JP2006279459A - Device, method and program for image photography, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform color calibration without imposing on a user complicated operation. <P>SOLUTION: A digital camera 101 has a photography part 211 which photographs an image of a subject and outputs photographed image data, and a calibration part 221. The calibration part 221 includes a patch part which photographs a color patch provided in the device by using external light at the time of the photography of the image by the photography part 211 and outputs patch image data, and a calibration part which performs color calibration of the photographed image data obtained by the photography part 211 based upon the patch image data generated by the patch part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image capturing device for capturing an image, an image capturing method, an image capturing program, and a recording medium.

  Conventionally, in photography, regardless of silver salt type or digital type, the color of the reproduced image may differ depending on the device characteristics of each camera and the photographing conditions such as illumination. In order to prevent such variations in the reproduced image, color calibration is performed. As a general method of color calibration, there is a method using patch photography. When performing color calibration by patch shooting, color patches are shot under a shooting light source, the ideal values of each color are compared with the output values of each color obtained by shooting, and calibration is performed so that they are close to the ideal values ( For example, see Patent Documents 1 and 2 below.)

JP 2002-31014 A JP 2004-072769 A

  However, according to the prior art according to Patent Document 1, the user has to perform patch photographing. For this reason, when taking a picture, the color patch must be carried, and there is a problem that it is complicated. Further, in patch shooting, there is a problem that it is necessary to shoot under appropriate conditions with respect to the shooting light source, and skill is required.

  The prior art according to Patent Document 2 uses patch data obtained from a known chart, and does not require patch shooting by the user himself. However, the correction value obtained is an approximate value, and there is a problem in that correction under a photographing light source cannot be performed strictly.

  In order to solve the above-described problems caused by the conventional technology, the present invention can perform color calibration (color calibration) using a color patch without burdening the user with complicated operations, an image capturing method, and an image capturing method. An object is to provide a photographing program and a recording medium.

  In order to solve the above-described problems and achieve the object, an image capturing apparatus according to the present invention captures an image of a subject, outputs captured image data, and captures an image by the image capturing unit. The image capturing is performed based on the patch image data captured by the patch image capturing unit that captures the color patch provided in the apparatus using the external light and outputs the patch image data. Calibrating means for performing color calibration of the photographed image data photographed by the means.

  In this case, a color patch is provided inside the image photographing apparatus, patch photographing is performed, and the photographed image data is calibrated based on the patch image data. Accordingly, it is possible to provide photographed image data that has been subjected to color calibration (color calibration) using a color patch without burdening the user with complicated operations.

  Further, the calibration means may calibrate the RGB values of the photographed image data based on the RGB values of the patch image data photographed by the patch photographing means and the reference RGB values of the color patches. .

  In this case, the captured image data can be calibrated according to the reference RGB value of the color patch.

  Further, the color patch may be gray or an array of reference colors.

  In this case, the color patches provided in the image photographing apparatus need only be gray or those in which the respective reference colors are arranged, and the space in the apparatus can be used effectively.

  The color patch may be white, the patch photographing unit may photograph the white color patch, and the calibration unit may calibrate the white balance of the photographed image data.

  In this case, the color patch provided in the image photographing apparatus may be only white, and the space in the apparatus can be used effectively. Also, it is possible to provide photographed image data calibrated to white balance suitable for the external light at the time of image photographing.

  In addition, setting means for setting a white balance under the external light, the calibration means, based on the white balance under the external light set by the setting means and the patch image data, Color proofing may be performed.

  In this case, set a white balance under a predetermined external light such as sunset or fluorescent light, and perform color calibration based on the set white balance and a white balance that is suitable for the external light at the time of image shooting. Applicable captured image data can be provided.

  In addition, the patch photographing unit includes an obtaining unit that obtains the external light, and the determination to determine whether the external light obtained by the obtaining unit is a light amount that can be taken by the patch photographing unit. Means may be provided.

  In this case, it is determined whether a sufficient amount of light for capturing the color patch can be acquired. For this reason, it is possible to prevent the shooting of the color patch from failing due to insufficient light quantity.

  In addition, an image photographing method according to the present invention is provided in an apparatus using an image photographing process for photographing an image of a subject and outputting photographed image data, and external light when the image is photographed by the image photographing process. A color image of the captured image data captured by the image capturing process based on the patch image data captured by the patch capturing process and the patch capturing process of capturing the color patch and outputting the patch image data And a calibration process for performing calibration.

  In this case, a color patch is provided inside the apparatus, patch shooting is performed, and the captured image data is calibrated based on the patch image data. Accordingly, it is possible to provide photographed image data that has been subjected to color calibration (color calibration) using a color patch without burdening the user with complicated operations.

  An image capturing program according to the present invention causes a computer to execute the above-described image capturing method.

  In this case, a color patch is provided inside the apparatus, patch shooting is performed, and the captured image data is calibrated based on the patch image data. Accordingly, it is possible to provide photographed image data that has been subjected to color calibration (color calibration) using a color patch without burdening the user with complicated operations.

  Further, the above-described image photographing program may be recorded on a computer-readable recording medium.

  Exemplary embodiments of an image capturing device, an image capturing method, an image capturing program, and a recording medium according to the present invention will be described below in detail with reference to the accompanying drawings.

(Embodiment)
FIG. 1 is a diagram illustrating an example of a usage mode of the image capturing apparatus according to the embodiment. The image capturing apparatus according to the embodiment is realized by the digital camera 101. The digital camera 101 converts an image into an electrical signal using a semiconductor element (optical element) that reacts to light, such as a CCD or CMOS, and outputs the image data. The digital camera 101 receives light from the light source 102 and captures light reflected by the subject 103 with an optical element.

  When performing normal patch photography, a color patch (not shown) is placed under the light of the light source 102 together with the subject 103 and photographed by the digital camera 101. Then, the RGB value (output RGB value) of the captured image data is compared with the RGB value (ideal RGB value) of the color patch to be originally expressed, and calibration is performed so that the output RGB value approaches the ideal RGB value. Do it.

  In the present embodiment, the color patch is provided inside the digital camera 101. The digital camera 101 acquires light from the light source 102 from the daylighting window 101a and performs patch photography. For this reason, the user does not need to carry a color patch, and the user does not need to perform patch photographing and calibration by himself / herself.

(Functional configuration of digital camera 101)
FIG. 2 is a block diagram illustrating a functional configuration of the digital camera. The digital camera 101 includes a control unit 201, an imaging unit 211, an operation unit 212, a display unit 213, an image processing unit 214, an image recording unit 215, and a calibration unit 221. The control unit 201 performs control processing for the entire digital camera 101.

  The imaging unit 211 includes a lens and an optical element, generates image data from light incident from the lens, and outputs it as digital data. At this time, the data output from the imaging unit 211 is RAW data, which is an electric signal obtained from the optical element and digitized as it is.

  The operation unit 212 includes operation buttons, a touch panel, and the like, and is used for operation of the digital camera 101 by a user. Items operated by the operation unit 212 include, for example, setting of a shooting mode, viewing / deleting a shot image, shooting timing (shutter), output data format, and the like. The operation unit 212 may be provided integrally with the digital camera 101, or may be configured to be operated separately from the digital camera 101 like a remote controller. Also, the operation unit 212 performs an operation for shifting to a white balance adjustment mode, which will be described later.

  The display unit 213 is configured by a liquid crystal display or the like, and includes image data captured by the digital camera 101, thumbnails of image data recorded in an image recording unit 215 described later, a device setting menu screen of the digital camera 101, an operation error message, and the like. Is displayed. Information displayed on the display unit 213 can be operated by the operation unit 212.

  The image processing unit 214 performs image processing on the image data output from the photographing unit 211. Image processing performed by the image processing unit 214 includes color processing, gradation processing, edge processing, and the like according to the shooting mode set by the operation unit 212 and the format of output data.

  The image recording unit 215 records the image data processed by the image processing unit 214. The image recording unit 215 may be a recording medium that can be attached to and detached from the digital camera 101, such as a memory card, in addition to being provided integrally with the digital camera 101. With such a configuration, image data can be exchanged with a PC or printer (not shown) without using a cable or the like. In addition, both a device provided integrally with the digital camera 101 and a device removable from the digital camera 101 may be provided.

  For example, JPEG data or RAW data can be selected as the format of image data (hereinafter referred to as output data format) written to the memory card by the image recording unit 215. As described above, the image data output from the photographing unit 211 is RAW data. However, when JPEG data is selected as the output data format, the image processing unit 214 performs image processing and converts it into JPEG data. . Further, the image processing unit 214 may add a tag and a thumbnail to the JPEG file and output the file as an Exif file.

  The Exif file output by the image recording unit 215 is obtained by adding a tag and a thumbnail to JPEG data (hereinafter referred to as “main data”) of a captured image, and consideration is given to mutual use of image data among a plurality of devices. The tag records image data attribute information such as the number of pixels of the image, compression mode, camera model name, aperture value, shutter speed, and shooting date and time. Using this information, the user can further utilize the image data, such as feeding back the exposure condition at the time of shooting to the shooting, or referring to image selection at the time of printing.

  The thumbnail is a reduced image for list heading obtained by reducing this data, and is used to display a list of image files at high speed on the display unit 213 or the image processing application of the PC.

  The calibration unit 221 performs color calibration of the digital camera 101 by patch shooting. Hereinafter, description will be made assuming that the calibration unit 221 calculates a white balance calibration value. Here, the white balance is to adjust the color reproduction of the image data in accordance with the light of the light source 102 applied to the subject 103 so that white can be expressed as white.

  For white balance adjustment, in addition to calibration by patch shooting, for example, the color of the illumination light is expressed by the color temperature (K), and the RGB value balance can be adjusted accordingly, or the shooting mode can be adjusted in advance according to the shooting scene. And the user can select a shooting mode according to the shooting scene. However, since such a method is not a value adjusted under the actual light source 102, a strict calibration cannot be performed. For this reason, the digital camera 101 incorporates a color patch therein, performs patch shooting based on the light source 102 at the time of shooting, and adjusts the white balance. Thereby, it is possible to provide a reproduction image that is more realistic.

  FIG. 3 is a block diagram illustrating a functional configuration of the calibration unit. The calibration unit 221 includes a photographing light source acquisition unit 301, a patch unit 302, a calibration unit 303, a light amount detection unit 304, and a light amount determination unit 305. The shooting light source acquisition unit 301 acquires the light of the light source 102 when taking a picture with the digital camera 101 from the lighting window 101 a and guides it to the patch unit 302.

  The patch unit 302 includes a color patch for calibration, performs color patch shooting (patch shooting) with the light acquired by the light source acquisition unit 301 during shooting, and outputs RGB values obtained by shooting to the calibration unit 303. To do. When the color calibration performed by the calibration unit 221 is only white balance adjustment, the patch may be only a white patch.

  The calibration unit 303 compares the RGB value at the time of patch shooting output from the patch unit 302 with the ideal RGB value of the color, and calculates the calibration value of the RGB value. Further, the calibration unit 303 calibrates the RGB values of the image data based on the calculated calibration values of the RGB values. Since various algorithms are known for the calibration value calculation method, a detailed description thereof will be omitted.

  The light amount detection unit 304 detects the light amount of light acquired by the photographing light source acquisition unit 301. The light amount determination unit 305 determines whether the light amount detected by the light amount detection unit 304 is sufficient for the patch unit 302 to take a patch image. If sufficient light is not supplied to the patch unit 302, such as when the daylighting window 101a is covered with a shadow, the RGB values output by patch shooting differ from those under the light source during shooting, and the correct white balance This is because it cannot be calibrated.

  With the configuration described above, the digital camera 101 calibrates the captured image and provides an appropriate reproduced image. Image calibration is performed by calculating a calibration value and applying the calibration value to a captured image. Hereinafter, a calibration value calculation process performed by the digital camera 101 and a process at the time of taking a picture will be described.

(Digital camera 101 calibration process)
FIG. 4 is a flowchart showing a procedure of calibration value calculation processing performed by the digital camera. First, the control unit 201 determines whether a white balance adjustment mode is designated (step S401). The white balance adjustment mode is designated by operating the operation unit 212 by the user, for example. When the white balance adjustment mode is designated (step S401: Yes), the shooting light source acquisition unit 301 acquires the light of the shooting light source (step S402). On the other hand, if the white balance adjustment mode cannot be designated, the process waits until the designation is made (step S401: No loop).

  In step S402, when the light from the light source during photographing is acquired, the light amount detection unit 304 detects the light amount of the acquired light (step S403). Then, the light amount determination unit 305 determines whether a sufficient amount of light is secured for performing patch photography (step S404). If a sufficient amount of light is secured (step S404: Yes), patch shooting is performed by the patch unit 302 (step S405).

  On the other hand, when a sufficient light quantity is not secured (step S404: No), an error message is displayed on the display unit 213 (step S406), and the process returns to S404 and waits until a sufficient light quantity is secured. This error message is an indication that correct calibration cannot be performed because sufficient light quantity is not secured for performing patch photography.

  When patch shooting is performed in step S405, the calibration unit 303 compares the patch shooting data output by the patch unit 302 with the reference RGB value (step S407), and calculates the calibration value of the RGB value (step S407). S408), the process according to this flowchart is terminated. Here, the reference RGB value is an RGB value indicating each color in each color space.

  FIG. 5 is a flowchart showing a processing procedure of the digital camera at the time of photographing. When the user performs an operation for taking a photograph and acquires image data (step S501), the control unit 201 determines whether the user has set a shooting mode (step S502). In the shooting mode, an appropriate white balance is set by applying a preset RGB value suitable for a specific light source such as sunset, night view, or fluorescent lamp.

  When the shooting mode is set (step S502: Yes), the calibration unit 303 performs a calibration process in which the calibration value is reflected in the RGB value of the shooting mode on the image data acquired in step S501 (step S503). ), The process proceeds to step S505. On the other hand, when the shooting mode is not set (step S502: No), the image data acquired in step S501 is calibrated according to the calibration value (step S504). Then, the image data after the calibration process is stored in the image recording unit 215 (step S505).

  When the user's operation is finished and shooting is finished (step S506: Yes), the processing according to this flowchart is finished. On the other hand, when the photographing is not completed (step S506: No), the process returns to step S501 and the subsequent processing is repeated.

  As described above, according to the image photographing apparatus according to the present embodiment, a color patch is provided in the image photographing apparatus, patch photographing is performed, and the photographed image data is calibrated based on the patch image data. Accordingly, it is possible to provide photographed image data that has been subjected to color calibration (color calibration) using a color patch without burdening the user with complicated operations.

  Further, by providing only the white color patch, it is possible to adjust the white balance while effectively utilizing the space in the apparatus. In addition, color calibration is performed based on the set white balance and the white balance suitable for the external light at the time of image capture depending on the shooting mode, and the captured image data more suitable for reality can be provided.

  By providing the light amount determination unit 305, it is determined whether a sufficient amount of light for capturing the color patch can be acquired. For this reason, it is possible to prevent the shooting of the color patch from failing due to insufficient light quantity.

  The image capturing method described in the present embodiment can be realized by executing a program prepared in advance on a computer such as a personal computer or a workstation. This program is recorded on a computer-readable recording medium such as a hard disk, a flexible disk, a CD-ROM, an MO, and a DVD, and is executed by being read from the recording medium by the computer. The program may be a transmission medium that can be distributed via a network such as the Internet.

The figure which shows an example of the usage condition of the imaging device concerning embodiment. The block diagram which shows the functional structure of a digital camera. The block diagram which shows the functional structure of a calibration part. The flowchart which shows the procedure of the calibration value calculation process which a digital camera performs. The flowchart which shows the process sequence of the digital camera at the time of photography.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 Digital camera, 101a Daylighting window, 102 Light source, 103 Subject, 201 Control part, 211 Photographing part, 212 Operation part, 213 Display part, 214 Image processing part, 215 Image recording part, 221 Calibration part, 301 Acquisition of light source during photographing Section 302 patch section 303 calibration section 304 light quantity detection section 305 light quantity determination section

Claims (9)

Image capturing means for capturing an image of a subject and outputting captured image data;
A patch photographing means for photographing a color patch provided in the apparatus using external light when photographing an image by the image photographing means, and outputting patch image data;
A calibration unit that performs color calibration of the captured image data captured by the image capturing unit based on the patch image data captured by the patch capturing unit;
An image photographing apparatus comprising:   The calibration means calibrates the RGB values of the photographed image data based on the RGB values of the patch image data photographed by the patch photographing means and a reference RGB value of the color patch. Item 2. The image photographing device according to Item 1.   The image photographing apparatus according to claim 1, wherein the color patch is a gray color or an array of reference colors. The color patch is white;
The patch photographing means photographs the white color patch,
3. The image photographing apparatus according to claim 1, wherein the calibration unit calibrates white balance of the photographed image data. Setting means for setting the white balance under the external light,
5. The image photographing apparatus according to claim 4, wherein the calibration unit performs the color calibration based on the white balance under the external light set by the setting unit and the patch image data. . The patch photographing means includes an acquisition means for acquiring the external light,
6. The apparatus according to claim 1, further comprising a determination unit configured to determine whether the external light acquired by the acquisition unit is an amount of light that can be captured by the color patch performed by the patch imaging unit. The image photographing device described. An image capturing process for capturing an image of a subject and outputting captured image data;
A patch photographing step of photographing a color patch provided in the apparatus using outside light when photographing an image by the image photographing step, and outputting patch image data;
Based on the patch image data photographed by the patch photographing process, a calibration process for performing color calibration of the photographed image data photographed by the image photographing process;
An image photographing method comprising:   An image photographing program for causing a computer to execute the image photographing method according to claim 7. A computer-readable recording medium on which the image photographing program according to claim 8 is recorded.

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