JP2005198091A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct variation in an optical magnification of an imaging lens without making a lens barrel part large in size. <P>SOLUTION: A magnification correction section 35 comprises a correction magnification arithmetic section 40 and an image magnification section 41. The correction magnification arithmetic section 40 detects a size of a mask aperture of a film mask 26 from an image represented by image data outputted from a CCD area sensor 28 and detects a magnification variation amount from a setting magnification of the imaging lens on the basis of the detected size. When the detected magnification variation amount is deviated from a range of permissible magnification variation amounts, the correction magnification arithmetic section 40 calculates a correction magnification used for the magnification processing on the basis of the detected magnification variation amount. The image magnification section 41 applies the magnification processing to a frame image read from the CCD area sensor 28 at this correction magnification. Thus, the image reading apparatus corrects variations in the optical magnification caused by temperature changes in the imaging lens. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus that photoelectrically reads an image of a read original such as a photographic film and outputs image data.

JP-A-9-152540 Japanese Patent Laid-Open No. 9-113785

  An image reading device that photoelectrically reads an image recorded on a photographic film and outputs digital image data; a printer device that exposes an image on photosensitive recording paper with recording light that is intensity-modulated based on the image data; A digital printing system including a processor device that generates a printed photograph by performing development / drying processing on recording paper is widely used. The image reading apparatus includes a CCD sensor as a photoelectric conversion means, an imaging lens that forms an image of light from a photographic film on the photoelectric surface of the CCD sensor, and an image processing unit that corrects image data output from the CCD sensor. Is done.

  From the viewpoint of downsizing the imaging lens and suppressing chromatic aberration as much as possible, a lens element made of low dispersion glass is preferably used. Although this low dispersion glass has small chromatic aberration, it has a characteristic that the optical magnification is likely to fluctuate because changes in expansion coefficient and refractive index with respect to temperature are higher than those of normal glass. In view of this, a variation in optical magnification is corrected by measuring the temperature in the vicinity of the imaging lens and moving only the imaging lens based on the detected temperature (see Patent Documents 1 and 2).

  In the apparatus described in the above-mentioned patent document, a moving mechanism such as a cam mechanism is incorporated in the lens barrel in order to enable movement of the imaging lens, so that the lens barrel portion is enlarged and the manufacturing cost is increased. There is a problem that it ends up.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an image reading apparatus capable of correcting fluctuations in optical magnification without increasing the size of the apparatus.

  In order to achieve the above object, an image reading apparatus according to the present invention includes an image sensor, an imaging lens, and a film mask, detects size information of an image represented by image data from the image sensor, and uses the size information to detect the image pickup lens. Based on the detected magnification fluctuation amount, the magnification fluctuation amount detecting means for detecting the magnification fluctuation amount of the image pickup lens is calculated, and the correction magnification for correcting the magnification fluctuation from the set magnification of the imaging lens is calculated. Image scaling means for performing a scaling process is provided.

  The magnification variation detecting means preferably detects the size of the area defined by the reading frame of the film mask as size information from the image represented by the image data. It is preferable that the image scaling unit performs a scaling process for correcting the variation of the optical magnification only when the detected magnification variation is out of the range of the allowable magnification variation. Further, it is preferable to perform the scaling process at a magnification obtained by multiplying the correction magnification by an absolute magnification set according to the print size. The calculation of the correction magnification can be performed at any given time interval before, during or after reading the recorded frame image.

  It is preferable that the image data used for the detection of the size information by the magnification variation detection means is read and output by the image sensor after performing autofocus. The magnification variation detection means can also read the scale value of the chart attached around the reading frame from the image represented by the image data, and detect the magnification variation amount from the set magnification of the imaging lens from the scale value. .

  According to the present invention, based on the magnification variation amount of the imaging lens obtained by detecting the size information of the image represented by the image data, the correction magnification for correcting the magnification variation from the set magnification of the imaging lens is calculated, Since the scaling process is performed on the image data, the fluctuation of the optical magnification can be corrected without providing a mechanism for moving the imaging lens. Therefore, the apparatus can be reduced in size and the cost can be reduced.

  Only when the detected magnification fluctuation amount is out of the range of the allowable magnification fluctuation amount, the magnification processing for correcting the optical magnification variation is performed, so that the time required for calculating the correction magnification can be shortened. Furthermore, since the scaling process is performed at a magnification obtained by multiplying the correction magnification by the absolute magnification set according to the print size, it is possible to prevent the occurrence of moire in the corrected image.

  As shown in FIG. 1, the digital laboratory system 10 includes an image reading device 11 and an image output device 12. The image reading device 11 includes a light source 13, a diffusion box 14, a film carrier 15, an imaging unit 16, and the like, which are arranged on an optical axis 17 of the imaging unit 16.

  The light source 13 has a number of light emitting diodes (LEDs) 13R, 13G, 13B, and 13IR that emit red (R), green (G), blue (B), and infrared (IR) light in a matrix on a substrate 13a. It is arranged and configured. The LEDs 13R, 13G, 13B, and 13IR are controlled to emit light by the LED driver 42. At the time of image reading to be described later, R, G, B, IR light (reading light) is sequentially irradiated toward the photographic film 18 by causing each LED 13R, 13G, 13B, 13IR to emit light individually for each color. . Reference numeral 19 denotes a protective cover made of a transparent material such as plastic, and prevents the LEDs 13R, 13G, 13B, and 13IR from being damaged. A fan 20 is provided in the vicinity of the light source 13, and the LEDs 13R, 13G, 13B, and 13IR are cooled so as to be within a predetermined temperature range, thereby suppressing variations in emission intensity due to temperature variations.

  Diffusion plates 21 and 22 for diffusing light are provided on the lower surface and the upper surface of the diffusion box 14, respectively. The R, G, B, and IR light emitted from each of the LEDs 13R, 13G, 13B, and 13IR is diffused by the diffusion plate 21 disposed on the lower surface and is incident on the diffusion box 14. The incident light is guided upward while being reflected by the inner surface, is diffused again by the diffusion plate 22, and is irradiated toward the photographic film 18 set on the film carrier 15. As a result, the photographic film 18 is irradiated with reading light having a substantially uniform light amount over the surface thereof.

  The film carrier 15 is provided for each type of photographic film 18 to be conveyed, and these are selected and set at the reading position of the image reading apparatus 11. For example, a 135 type film carrier 15 has a transport path 23 for transporting a 135 type photographic film 18, and an exposure opening 24 is formed in a portion overlapping the optical axis 17. At the time of image reading, a film transport mechanism (not shown) transports the photographic film 18 and positions each photographing frame at the exposure opening 24.

  As shown in FIG. 2, the film carrier 15 is provided with a lower mask 25 at the lower portion and an upper mask 26 at the upper portion at a position corresponding to the exposure opening 24. These masks 25 and 26 are formed in a frame shape having mask openings 25a and 26a. The mask opening 26a is a reading frame for the CCD area sensor 28 to read a frame image, and exposes the frame image. As is well known, the upper mask 26 is retracted above the photographic film 18 while the photographic film 18 is being conveyed. Further, when reading an image, it moves downward to sandwich the photographic film 18 at the reading position together with the lower mask 25 to ensure its flatness.

  As shown in FIG. 1, the imaging unit 16 includes a lens unit 27, a CCD area sensor 28, a lens barrel 29, a support plate 30, a guide rod 31, and the like. The lens unit 27 is composed of a plurality of low dispersion lenses having small chromatic aberration, and is held inside the lens barrel 29. The lens barrel 29 is attached to the support plate 30. A CCD area sensor 28 is attached to the support plate 30 in the lens barrel 29.

  The guide rod 31 is composed of a male screw, and a focus adjustment motor 32 driven by an autofocus driver 43 is attached to the guide rod 31. The guide rod 31 is screwed into the support plate 30, and when the guide rod 31 is rotated by the focus adjustment motor 32, the support plate 30 moves in the direction of the optical axis 17. The movement of the support plate 30 changes the distance (conjugate length) between the photographic film 18 and the CCD area sensor 28 and performs focus adjustment (autofocus function). By this focus adjustment, the imaging frames illuminated with light emitted from the LEDs 13R, 13G, 13B, and 13IR are imaged on the photoelectric surface of the CCD area sensor 28.

  The CCD area sensor 28 is driven by a CCD driver (not shown), converts an optical image formed on the photocathode into an electrical imaging signal, and outputs it. The imaging signal is amplified by an amplifier (not shown), converted to a digital signal by the A / D converter 33, and sent to the image signal correction unit 34. Instead of the CCD area sensor 28, various known image sensors and line sensors may be used.

  The image signal correction unit 34 performs signal processing such as shading correction and dark current correction on the image signal input from the A / D converter 33, and sends the corrected image signal to a magnification correction unit 35 described later. . In this way, image reading is performed in which each photographing frame optically recorded on the photographic film 18 is read as digital image data.

  Image reading is performed twice: prescan and fine scan. In pre-scanning, the photographic film 18 is conveyed in one direction and an image is read with a low number of pixels. In fine scanning, the photographic film 18 is sent in the opposite direction opposite to one direction, and the image is read with a high number of pixels. It is done. The image processing unit 36 sets a reading condition based on pre-scan data for each photographing frame during fine scanning. In each scan, the color LEDs 13R, 13G, 13B, and 13IR of the light source 13 are turned on for each color, and R, G, B, and IR scan image data are obtained sequentially for each color.

  Image data obtained by each scanning process is sent to the image processing unit 36 via the magnification correction unit 35. The image processing unit 36 sets the reading conditions for the fine scan process for the image data obtained by the prescan process. For image data obtained by fine scan processing, for example, gradation conversion, color conversion, hypertone processing for compressing the gradation of the ultra-low frequency luminance component of the image, hyper for emphasizing sharpness while suppressing graininess Image processing such as sharpness processing is performed. The image data for which image processing has been completed is displayed on the monitor 37 as a finished image so that the operator can confirm it. If there is no problem in observing the monitor screen, the operator operates a print key (not shown) to instruct printing. As a result, the R, G, B image data for which image processing has been completed is sent to the image output device 12 as R, G, B output image data. Thereafter, image processing of each captured frame image is performed in the same manner.

  The image output device 12 includes a laser print unit 38 and a processor unit 39. The laser print unit 38 includes R, G, and B laser light sources and a modulation unit. The modulation unit modulates each color laser beam from the laser light source based on the output image data of R, G, and B sent from the image processing unit 36, and scans and exposes color paper with the modulated laser beam. The image (latent image) is recorded on color paper. The processor unit 39 performs color development, bleach-fixing, washing with water, and drying on color paper that has been subjected to scanning exposure. In this way, a photographic print is obtained from the photographic frame recorded on the photographic film 18.

  Here, when the optical characteristics of the lens unit 27 change due to temperature fluctuation, the optical magnification of the read image after autofocusing fluctuates. That is, as shown in FIG. 3, the image range 52 of the photographic frame of the photographic film 18 is deviated from the predetermined trimming range 51 in the imaging range 50 of the CCD area sensor 28. In the example of FIG. 3, since the trimming range 51 is larger than the frame image range 52, a margin portion is generated at the edge of the read image obtained by trimming.

  In the present embodiment, the size of the mask opening 26 a of the upper mask 26 is detected as size information from the image represented by the image data output from the CCD area sensor 28. Then, from this size information, the magnification fluctuation amount from the set magnification of the lens unit 27 is detected. When the reading magnification amount is out of the allowable magnification variation range, a correction magnification for correcting the variation of the optical magnification of the lens unit 27 is calculated, and the magnification processing is performed on the read frame image data. Thereby, the variation of the optical magnification due to the temperature variation of the lens unit 27 is corrected.

  The magnification correction unit 35 includes a correction magnification calculation unit 40 and an image scaling unit 41. From the image read by the CCD area sensor 28 after the light source 13 is turned on and autofocusing is performed at the mask opening 26a, for example, the correction magnification calculator 40 The size of the mask opening 26a is detected. Then, the magnification variation amount of the lens unit 27 is detected from the size of the mask opening 26a, and it is determined whether or not the detected magnification variation amount is within the range of the allowable magnification variation amount. When the detected magnification fluctuation amount is in the range of the allowable magnification fluctuation amount, the absolute magnification C0 set according to the print size is written in the memory 40a provided in the correction magnification calculator 40 as the correction magnification.

  On the other hand, when the detected magnification fluctuation amount is out of the range of the allowable magnification fluctuation amount, the first correction magnification C1 is calculated based on the detected magnification fluctuation amount. At this time, the monitor 37 displays a message to the effect that correction of the magnification fluctuation due to the temperature change is performed. After calculating the first correction magnification C1, this is multiplied by the absolute magnification C0 to calculate a second correction magnification C2, and this second correction magnification C2 is written in the memory 40a as the correction magnification. After that, a scaling process is performed on the read frame image data at the magnification written as the correction magnification in the memory 40a. For example, the correction magnification is calculated once for each film process for reading all the shot frame images of the photographic film 18.

  The image scaling unit 41 performs scaling processing on each image data obtained by fine scan processing. During this scaling process, the correction magnification written in the memory 40a of the correction magnification calculator 40 is read, and image scaling is performed with the read correction magnification.

  Since the variation amount of the optical magnification of the lens unit 27 is not large, moire tends to occur when image magnification is performed at the first correction magnification C1. For this reason, the image scaling unit 41 performs zooming with the second correction magnification C2 that is calculated by multiplying the relatively large absolute magnification C0 by the first correction magnification C1. As a result, it is possible to effectively suppress moiré that may occur when the scaling process is simply performed at the first correction magnification C1. Furthermore, since it is not necessary to perform the scaling process a plurality of times, the time required for the arithmetic processing can be shortened.

  Next, the procedure of the image reading process will be described with reference to the flowcharts of FIGS. After the film carrier 15 on which the photographic film 18 is not yet set is set in the image reading apparatus 11, a correction magnification calculation process for correcting a variation in optical magnification caused by a temperature change of the lens unit 27 is performed. In the correction magnification calculation process, first, the light source 13 is turned on, the focusing is performed on the mask opening 26a, and then the image is read by the CCD area sensor 28. The correction magnification calculation unit 40 detects the size of the mask opening 26a as size information from this image, and detects the magnification fluctuation amount R1 of the lens unit 27 from this size information.

  If the detected magnification fluctuation amount R1 is within the allowable magnification fluctuation amount range, the absolute magnification C0 based on the print size is written in the memory 40a. On the other hand, when outside the range of the allowable magnification fluctuation amount, the first correction magnification C1 is calculated based on the detected magnification fluctuation amount R1, and the second correction magnification C2 obtained by multiplying the correction magnification C1 by the set magnification C0. Is calculated and written to the memory 40a.

  Next, the photographic film 18 is set on the film carrier 15 and the image reading process is started. In the image reading process, first, a pre-scan process for reading an image roughly is performed. The read frame image obtained by the pre-scan process is sent to the image processing unit 36, and reading conditions such as the aperture amount are determined based on the obtained image information.

  After the pre-scan process, a fine scan process is performed. The read frame image by the fine scan processing is sent to the image scaling unit 41. The image scaling unit 41 performs a scaling process on the image data obtained by the fine scan process. During this scaling process, the correction magnification (second correction magnification C2 or set magnification C0) is read from the memory 40a of the correction magnification calculator 40, and the size of the read frame image is changed with this correction magnification. .

  The image data that has undergone the scaling process is sent to the image processing unit 36. The image processing unit 36 performs various kinds of image processing on the image data and then displays the image data on the monitor 37. The operator gives an instruction to print if there is no problem by observing the screen of the monitor 37. The image data instructed to be printed is sent to the image output device 12. Thereafter, image reading processing, image scaling processing, and image processing of each captured frame image are performed in the same manner.

  In the above-described embodiment, the image for size information detection is read after performing autofocus at the mask opening 26a in a state where the photographic film 18 is not in the exposure opening 24. However, autofocus is performed in the negative area of the photographic film. After this is done, an image for detecting size information may be read. In addition, an image for detecting size information may be read simultaneously with the reading of the base density performed by the image signal correction unit 34 or the like.

  In the above-described embodiment, the correction magnification calculation process is performed before the pre-scan process of the first scanned frame image. However, the timing of the correction magnification calculation process is not limited to this, and at the time of image reading during the pre-scan process Alternatively, at the time of image reading in the fine scan process, it may be performed between the pre-scan process and the fine scan process and after the fine scan process.

  In the above embodiment, the correction magnification calculation process is performed once for each film process. However, this process may be performed at regular time intervals and performed a plurality of times for each film process.

  In the above embodiment, the size information is described by taking the size of the mask opening 26a as an example, but the size information is not limited to this. For example, the size of the frame image may be detected from the difference in the density of the image data. Further, as shown in FIG. 6, a chart 64 may be attached around the mask opening 63a, and the scale value of the chart 64 may be read as size information. In this case, it is preferable that the chart 64 is configured to be attachable so that the chart 64 is retracted from the imaging range 60 during image reading.

  In the above embodiment, the zoom process for correcting the fluctuation of the optical magnification is performed by the second correction magnification C2 obtained by multiplying the first correction magnification C1 by the absolute magnification C0. However, the occurrence of moire is avoided. If possible, the second correction magnification C2 is not necessarily used, and the first correction magnification C1 may be used.

  In the above embodiment, the operator is notified by displaying a message on the monitor 37 that the correction of the magnification variation of the lens unit 27 is to be performed. However, the lamp may be turned on or an alarm sound may be generated. .

  In the above embodiment, the reading of the frame image recorded on the photographic film has been described as an example. However, the present invention also applies to the case where the image data is generated by reading the image recorded on the transparent original or the reflective original. Can be applied to.

It is explanatory drawing which shows the structure of a digital laboratory system roughly. It is the schematic which shows the reading optical system at the time of calculating correction magnification. It is explanatory drawing which shows the state from which the read image range imaged on a CCD area sensor changed with the temperature characteristics of the imaging lens. It is a flowchart which shows the procedure of an image reading process. It is a flowchart which shows the procedure of a correction magnification calculation process. It is explanatory drawing which shows the other form of an upper mask.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Digital laboratory system 11 Image reader 18 Photo film 26 Upper mask 26a Mask opening 27 Lens unit 28 CCD area sensor 35 Magnification correction part 40 Correction magnification calculation part 41 Image magnification part

Claims (7)

An image sensor that optically reads frame images recorded on a photographic film and outputs them as image data;
An imaging lens that forms an image on the photocathode of the imaging device with light irradiated on the frame image;
In an image reading apparatus comprising a film mask having a reading frame that exposes the frame image in a readable manner,
Magnification variation detection means for detecting size information of an image represented by the image data, and detecting a magnification variation from a set magnification of the imaging lens from the size information;
Based on the magnification fluctuation amount detected by the magnification fluctuation amount detecting means, a correction magnification for correcting the optical magnification fluctuation caused by the temperature change of the imaging lens is calculated, and the image data is subjected to the magnification processing with the correction magnification. An image reading apparatus comprising an image scaling unit for performing the operation.   The image reading apparatus according to claim 1, wherein the magnification variation detection unit detects a size of an area defined by the reading frame from the image represented by the image data as the size information.   3. The image scaling unit according to claim 1, wherein the image scaling unit performs a scaling process for correcting a variation in optical magnification only when the detected magnification variation amount is out of a range of the allowable magnification variation amount. The image reading apparatus described.   4. The image scaling unit according to claim 1, wherein the image scaling unit performs a scaling process at a magnification obtained by multiplying the correction magnification by an absolute magnification set according to a print size. Image reading device.   5. The image according to claim 1, wherein the calculation of the correction magnification by the image scaling unit is performed at any time interval before, during or after the reading of the recorded frame image. Reader. It has an autofocus function that automatically focuses on the reading frame,
6. The image data used for detection of size information by the magnification variation detection unit is read and output by the image sensor after performing autofocus. The image reading apparatus described. Attach a chart around the reading frame,
The magnification change amount detection unit reads a scale value of the chart from an image represented by the image data, and detects a change amount of magnification from a set magnification of the imaging lens from the scale value. The image reading apparatus according to any one of 1 to 6.

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