and adds the first correction value to the blue signal to correct the green signal and the blue signal. Alternatively, the second correction value may be subtracted from the green signal, and the second correction value may be added to the red signal to correct each of the green signal and the red signal.

  In the imaging device, green light is photoelectrically converted in the second photoelectric conversion layer to generate the green signal, and red light and blue light are photoelectrically converted in the first photoelectric conversion layer. A first interpolation unit for generating the red signal and the blue signal and interpolating one of the red signal and the blue signal; and a first interpolator for the red signal and the blue signal. And a second interpolation unit that interpolates a signal of the other color, the first interpolation unit interpolates the signal of the one color based on the green signal, and the absorption correction unit The absorption correction process is performed on the green signal on the basis of the signal of 1 and the one color signal interpolated, and the second interpolation unit performs the absorption correction process on the signal of the other color. The above green belief after being done The color correction unit interpolates the color correction process based on the interpolated red signal, the green signal after the absorption correction process is performed, and the blue signal interpolated. You may

  In order to achieve the above object, according to another aspect of the present invention, a first photoelectric conversion layer that photoelectrically converts light of a predetermined wavelength, and incident light is incident from the first photoelectric conversion layer. An imaging unit that is provided on the side and has a second photoelectric conversion layer that photoelectrically converts light of a wavelength different from the first photoelectric conversion layer, and generates a red signal, a green signal, and a blue signal by photoelectric conversion And an absorption correction process for correcting the light component of the wavelength photoelectrically converted in the first photoelectric conversion layer absorbed in the second photoelectric conversion layer, the red signal, the green signal, and the blue signal. An absorption correction unit for performing at least a part of the signals, and the red signal, the green signal, and the blue signal after the absorption correction process is performed on at least a part of the signals. Perform color correction processing based on the Comprising a color correction unit, the imaging device is provided.

  With this configuration, the color correction process may be performed after correcting in advance the known absorption characteristics of the signals (red signal, green signal, and blue signal) indicating the captured image generated by imaging in the imaging unit. it can. Therefore, with such a configuration, it is possible to achieve high image quality of a captured image.

  According to the present invention, it is possible to achieve high image quality of a captured image.

It is an explanatory view showing roughly an example of the 1st photoelectric conversion layer and the 2nd photoelectric conversion layer. It is an explanatory view showing an example of processing in a signal processing device concerning a 1st embodiment. It is an explanatory view showing an example of a result of absorption amendment processing concerning an embodiment of the present invention. It is an explanatory view showing an example of processing assumed when absorption amendment processing is not performed. FIG. 5 is an explanatory view showing an example of a circuit for realizing a process assumed when the absorption correction process shown in FIG. 4 is not performed. It is explanatory drawing which shows an example of the circuit for implement | achieving the process in the signal processing apparatus which concerns on 1st Embodiment shown in FIG. It is explanatory drawing which shows the example of reduction of the circuit scale of the circuit shown in FIG. 6 with respect to the circuit shown in FIG. It is an explanatory view showing an example of processing in a signal processing device concerning a 2nd embodiment. It is explanatory drawing which shows notionally the interpolation process shown to C of FIG. 8, the absorption correction process shown to D of FIG. 8, and the interpolation process shown to E of FIG. FIG. 9 is an explanatory drawing showing an example of a circuit for realizing the interpolation processing shown in C of FIG. 8, the absorption correction processing shown in D of FIG. 8, and the interpolation processing shown in E of FIG. 8.

  The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. In the present specification and the drawings, components having substantially the same functional configuration will be assigned the same reference numerals and redundant description will be omitted.

  Also, in the following, a signal processing apparatus according to an embodiment of the present invention (hereinafter sometimes simply referred to as “signal processing apparatus”) will be mainly described. The signal processing apparatus may be configured to include an imaging unit. The imaging unit includes, for example, an image sensor (Image Sensor) including a first photoelectric conversion layer described later and a second photoelectric conversion layer described later. Further, the imaging unit may be configured to include a lens of an optical system. The signal processing apparatus including the imaging unit functions as an imaging apparatus according to the embodiment of the present invention.

[1] Outline of Signal Processing Device According to Embodiment of the Present Invention The signal processing device is a device that processes a signal generated by imaging in an imaging device, that is, a signal indicating a captured image.

  As a signal produced | generated by imaging in an imaging device, a red signal, a green signal, and a blue signal are mentioned, for example. The signal generated by imaging in the imaging device includes, for example, a signal obtained as a result of photoelectric conversion of light of the wavelength of NIR (Near-infrared), that is, a signal indicating a so-called infrared image. It is also good.

  The imaging device includes, for example, a first photoelectric conversion layer and a second photoelectric conversion layer, and generates a red signal, a green signal, and a blue signal by photoelectric conversion.

  The first photoelectric conversion layer is a photoelectric conversion layer that photoelectrically converts light of a predetermined wavelength. The second photoelectric conversion layer is a photoelectric conversion layer that photoelectrically converts light of a wavelength different from that of the first photoelectric conversion layer. The second photoelectric conversion layer is provided closer to the incident light than the first photoelectric conversion layer. When the direction in which incident light is incident is defined as “upper direction”, the second photoelectric conversion layer corresponds to the upper layer, and the first photoelectric conversion layer corresponds to the lower layer. That is, the imaging device is a stacked imaging device in which a plurality of photoelectric conversion layers are stacked.

  A transparent electrode formed of, for example, ITO (Indium Tin Oxide) or the like is provided between the first photoelectric conversion layer and the second photoelectric conversion layer. Examples of the first photoelectric conversion layer include a substrate formed of silicon and provided with a photoelectric conversion element. The transparent electrode is electrically connected to a circuit formed on the substrate. Moreover, as a 2nd photoelectric converting layer, an organic film is mentioned, for example.

  FIG. 1 is an explanatory view schematically showing an example of a first photoelectric conversion layer and a second photoelectric conversion layer. L1 shown in FIG. 1 shows an example of the first photoelectric conversion layer, and L2 shown in FIG. 1 shows an example of the second photoelectric conversion layer.

  In the example shown in FIG. 1, R pixels and B pixels are formed by a conventional semiconductor process using silicon (first photoelectric conversion layer L1). The R pixel and the B pixel are arranged in a checkered pattern, for example. Needless to say, the example of the arrangement of the R pixel and the B pixel is not limited to the checkered pattern.

  Further, in the example illustrated in FIG. 1, an organic photoelectric film that absorbs light of the G wavelength is disposed on the upper layer of the substrate on which the B pixels and the R pixels are formed (second photoelectric conversion layer L2) .

  In the configuration shown in FIG. 1, since G pixels are present for all the pixels, theoretically no luminance moiré occurs and color moiré is also significantly suppressed.

  However, in the configuration shown in FIG. 1, when a material having a high external quantum efficiency of G is used as the second photoelectric conversion layer L2, not only the light of the G wavelength but also the light of the B wavelength or the R wavelength Light is also partially absorbed, and photoelectric conversion is performed. And when processing is performed using only the signal photoelectrically converted in each of the first photoelectric conversion layer L1 and the second photoelectric conversion layer L2, the color reproducibility is deteriorated and the noise resistance of the B region or R region is deteriorated. Problems such as deterioration of resolution occur.

  In addition, the example of a 1st photoelectric converting layer and a 2nd photoelectric converting layer is not restricted to the example shown in FIG.

  For example, the first photoelectric conversion layer may be formed by a conventional semiconductor process in which R pixels, G pixels, and B pixels are made of silicon. In this case, the R pixels, the G pixels, and the B pixels are arranged, for example, in a Bayer arrangement.

  The second photoelectric conversion layer may be an NIR layer that absorbs light of the NIR wavelength and performs photoelectric conversion.

  Even when the first photoelectric conversion layer and the second photoelectric conversion layer have the other configuration described above, the same problem as the configuration shown in FIG. 1 may occur.

  As described above, when processing is performed using only the signal photoelectrically converted in each of the first photoelectric conversion layer and the second photoelectric conversion layer, problems such as deterioration in color reproducibility may occur.

  Therefore, the signal processing device performs absorption correction processing on a signal generated by imaging in the imaging device. More specifically, the signal processing device performs an absorption correction process on at least a part of the red signal, the green signal, and the blue signal. Then, the signal processing device performs the color correction process based on the red signal, the green signal, and the blue signal after the absorption correction process is performed on at least a part of the signals.

  The absorption correction process according to the embodiment of the present invention is “a process of correcting a light component of a wavelength which is absorbed in the second photoelectric conversion layer and photoelectrically converted in the first photoelectric conversion layer”. That is, the signal processing apparatus can reduce the influence of “the light component of the wavelength photoelectrically converted in the lower layer, which is absorbed in the upper layer” by performing the absorption correction process. An example of the absorption correction process will be described later.

  The absorption correction process is performed, for example, in an absorption correction unit included in the signal processing device. As an absorption correction part, the processor which comprises a signal processing apparatus, an image processing circuit etc. are mentioned, for example.

  Further, as the color correction process according to the embodiment of the present invention, for example, a process of performing fine adjustment of color by matrix operation using a color correction matrix can be mentioned. An example of the color correction process will be described later.

  The color correction processing is performed, for example, in a color correction unit provided in the signal processing apparatus. As a color correction part, the processor which comprises a signal processing apparatus, an image processing circuit, etc. are mentioned, for example. The processor or the like that functions as the color correction unit and the processor or the like that functions as the absorption correction unit may be the same as or different from each other.

  The signal processing device performs the color correction processing after performing the absorption correction processing on the signal generated by the imaging in the imaging device. That is, the signal processing device performs color correction processing after correcting in advance the known absorption characteristics.

  Therefore, the signal processing device has a problem such as “deterioration of color reproducibility, deterioration of noise resistance in region B or region R, deterioration of resolution, etc., which may occur when an existing photoelectric conversion film stack type solid-state imaging device is used. The effect of “can be made smaller. Therefore, the signal processing apparatus can achieve high image quality of a captured image.

  Hereinafter, processing in the signal processing device according to the embodiment of the present invention will be more specifically described.

  Below, the case where a 1st photoelectric converting layer and a 2nd photoelectric converting layer are the structures shown in FIG. 1 is mentioned as an example. Also, in the following, an example in which the signal processing device performs the absorption correction process on each of the green signal and the blue signal or on the green signal based on the green signal and the blue signal is exemplified. Listed. Note that “the signal processing device can perform absorption correction processing on each of the green signal and the red signal or on the green signal based on the green signal and the red signal. Needless to say, The signal processing device can also perform absorption correction processing on each of the green signal, the red signal, and the blue signal based on the green signal, the red signal, and the blue signal.

[2] First Embodiment The signal processing device according to the first embodiment is an example of “a device that performs color correction processing after previously correcting a known absorption characteristic”.

[2-1] Processing in Signal Processing Device According to First Embodiment The signal processing device according to the first embodiment performs, for example, the following processing (A) and the following processing (B).
(A) The signal processing device transmits a green signal from the second photoelectric conversion film L2 that absorbs blue light or red light and a signal corresponding to the color of light absorbed by the second photoelectric conversion film L2. Absorption correction is performed before color correction processing is performed.
(B) The signal processing device performs color correction processing based on the signal obtained as a result of the absorption correction.

  In the signal processing apparatus according to the first embodiment, the process of (A) is performed by the absorption correction unit. In the signal processing apparatus according to the first embodiment, the process (B) is performed by a color correction unit.

  FIG. 2 is an explanatory view showing an example of processing in the signal processing device according to the first embodiment. FIG. 2A shows an example of the red signal Rin, the green signal Gin, and the blue signal Bin. The red signal Rin, the green signal Gin, and the blue signal Bin correspond to signals to be processed by the signal processing device according to the first embodiment. Moreover, B of FIG. 2 has shown an example of a structure of a 1st photoelectric converting layer and a 2nd photoelectric converting layer, and corresponds to the 1st photoelectric converting layer L1 shown in FIG. 1, and the 2nd photoelectric converting layer L2. C of FIG. 2 shows an example of the absorption correction process in the signal processing device according to the first embodiment. And D of FIG. 2 has shown an example of the color correction process in the signal processing apparatus concerning 1st Embodiment.

[2-1-1] One Example of Absorption Correction Processing Shown in C of FIG. 2 The signal processing device according to the first embodiment has a light component of a wavelength corresponding to blue light absorbed by the second photoelectric conversion layer L2. Are corrected by the absorption correction process. In the signal processing apparatus according to the first embodiment, the absorption correction process shown in C of FIG. 2 is performed by, for example, an absorption correction unit.

  FIG. 3 is an explanatory view showing an example of the result of the absorption correction process according to the embodiment of the present invention. FIG. 3A shows an example of the red signal Rin, the green signal Gin, and the blue signal Bin. FIG. 3B shows an example of a red signal Rin ′, a green signal Gin ′, and a blue signal Bin ′ obtained as a result of the absorption correction process.

  The signal processing device according to the first embodiment determines the first correction value based on the green signal and the blue signal. The first correction value according to the embodiment of the present invention is a correction value corresponding to the blue light component absorbed by the second photoelectric conversion layer L2.

Examples of the first correction value include the following example. It goes without saying that the first correction value is not limited to the example shown below.
Bottom Gbottom in the blue region of the green signal
・ Absorptivity G0 of green light at a wavelength indicating the peak value Bpeak of the blue signal

  When the first correction value is determined, the signal processing device according to the first embodiment corrects each of the green signal and the blue signal with the first correction value.

  The signal processing apparatus according to the first embodiment corrects the green signal by subtracting the first correction value from the green signal, for example, as shown in Equation 1 below or Equation 2 below.

Gin '= Gin-Gbottom
... (Equation 1)

Gin '= Gin-G0
... (Equation 2)

  In addition, the signal processing apparatus according to the first embodiment corrects a blue signal by adding the first correction value to the blue signal, as shown in, for example, Equation 3 below or Equation 4 below.

Bin '= Bin + Gbottom
... (Equation 3)

Bin '= Bin + G0
... (Equation 4)

  The absorption correction process according to the embodiment of the present invention is not limited to the example described above. For example, the signal processing apparatus according to the first embodiment may correct each of the green signal and the blue signal as shown in the following Equation 5 and Equation 6, for example.

Gin '= Gin-a * Bin / (1-a)
... (Equation 5)

Bin '= Bin / (1-a)
... (Equation 6)

  Here, “a” shown in Equation 5 and Equation 6 is determined, for example, in consideration of the blue light component absorbed by the second photoelectric conversion layer L2. As an example, as "a" shown to the said Numerical formula 5 and the said Numerical formula 6, the absorptivity G0 of green light is mentioned.

  As described above, the signal processing apparatus according to the first embodiment can also correct the light component of the wavelength corresponding to the red light absorbed by the second photoelectric conversion layer L2 by the absorption correction process. It is. In this case, the signal processing device according to the first embodiment determines the second correction value based on the green signal and the red signal. Then, the signal processing apparatus according to the first embodiment corrects each of the green signal and the red signal by the second correction value, as in the correction using the first correction value, for example.

The second correction value according to the embodiment of the present invention is a correction value corresponding to the red light component absorbed by the second photoelectric conversion layer L2. Examples of the second correction value include the following example. It goes without saying that the second correction value is not limited to the example shown below.
・ Bottom Gbottom 'in the red area of the green signal
-Green light absorptivity G0 'at a wavelength indicating the peak value Rpeak of the red signal

  Further, the signal processing apparatus according to the first embodiment may correct each of the green signal and the red signal as shown in, for example, Equation 7 and Equation 8 below.

Gin '= Gin-a'Rin / (1-a')
... (Equation 7)

Rin '= Rin / (1-a')
... (Equation 8)

  Here, “a ′” shown in the equation 7 and the equation 8 is determined in consideration of, for example, the red light component absorbed by the second photoelectric conversion layer L2. As an example, as "a '" shown to said Numerical formula 7 and said Numerical formula 8, the absorptivity G0' of green light is mentioned.

[2-1-2] One Example of Color Correction Process Shown in D of FIG. 2 The signal processing apparatus according to the first embodiment performs the color correction process based on the signal obtained as a result of the absorption correction. In the signal processing apparatus according to the first embodiment, the color correction process shown in D of FIG. 2 is performed by, for example, a color correction unit.

  The signal processing apparatus according to the first embodiment performs matrix calculation using a color correction matrix based on a signal obtained as a result of absorption correction as shown in, for example, Equation 9 below, and performs color fine adjustment. The three operations shown in Equation 9 below are represented by, for example, a 3 × 3 matrix. In addition, Equation 9 below is an example of matrix calculation using a color correction matrix when the light component of the wavelength corresponding to the blue light absorbed in the second photoelectric conversion layer L2 is corrected by the absorption correction processing. It shows. Needless to say, the example of the color correction process is not limited to the matrix operation using the color correction matrix.

[2-2] Example of Effects of First Embodiment The signal processing apparatus according to the first embodiment performs color correction processing after previously correcting known absorption characteristics. Therefore, as described above, the signal processing apparatus according to the first embodiment can achieve high image quality of a captured image.

  The effects of the signal processing device according to the first embodiment are not limited to the examples described above. Next, an example of the effect of the first embodiment will be described in comparison with processing assumed when absorption correction processing is not performed.

  FIG. 4 is an explanatory view showing an example of processing assumed when absorption correction processing is not performed. Similarly to A of FIG. 2, A of FIG. 4 illustrates an example of the red signal Rin, the green signal Gin, and the blue signal Bin. Moreover, B of FIG. 4 has shown an example of a structure of a 1st photoelectric converting layer and a 2nd photoelectric converting layer similarly to B of FIG. C of FIG. 4 shows an example of processing assumed when absorption correction processing is not performed.

  As processing assumed when absorption correction processing is not performed, for example, matrix operation processing using a color correction matrix as shown in the following Equation 10 can be mentioned. In addition, in the processing assumed when the absorption correction processing is not performed, white balance processing may be further performed.

  Here, when the absorption correction process is not performed, in order to reduce the influence of the blue light component (or the red light component) absorbed by the second photoelectric conversion layer L2, the amount of absorption is changed to a color correction matrix. It is necessary to correct in the matrix operation process used. In that case, it is necessary to make the respective coefficients C00, C10,..., C21, C22 shown in the above equation 10 larger and more accurate than the coefficients shown in the above equation 9.

  Then, "the fact that the coefficient in the matrix operation using the color correction matrix becomes larger and the higher precision is required" leads to an increase in circuit scale.

  FIG. 5 is an explanatory view showing an example of the circuit 10 for realizing the processing assumed when the absorption correction processing shown in FIG. 4 is not performed. The circuit 10 includes, for example, multipliers 12, 14, 16, 18, 20, 22, 24, 26, 28 for multiplying the coefficients C00, C10,. It consists of 32 and 34.

  FIG. 6 is an explanatory diagram showing an example of a circuit 100 for realizing the processing in the signal processing device according to the first embodiment shown in FIG. The circuit 100 includes, for example, multipliers 104, 106, 108, 110, 112, 114, 116, 118, 120 for multiplying the absorption correction circuit 102 and the coefficients C00, C10,. And adders 122, 124, 126. The absorption correction circuit 102 includes, for example, a shift adder 130 (Shift Adder) and an adder 132.

  Here, comparing the circuit 10 shown in FIG. 5 with the circuit 100 shown in FIG. 6, the circuit 100 has a configuration in which the absorption correction circuit 102 is added to the configuration of the circuit 10. Therefore, the circuit 100 appears to be larger in circuit scale than the circuit 10 by the addition of the absorption correction circuit 102.

  However, in practice, the shift adder 130 constituting the absorption correction circuit 102 is a small scale circuit (for example, several hundreds of gates).

  Further, in the configuration of the circuit 100 shown in FIG. 6, the values of the coefficients C01, C02, C10, C12, C20 and C21 shown in the equation 9 are small, and it is guaranteed that they are values near zero. Further, in the configuration of the circuit 100 shown in FIG. 6, it is ensured that the values of the coefficients C00, C11 and C22 shown in the equation 9 are in the vicinity of one. Therefore, in the configuration of the circuit 100 shown in FIG. 6, the number of bits of each of the multipliers 104, 106, 108, 110, 112, 114, 116, 118, and 120 can be reduced.

As an example, if all the multipliers in the circuit 10 shown in FIG. 5 require an accuracy of about 12 bits, the multipliers constituting the circuit 100 shown in FIG. is there.
· Multipliers 106, 108, 110, 114, 116, 118 corresponding to the coefficients C01, C02, C10, C12, C20, C21: about positive and negative 8 bits · Multipliers 104, 112, 120 corresponding to the coefficients C00, C11, C22 : A positive value 8 bits or so near 1

  FIG. 7 is an explanatory view showing an example of reduction of the circuit scale of the circuit 100 shown in FIG. 6 with respect to the circuit 10 shown in FIG.

  For example, as shown in FIG. 7, the signal processing apparatus according to the first embodiment significantly reduces the circuit scale by correcting in advance the color correction that has been performed only by the matrix operation and the known absorption characteristics. be able to.

[3] Second Embodiment The signal processing device according to the second embodiment is another example of “a device that performs color correction processing after previously correcting a known absorption characteristic”. The main difference between the second embodiment and the first embodiment is that “the signal processing apparatus according to the second embodiment performs absorption correction processing before interpolation of a red signal or a blue signal. It is a point.

[3-1] Processing in Signal Processing Device According to Second Embodiment The signal processing device according to the second embodiment performs, for example, the processing of the following (a) to the processing of the following (d).
(A) Development of a pixel of one color mainly absorbed by the second photoelectric conversion layer L2 among red or blue (b) absorption correction processing of green that is photoelectrically converted in the second photoelectric conversion layer L2 (C) Perform the development of the other color pixel not developed in (a) among the red and blue signals (d) Perform color correction processing

  In the signal processing device according to the second embodiment, the process of (a) is performed by the first interpolation unit. Further, in the signal processing apparatus according to the second embodiment, the process (b) is performed by the absorption correction unit. Further, in the signal processing device according to the second embodiment, the processing of (c) is performed by the second interpolation unit. In the signal processing apparatus according to the second embodiment, the process (d) is performed by the color correction unit.

  As a 1st interpolation part, the processor which comprises a signal processing apparatus, an image processing circuit etc. are mentioned, for example. Moreover, as a 2nd interpolation part, the processor which comprises a signal processing apparatus, an image processing circuit etc. are mentioned, for example. Further, as each of the absorption correction unit and the color correction unit, similarly to the signal processing apparatus according to the first embodiment, a processor that configures the signal processing apparatus, an image processing circuit, and the like can be given. The first interpolation unit, the absorption correction unit, the second interpolation unit, the processor functioning as the color correction unit, and the like may be the same or at least partially different.

  Hereinafter, an example of processing in the signal processing device according to the second embodiment will be described by taking as an example the case where the color absorbed mainly by the second photoelectric conversion layer L2 is blue. That is, in the example of the process shown below, “the process when the pixel of one color shown in the above (a) is a blue pixel and the pixel of the other color shown in the above (c) is a red pixel An example. Note that even if “the pixel of one color shown in (a) is a red pixel and the pixel of the other color shown in (c) is a blue pixel”, the second embodiment The signal processing apparatus according to the present invention can perform processing in the same manner as the processing described below.

  FIG. 8 is an explanatory view showing an example of processing in the signal processing device according to the second embodiment. Similarly to A of FIG. 2, A of FIG. 8 illustrates an example of the red signal Rin, the green signal Gin, and the blue signal Bin. Moreover, B of FIG. 8 has shown an example of a structure of a 1st photoelectric converting layer and a 2nd photoelectric converting layer similarly to B of FIG. C in FIG. 8 shows an example of interpolation processing for interpolating a blue signal. In addition, D in FIG. 8 illustrates an example of the absorption correction process in the signal processing device according to the second embodiment. Further, E in FIG. 8 shows an example of interpolation processing for interpolating a red signal. And F of FIG. 8 has shown an example of the color correction process in the signal processing apparatus concerning 2nd Embodiment.

[3-1-1] An example of the interpolation process shown in C of FIG. 8, the absorption correction process shown in D of FIG. 8, and the interpolation process shown in E of FIG. It is explanatory drawing which shows notionally the absorption correction process shown to D of FIG. 8, and the interpolation process shown to E of FIG.

  As shown in A of FIG. 9, the signal processing apparatus according to the second embodiment first performs interpolation on the blue signal Bin. When the red pixels and the blue pixels are arranged in a checkered pattern, there are red pixels and blue pixels in which no pixel value exists. Therefore, the signal processing apparatus according to the second embodiment first interpolates the blue signal Bin. It goes without saying that the signal processing apparatus according to the second embodiment can first perform interpolation on the red signal Rin. In the signal processing apparatus according to the second embodiment, the process shown in A of FIG. 9 is performed by, for example, a first interpolation unit.

  The signal processing apparatus according to the second embodiment performs interpolation on the blue signal Bin, for example, with reference to the gradient of the pixel value of the green pixel indicated by the green signal Gin. The reason for performing interpolation with reference to the gradient of the pixel value of the green pixel is, for example, that pixel values exist in all the green pixels, the images of the respective colors are correlated, and the green has the highest contribution to luminance. It is. In addition, since the green signal Gin contains the blue light component absorbed by the second photoelectric conversion layer L2, it is appropriate to perform interpolation with reference to the gradient of the pixel value of the green pixel. It can be said that it is interpolation.

  When interpolation is performed on the blue signal Bin, the signal processing apparatus according to the second embodiment determines that the green signal is based on the green signal Gin and the interpolated blue signal as shown in B of FIG. The absorption correction process is performed on Gin. In the signal processing apparatus according to the second embodiment, the process shown in B of FIG. 9 is performed by, for example, an absorption correction unit.

  The signal processing apparatus according to the second embodiment performs the absorption correction process as in the case of the absorption correction process in the signal processing apparatus according to the first embodiment. Therefore, by performing the absorption correction process on the green signal Gin, a green signal having high color reproducibility is generated.

  When the absorption correction process is performed on the green signal Gin, the signal processing apparatus according to the second embodiment performs interpolation on the red signal Rin as shown in C of FIG. In the signal processing device according to the second embodiment, the process shown in C of FIG. 9 is performed by, for example, a second interpolation unit.

  The signal processing apparatus according to the second embodiment performs interpolation on the red signal Rin, for example, with reference to the gradient of the pixel value of the green pixel indicated by the green signal after the absorption correction processing has been performed. In the pixel value of the green pixel after the absorption correction processing is performed, the influence of the blue light component absorbed by the second photoelectric conversion layer L2 is removed. Therefore, by performing interpolation with reference to the gradient of the pixel value of the green pixel after the absorption correction processing has been performed, the adverse effect of the gradient of the pixel value of the blue pixel on the interpolation of the red signal Rin is reduced can do.

  FIG. 10 is an explanatory view showing an example of a circuit 150 for realizing the interpolation process shown in C of FIG. 8, the absorption correction process shown in D of FIG. 8, and the interpolation process shown in E of FIG. The circuit 150 includes, for example, a Blue / Red holding line memory (Line Memory) 152, a Green holding line memory 154, a write counter (Write Counter) 156, a read counter (Read Counter) 158, and a Blue interpolation circuit 160. It comprises a Blue holding line memory 162, a Blue absorption correction circuit 164, a Green holding line memory 166, and a Red interpolation circuit 168.

  The Blue / Red holding line memory 152 is a line memory for holding each of the blue signal Bin and the red signal Rin. The Green holding line memory 154 is a line memory for holding a green signal Gin.

  Writing to each of the Blue / Red holding line memory 152 and the Green holding line memory 154 is controlled by the write counter 156. Further, reading from each of the Blue / Red holding line memory 152 and the Green holding line memory 154 is controlled by the read counter 158.

  The write counter 156 and the read counter 158 perform counting based on, for example, a change in signal level of a synchronization signal transmitted from a processor (not shown) or the like configuring the signal processing apparatus according to the second embodiment. The write counter 156 and the read counter 158 respectively control the Blue / Red holding line memory 152 and the Green holding line memory 154 according to the count value. The control method of each of the write counter 156 and the read counter 158 is not particularly limited as long as the process described with reference to FIG. 9 can be realized.

  The Blue interpolation circuit 160 interpolates the blue signal Bin read from the Blue / Red holding line memory 152. The Blue interpolation circuit 160 interpolates the blue signal Bin with reference to the gradient of the pixel value of the green pixel indicated by the green signal Gin read from the Green holding line memory 154.

  The Blue holding line memory 162 is a line memory for holding an interpolated blue signal Bin 'obtained as a result of processing in the Blue interpolation circuit 160. The Blue holding line memory 162 functions as a delay element that delays the output of the interpolated blue signal Bin 'by a time synchronized with the output of the green signal or the output of the red signal, for example.

  The Blue absorption correction circuit 164 performs an absorption correction process on the green signal Gin based on the green signal Gin read from the Green holding line memory 154 and the interpolated blue signal Bin ′. Examples of the Blue absorption correction circuit 164 include an absorption correction circuit 102 shown in FIG.

  The Green holding line memory 166 is a line memory for holding a green signal Gin 'obtained as a result of processing in the Blue absorption correction circuit 164. The Green holding line memory 166 functions as a delay element for delaying the output of the green signal Gin 'by the time synchronized with the output of the blue signal Bin'.

  The Red interpolation circuit 168 interpolates the red signal Rin read from the Blue / Red holding line memory 152. The Red interpolation circuit 168 performs interpolation on the red signal Rin while referring to the gradient of the pixel value of the green pixel indicated by the green signal Gin ′ read out from the Green holding line memory 166.

  For example, an interpolated red signal Rin ', a green signal Gin' after absorption correction processing, and an interpolated blue signal Bin 'are obtained by the circuit 150 configured as shown in FIG. The circuit configuration for realizing the interpolation process shown in C of FIG. 8, the absorption correction process shown in D of FIG. 8, and the interpolation process shown in E of FIG. 8 is not limited to the example shown in FIG. Needless to say.

[3-1-2] Color Correction Process Shown in F of FIG. 8 The signal processing apparatus according to the second embodiment includes the interpolated red signal, the green signal after the absorption correction process is performed, and the interpolation Color correction processing is performed based on the received blue signal. The signal processing apparatus according to the second embodiment performs color correction processing as in the color correction processing in the signal processing apparatus according to the first embodiment. In the signal processing apparatus according to the second embodiment, the color correction process shown in F of FIG. 8 is performed by, for example, a color correction unit.

[3-2] Example of Effects of Second Embodiment The signal processing apparatus according to the second embodiment executes known absorption characteristics within the process related to interpolation and corrects known absorption characteristics in advance. Above, color correction processing is performed. Therefore, as described above, the signal processing apparatus according to the second embodiment can achieve high image quality of a captured image.

[4] Application Example of Signal Processing Device According to Embodiment of the Present Invention The signal processing device according to the embodiment of the present invention is, for example, “computer such as PC (Personal Computer) or server (Server)” The present invention can be applied to any device capable of processing an image signal obtained by imaging in an image sensor having a plurality of photoelectric conversion layers, such as a tablet type device. Further, the signal processing device according to the embodiment of the present invention can also be applied to, for example, an IC (Integrated Circuit) that can be incorporated into the above-described device.

  Further, as described above, the signal processing apparatus according to the embodiment of the present invention includes an imaging unit including an image sensor having the first photoelectric conversion layer and the second photoelectric conversion layer (an example of the plurality of photoelectric conversion layers). And may function as an imaging device. In this case, the imaging device according to the embodiment of the present invention is, for example, an image of a “Digital Still Camera”, a “Digital Video Camera”, a “smartphone”, a mobile phone, etc. It can be applied to any device having a function.

  Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the appended claims, and of course these also fall within the technical scope of the present invention. It is understood.

10, 100, 150 circuits 12, 14, 16, 18, 20, 22, 24, 26, 28, 104, 106, 108, 110, 112, 114, 116, 118, 120 multipliers 30, 32, 34, 122 , 124, 126, 132 Adder 102 Absorption Correction Circuit 130 Shift Adder 152 Blue / Red Holding Line Memory 154, 166 Green Holding Line Memory 156 Light Counter 158 Read Counter 160 Blue Interpolation Circuit 162 Blue Holding Line Memory 164 Blue Absorption Correction Circuit 168 Red Interpolation Circuit L1 First photoelectric conversion layer L2 Second photoelectric conversion layer

Claims (6)

A first photoelectric conversion layer that photoelectrically converts light of a predetermined wavelength, and a side closer to the incident light than the first photoelectric conversion layer are provided to photoelectrically convert light of a wavelength different from that of the first photoelectric conversion layer Processing a red signal, a green signal, and a blue signal that are generated in an imaging device that has a second photoelectric conversion layer and generates a red signal, a green signal, and a blue signal by photoelectric conversion A signal processing device,
Absorption correction processing for correcting a light component of a wavelength photoelectrically converted in the first photoelectric conversion layer absorbed in the second photoelectric conversion layer, the red signal, the green signal, and the blue signal An absorption correction unit for at least a part of the signals
A color correction unit that performs color correction processing based on the red signal, the green signal, and the blue signal after the absorption correction processing has been performed on at least a part of the signals;
A signal processing apparatus comprising: In the imaging device, green light is photoelectrically converted in the second photoelectric conversion layer to generate the green signal, and red light and blue light are photoelectrically converted in the first photoelectric conversion layer to produce the red light. And the blue signal is generated,
The absorption correction unit
Performing the absorption correction process on each of the green signal and the blue signal based on the green signal and the blue signal, or
The signal processing device according to claim 1, wherein the absorption correction process is performed on each of the green signal and the red signal based on the green signal and the red signal. The absorption correction unit
A first correction value corresponding to the blue light component absorbed by the second photoelectric conversion layer is determined based on the green signal and the blue signal, and the green signal and the green signal are determined according to the first correction value. Correct each blue signal, or
A second correction value corresponding to the red light component absorbed by the second photoelectric conversion layer is determined based on the green signal and the red signal, and the green signal and the green signal are determined according to the second correction value. The signal processing apparatus according to claim 2, wherein each of the red signals is corrected. The absorption correction unit
The first correction value is subtracted from the green signal, and the first correction value is added to the blue signal to correct the green signal and the blue signal, or
The signal according to claim 3, wherein the second correction value is subtracted from the green signal, and the second correction value is added to the red signal to correct each of the green signal and the red signal. Processing unit. In the imaging device, green light is photoelectrically converted in the second photoelectric conversion layer to generate the green signal, and red light and blue light are photoelectrically converted in the first photoelectric conversion layer to produce the red light. And the blue signal is generated,
A first interpolation unit that interpolates a signal of one of the red signal and the blue signal;
A second interpolation unit that interpolates a signal of the other of the red signal and the blue signal;
And further
The first interpolation unit interpolates the one color signal based on the green signal,
The absorption correction unit performs the absorption correction process on the green signal based on the green signal and the one color signal interpolated.
The second interpolation unit interpolates the signal of the other color based on the green signal after the absorption correction process is performed,
The color correction unit performs the color correction processing based on the interpolated red signal, the green signal after the absorption correction processing is performed, and the interpolated blue signal. The signal processing device according to 1. A first photoelectric conversion layer that photoelectrically converts light of a predetermined wavelength, and a side closer to the incident light than the first photoelectric conversion layer are provided to photoelectrically convert light of a wavelength different from that of the first photoelectric conversion layer An imaging unit having a second photoelectric conversion layer and generating a red signal, a green signal, and a blue signal by photoelectric conversion;
Absorption correction processing for correcting a light component of a wavelength photoelectrically converted in the first photoelectric conversion layer absorbed in the second photoelectric conversion layer, the red signal, the green signal, and the blue signal An absorption correction unit for at least a part of the signals
A color correction unit that performs color correction processing based on the red signal, the green signal, and the blue signal after the absorption correction processing has been performed on at least a part of the signals;
An imaging device comprising:

Images