JP5211926B2 - Digital camera, image processing apparatus, and image processing program - Google Patents

Description

  The present invention relates to a white balance processing technique.

A general digital camera performs white balance adjustment on Raw format data at the time of shooting. This white balance adjustment is a process of adjusting so that an achromatic subject is photographed as an achromatic image regardless of the characteristics of ambient light. White balance adjustment methods used in digital cameras include manual white balance method, preset white balance method, and auto white balance method. Auto white balance method is especially widely used because it does not burden the user with the operation. ing. However, the auto white balance method is not always perfect, and color fog may occur in the entire captured image. In view of this, a technique is disclosed in which application software is used to designate an achromatic region of an image after shooting and white balance adjustment is performed on the designated achromatic region (see, for example, Patent Document 1).
JP 2008-067298 A

  However, in the prior art, white balance adjustment must be performed using application software after shooting, and a device such as a personal computer on which application software operates must be prepared. Even if the same software can be installed in the camera, it is necessary to designate an achromatic region on a small screen mounted on the digital camera, which requires a complicated operation.

  An object of the present invention is to provide a digital camera, an image processing apparatus, and an image processing program capable of performing accurate white balance adjustment without performing complicated modification.

  The digital camera according to the present invention performs imaging processing by converting subject light into an electrical signal to generate image data, and applying white balance parameters to the image data generated by the imaging device to perform white balance adjustment. A digital camera including a white balance adjustment unit; a correction instruction unit that applies a first white balance parameter to the image data generated by the imaging unit to instruct whether to execute a white balance correction after the white balance adjustment; When the correction instruction means instructs execution of white balance correction, the image pickup means captures an achromatic image and generates reference image data, and the reference image data is a second white from the reference image data. The second white bar for determining the balance parameter Characterized by providing a Nsu parameter acquisition means.

  Preferably, the image buffer temporarily stores image data captured by the imaging unit, and the image data stored in the image buffer when execution of white balance correction is instructed by the correction instruction unit. The image processing apparatus further includes a modified image data acquisition unit that applies the second white balance parameter to perform white balance adjustment and acquires final image data.

  Preferably, the image buffer temporarily stores a plurality of pieces of image data captured by the imaging unit, and the corrected image data acquisition unit includes the second white balance parameter among the plurality of pieces of image data. The white balance adjustment is performed by applying the second white balance parameter of the image data to which the second white balance parameter is not applied among the plurality of pieces of image data. .

  Preferably, the second white balance parameter obtained by the second white balance parameter acquisition unit and the image data before white balance adjustment photographed by the imaging unit are recorded in association with each other on a storage medium. Is further provided.

  Preferably, the recording unit stores the first white balance parameter in the storage medium as tag information of image data before white balance adjustment, and the second white balance parameter acquisition unit stores the second white balance parameter. After the gain is calculated, the second white balance parameter is stored in place of the first white balance parameter stored as the tag information.

  Preferably, the white balance adjustment unit further includes a display unit that applies the first white balance parameter to display image data after white balance adjustment as an image on the screen, and the correction instruction unit performs white balance correction. Message information for confirming whether or not to execute is displayed on the screen of the display means.

  Preferably, the image data before white balance adjustment is Raw format image data, and the image data after white balance adjustment is Jpeg format image data.

  An image processing apparatus according to the present invention includes: an image input unit that inputs image data; and a white balance adjustment unit that executes a white balance adjustment by applying a predetermined white balance parameter to the image data input by the image input unit. A correction instructing unit for instructing whether or not to perform white balance correction after applying the first white balance parameter to the image data input by the image input unit and adjusting the white balance; Reference image input means for inputting reference image data of an achromatic image when the execution of white balance correction is instructed by the means, and second white balance parameter acquisition means for obtaining a second white balance parameter from the reference image data; With the feature That.

  An image processing program according to the present invention is an image processing program executed using a computer, and an image input procedure for inputting image data and a predetermined white balance parameter applied to the image data input in the image input procedure A white balance adjustment procedure for executing white balance adjustment, and instructing whether or not to execute white balance correction after the white balance adjustment by applying the first white balance parameter to the image data input in the image input procedure. A correction instruction procedure, a reference image input procedure for inputting reference image data of an achromatic color image when execution of white balance correction is instructed by the correction instruction procedure, and a second white balance parameter is obtained from the reference image data 2nd white balance para Characterized by providing a chromatography data acquisition procedure.

  In the present invention, when the execution of white balance correction is instructed for a captured image, the second white balance parameter is obtained by performing the reference photographing, so that an accurate white can be obtained without performing complicated conversion. Balance adjustment can be performed.

  Hereinafter, embodiments of a digital camera as an example of a digital camera, an image processing apparatus, and an image processing program according to the present invention will be described.

(First embodiment)
The digital camera 101 according to the first embodiment will be described in detail with reference to the drawings.
[Overall Configuration of Digital Camera 101]
FIG. 1 is a block diagram illustrating a configuration of a digital camera 101 according to the present embodiment. The digital camera 101 includes a photographing optical system 102, a mechanical shutter 103, an image sensor 104, an AFE (analog front end) 105, an A / D conversion unit 106, an image buffer 107, a control unit 108, and a memory 109. And a display unit 110, a memory card I / F 111, and an operation unit 112.

  In FIG. 1, the subject light incident on the photographing optical system 102 is incident on the light receiving surface of the image sensor 104 via the mechanical shutter 103. Here, the photographing optical system 102 includes a plurality of lenses such as a zoom lens and a focus lens, and has a diaphragm 102a.

  A photoelectric conversion unit is two-dimensionally arranged on the light receiving surface of the image sensor 104, and is converted into an electrical signal according to the amount of light incident on each photoelectric conversion unit and output to the AFE 105.

  The AFE 105 performs noise removal and amplification of the electrical signal output from the image sensor 104 and outputs the result to the A / D converter 106.

  The A / D conversion unit 106 converts the electrical signal output from the AFE 105 into a digital signal, and temporarily stores the digital signal for one screen in the image buffer 107 as Raw format image data (Raw data). The raw data is raw image data that has not been processed and is read out from the image sensor 104 and is composed of pixel data of a Bayer array that constitutes the image sensor 104. The image buffer 107 can temporarily hold a plurality of Raw data images.

  The control unit 108 performs color interpolation processing (processing for converting Bayer array data into RGB format image data in units of pixels (debayer processing)) or white for the image data temporarily stored in the image buffer 107. Balance processing, matrix processing (matrix operation processing for color correction such as saturation), gamma characteristic conversion processing, YCrCb processing (processing for converting RGB format image data into luminance / color difference format image data), Jpeg compression processing, etc. The image processing is executed. Note that Jpeg-format image data after Jpeg compression is stored as a Jpeg image file in the memory card 111a connected via the memory card I / F 111. In the present embodiment, the control unit 108 also saves RAW data temporarily stored in the image buffer 107 in the memory card 111a. In particular, when saving Raw data, an image file in which white balance gain used for white balance adjustment is added to Raw data as tag information is formed and saved in the memory card 111a. The white balance gain and tag information will be described in detail later.

  Here, the JPEG image file saved in the memory card 111a and the Raw data image file (Raw image file) are given file names that differ only in attributes, and the Raw image file from the JPEG image file is reversed. A Jpeg image file can be searched and read from the image file. For example, when the file name of the Jpeg image file is “aaa.jpg”, the corresponding file name of the Raw image file is stored as “aaa.raw”.

  The memory 109 stores the shooting mode, exposure information, focus information, and the like of the digital camera 101. In addition, the memory 109 displays an image of Raw data temporarily stored in the image buffer 107 and an image stored as a JPEG image file or a Raw image file on the memory card 111 a connected to the memory card IF 111. When displaying on the unit 110, it is also used as a display buffer that temporarily stores the pixel number and format corresponding to the display unit 110 after conversion.

  The display unit 110 includes a liquid crystal monitor that displays an image, a menu screen, and the like in response to a command from the control unit 108.

As shown in the external view of the digital camera 101 in FIG. 2, the operation unit 112 includes a power button 201, a release button 202, a zoom button 203, a cross key 204 (up key 204a, down key 204b, left key 204c, and right key 204d. ) And various operation buttons such as a confirmation button 205. The user operates the digital camera 101 by operating these operation buttons. The operation information of these operation buttons is output to the control unit 108, and the control unit 108 controls the entire operation of the digital camera 101 according to the operation information input from the operation unit 112. Further, the operation unit 112 selects the menu item 206, the menu item 207, the YES button 208, the NO button 209, etc. displayed on the screen of the display unit 110 in FIG. Confirm the selection. For example, each time the upper key 204a or the lower key 204b of the cross key 204 is pressed, the four selection objects of the menu item 206, the menu item 207, the YES button 208, and the NO button 209 are sequentially selected, and the selected item or button is selected. Is displayed with a thick frame. In the case of FIG. 2, the menu item 207 is selected with the cross key 204, and the menu item 207 is displayed surrounded by a thick frame indicating that it is selected. In the case of the YES button 208 and the NO button 209 as well, when the cross key 204 is selected in order, each selected button is displayed with a thick frame. When the confirm button 205 is pressed while the menu item or button is displayed in a thick frame in this way, the selection of the menu item or button displayed in the thick frame is confirmed.
[Configuration of Control Unit 108]
Next, the configuration of the control unit 108 in FIG. 1 will be described in detail. The control unit 108 operates according to a program stored therein in advance, and controls each unit of the digital camera 101. The control unit 108 includes a lens control unit 121, an aperture control unit 122, a shutter control unit 123, an AF (automatic focus) control unit 124, an AE (automatic exposure) control unit 125, and a WB (white balance) control unit. 126 or the like. In this embodiment, the lens control unit 121, the aperture control unit 122, the shutter control unit 123, the AF control unit 124, the AE control unit 125, and the WB control unit 126 are included in the control unit 108 so that the explanation is easy to understand. Although depicted, it may be configured by a circuit or block different from the control unit 108.

  For example, the control unit 108 moves the position of the zoom lens of the photographing optical system 102 via the lens control unit 121 according to the operation of the zoom button 203 of the operation unit 112. Similarly, the control unit 108 adjusts the aperture value of the aperture 102 a of the photographing optical system 102 via the aperture control unit 122. Further, the control unit 108 opens and closes the mechanical shutter 103 via the shutter control unit 123 according to the shutter speed.

  The AF control unit 124 calculates a defocus amount by a focus detection method such as a hill-climbing method at a predetermined position (AF measurement position) of the image captured in the image buffer 107 to obtain a focus position. The control unit 108 adjusts the position of the focus lens of the photographing optical system 102 via the lens control unit 121 so that the focal position obtained by the AF control unit 124 is obtained. The predetermined position of the image on which the focus control is performed is a position where the focus control is set in advance such as the center of the screen. In particular, in the present embodiment, the position of the achromatic portion in the case of performing reference photographing with white balance adjustment is also used as the AF measurement position (AF area). Reference shooting will be described in detail later.

  The AE control unit 125 performs photometry at a predetermined position (AE photometry position) of the image taken into the image buffer 107. The control unit 108 determines the aperture value of the aperture 102a, the shutter speed of the mechanical shutter 103, and the like so as to achieve appropriate exposure according to the photometric value obtained by the AE control unit 125, and the aperture control unit 122 and the shutter control unit. 123. The predetermined position of the image for which exposure control is performed is set to a preset position such as the center of the screen, for example, in the same manner as the predetermined position of the image for which focus control is performed. In this embodiment, the mechanical shutter 103 is used. However, an electronic shutter that controls the shutter speed according to the exposure time of the image sensor 104 by opening the mechanical shutter 103 may be used. In particular, when the preview image is taken, the mechanical shutter 103 is always open. Here, the preview image is used for displaying a moving image continuously captured in time by the image sensor 104 on the display unit 110 and determining a shooting composition and the like.

  The WB control unit 126 performs white balance adjustment on the Raw data temporarily captured in the image buffer 107 described above. The white balance adjustment is a process for adjusting an achromatic subject to finally become an achromatic image regardless of the characteristics of ambient light. In general, when the characteristics (for example, color temperature) of ambient light (such as sunlight, incandescent light, and fluorescent light) change for an achromatic subject, the subject is achromatic when viewed under that ambient light. Although it can be recognized, the raw data captured by the camera changes according to the characteristics of the ambient light, so even if the ambient light changes, it is necessary to adjust the white balance so that the achromatic subject will be an achromatic image. is there.

  This white balance adjustment is realized, for example, by multiplying Raw data by gain values (gainR, gainB) set according to the R and B channels. For example, the average value of the Raw data obtained by photographing an achromatic subject is calculated for each of the R, G, and B channels. The calculation results are Ra, Ga, and Ba, respectively. GainR and gainB can be obtained as in (Expression 1) and (Expression 2).

gainR = Ga / Ra (Formula 1)
gainB = Ga / Ba (Formula 2)
In this way, the white balance gain can be obtained from the image data of the achromatic object, but there are the following three methods for obtaining the white balance adjustment parameters such as the white balance gain. Three schemes can be selected.
(Manual white balance method) A method in which the user of the digital camera 101 inputs ambient light information and selects ambient light, and obtains white balance adjustment parameters from the information.
(Preset white balance method) A method in which a user shoots an achromatic object such as a gray plate before the main shooting and obtains white balance adjustment parameters from the captured achromatic image data.
(Auto white balance method) A method in which the digital camera automatically calculates parameters for white balance adjustment without any user operation.

  Among the three methods described above, the auto white balance method is widely used because there is no burden of operation on the user. While the auto white balance method does not burden the user with the operation, it is necessary to perform an ambient light estimation process, and the estimation process is not always perfect. For example, the white balance gain calculated by the estimation process is not necessarily a white balance gain reflecting actual ambient light, and as a result, a color cast such as magenta or yellow may occur in the entire captured image. For example, an image photographed by the auto white balance method may be photographed green under a fluorescent lamp such as day white, or reddish under an incandescent lamp.

The digital camera 101 according to the present embodiment can correct the white balance adjustment parameters after taking an image using the auto white balance method or the like.
[Configuration of WB Control Unit 126]
Next, the configuration of the WB control unit 126 in FIG. 1 will be described in detail with reference to FIG. In FIG. 3, the WB control unit 126 includes a first WB gain setting unit 141, a second WB gain setting unit 142, a switching unit 143, a WB conversion unit 144, a WB correction control unit 145, a data creation unit 146, And a color interpolation processing unit (Debayer processing unit) 147.

  In FIG. 3, an imaging unit 131 is a block in which the imaging optical system 102, the mechanical shutter 103, the imaging element 104, the AFE 105, and the A / D conversion unit 106 in FIG. 1 are collected. The correction processing unit 132 is a block that performs matrix processing (color correction processing such as saturation) and gamma characteristic conversion processing on the image data after white balance adjustment. The Jpeg compression unit 133 is a block that performs image compression processing according to the Jpeg standard on the RGB format image data output from the correction processing unit 132, and creates Jpeg format image data. The Jpeg image data created by the Jpeg compression unit 133 is stored in the memory card 111a via the memory card I / F 111 as a Jpeg image file to which information such as a file name and creation date / time is added.

  In FIG. 3, the digital camera 101 according to the present embodiment captures the actual captured image and the reference image for white balance correction with the imaging unit 131 and temporarily stores the captured image in the image buffer 107. Next, the raw data of the captured image temporarily stored in the image buffer 107 is subjected to debayer processing by the color interpolation processing unit 147, and then input to the WB conversion unit 144, and the white data input from the switching unit 143. White balance conversion is performed using the balance gain. When there is no white balance correction instruction from the WB correction control unit 145, the switching unit 143 outputs the white balance gain set in the first WB gain setting unit 141 to the WB conversion unit 144, and the WB correction control unit When there is a white balance correction instruction from 145, the white balance gain set in the second WB gain setting unit 142 is output to the WB conversion unit 144. The user operates various operation buttons of the operation unit 112 to instruct the WB correction control unit 145 to execute white balance correction. Receiving this, the WB correction control unit 145 controls the imaging unit 131, the second WB gain setting unit 142, the switching unit 143, and the data creation unit 146, and corrects the white balance.

  In normal shooting, the WB conversion unit 144 performs white balance conversion using the white balance gain set in the first WB gain setting unit 141, and outputs the image data after WB to the correction processing unit 132. Here, the white balance gain set in the first WB gain setting unit 141 differs depending on the white balance mode set by the user in the digital camera 101. For example, when the white balance mode is the manual white balance method, the white balance gain calculated in accordance with the selection of the ambient light information and the ambient light set by the user before shooting is set in the first WB gain setting unit 141. . Alternatively, when the white balance mode is the preset white balance method, the user takes an achromatic object such as a gray plate before photographing, and the white balance gain calculated from the photographed achromatic image data is the first WB gain. It is set in the setting unit 141. When the white balance mode is the auto white balance method, the raw data of the captured image stored in the image buffer 107 in FIG. 3 is input, and the first WB gain setting unit 141 estimates the color temperature and ambient light. The white balance gain that seems to be optimal is automatically calculated according to a predetermined algorithm. The first WB gain setting unit 141 sets the obtained white balance gain as a white balance gain to be output to the WB conversion unit 144.

  On the other hand, the data creation unit 146 creates a Raw data image file (Raw image file) by combining the Raw data temporarily stored in the image buffer 107 and the white balance gain output from the switching unit 143. In particular, at this time, the data creation unit 146 adds the white balance gain output from the switching unit 143 to the raw image file as tag information of the raw image file. For example, the first white balance gain set in the first WB gain setting unit 141 is added as tag information of the raw image file of the actual captured image and temporarily stored in the memory card 111a, and then the WB correction control unit 145 When the white balance is corrected, the tag information of the RAW image file of the actual captured image stored in the memory card 111a is set to the second white set in the second WB gain setting unit 142 from the first white balance gain. Instead of the balance gain, it is stored again in the memory card 111a.

  An example of the Raw image file is shown in FIG. In FIG. 4, a header describes information such as a file name and a shooting date and time, and subsequently, Raw data and white balance gain are stored to form one Raw image file. In this way, since the raw data and the white balance gain are stored in association with each other, when the raw image file is later read and displayed on a personal computer or the like, the white balance gain stored in association with the raw data is read out. Thus, white balance conversion can be performed, and an image of Raw data can be displayed with an appropriate hue. Although the white balance gain is used here, the gain is not necessarily a gain value, and any white balance adjustment parameter may be used.

  In this way, in normal shooting, the WB conversion unit 144 performs white balance conversion using the white balance gain set in the first WB gain setting unit 141. Then, the image data after the white balance conversion by the WB conversion unit 144 is subjected to the matrix processing and the gamma characteristic conversion processing described above by the correction processing unit 132, and then subjected to Jpeg compression by the Jpeg compression unit 133 to perform the main photographing. The image is saved in the memory card 111a as a JPEG image file. At the same time, the actual captured image stored in the memory card 111 a is displayed on the display unit 110 of the digital camera 101.

  As described above, in normal shooting, the WB conversion unit 144 performs white balance conversion using the white balance gain set in the first WB gain setting unit 141. White balance adjustment is performed according to the white balance mode. For this reason, when the white balance mode set in the digital camera 101 is the auto white balance mode or the manual white balance mode, the white balance of the photographed image displayed on the display unit 110 after photographing may be shifted. . However, with a conventional digital camera, it is difficult to re-adjust the white balance in the digital camera after shooting, and the post-shooting raw image file stored in the memory card 111a is read by the image processing application software on the personal computer to adjust the white balance. I had to start over. For example, it is necessary to display a captured image on a PC screen, and the user specifies an achromatic region in the captured image, obtains a white balance gain in that region, and performs white balance conversion using the obtained white balance gain. There is. On the other hand, in the digital camera 101 according to the present embodiment, the user can check the captured image displayed on the display unit 110 and can perform white balance correction as necessary after shooting. .

  In this embodiment, when the user looks at the captured image displayed on the display unit 110 of the digital camera 101 after shooting and feels that the white balance is shifted, the user presses the operation button of the operation unit 112 in FIG. The white balance correction instruction is given to the WB correction control unit 145 by operating. Receiving this, the WB correction control unit 145 displays a menu for selecting a white balance method (reference image shooting, color temperature setting, light source type setting, etc.) on the display unit 110. Further, when the user selects to capture the reference image, message information is displayed to the user to capture an achromatic subject. When the user captures an achromatic object and presses the release button 202, a reference image is taken by the imaging unit 131 and temporarily stored in the image buffer 107. Then, the second WB gain setting unit 142 obtains the white balance gain from the reference image temporarily stored in the image buffer 107 as described above using (Equation 1) and (Equation 2), and performs switching. To the unit 143. Since the switching unit 143 switches to output the white balance gain of the second WB gain setting unit 142 to the WB conversion unit 144 according to an instruction from the WB correction control unit 145, the WB conversion unit 144 stores in the image buffer 107. The white balance conversion is performed on the image data of the actual captured image using the white balance gain of the second WB gain setting unit 142.

In this way, the user can correct the white balance after shooting if the user sees the actual captured image displayed on the display unit 110 and feels that the white balance has shifted. Note that the image data after white balance correction output from the WB conversion unit 144 is converted into a Jpeg image file via the correction processing unit 132 and the Jpeg compression unit 133 in the same manner as the above-described shooting with auto white balance. And stored in the memory card 111a. At this time, the Jpeg image file after the white balance correction is stored in place of the Jpeg image file stored in the memory card 111a in the previous auto white balance shooting. Also, the tag information of the RAW image file stored in the memory card 111a in the previous auto white balance shooting is set in the second WB gain setting unit 142 from the first white balance gain at the time of auto white balance. It is replaced with the second white balance gain and stored again in the memory card 111a.
[Example of white balance correction during shooting]
Next, a series of white balance adjustment operations in the digital camera 101 will be described in detail with reference to the flowchart of FIG. Note that the processing of the flowchart shown in FIG. 5 is started from processing in which the user depresses the release button 202 and performs main image shooting. It is assumed that the white balance mode of the digital camera 101 is set to the auto white balance mode.

  (Step S <b> 101) The user presses the release button 202 of the operation unit 112 to start photographing the main image.

  (Step S102) When the release button 202 of the operation unit 112 is pressed, the control unit 108 executes a photographing process.

  Here, a specific photographing process performed in this processing step will be described. When the release button 202 is pressed, first, the shutter control unit 123 of the control unit 108 opens and closes the mechanical shutter 103 at a shutter speed based on the exposure information obtained by the AE control unit 125. Subject light incident through the imaging optical system 102 while the mechanical shutter 103 is open is imaged on the light receiving surface of the image sensor 104 through the Bayer array RGB filter. The subject light imaged on the light receiving surface of the image sensor 104 is converted into an electrical signal in accordance with the amount of light for each pixel, and Raw data is temporarily stored in the image buffer 107 via the AFE 105 and the A / D converter. The Then, as described with reference to FIG. 3, the first WB gain setting unit 141 obtains the white balance gain by the auto white balance method based on the Raw data temporarily stored in the image buffer 107. The WB conversion unit 144 performs white balance conversion using the white balance gain. The image data subjected to white balance conversion by the WB conversion unit 144 is stored in the memory card 111a via the correction processing unit 132 and the Jpeg compression unit 133. On the other hand, the data creation unit 146 adds, as tag information, the white balance gain obtained by the first white balance gain setting unit 141 to the Raw data temporarily stored in the image buffer 107 as described in FIG. As described above, it is stored in the memory card 111a as a RAW image file.

  (Step S <b> 103) The control unit 108 executes display processing for the actual captured image. Specifically, the WB conversion unit 144 displays the image data after the white balance conversion on the display unit 110. Note that the image data displayed on the display unit 110 may be the image data after the correction processing 132, or the JPEG data stored in the memory card 111a may be converted back to the RGB data.

  Here, an example of the actual captured image displayed on the screen of the display unit 110 is shown in FIG. In FIG. 6, not only the actual captured image 251 but also a message “Do you want to correct white balance?” Is displayed on the screen of the display unit 110. Further, as shown in FIG. 6, a “YES” button 208 and a “NO” button 209 are displayed on the screen of the display unit 110.

  Note that the “YES” button 208 and the “NO” button 209 can be selected using the cross key 204 of the operation unit 112 as described with reference to FIG. 2, and the selected button is displayed in a thick frame. . Then, when the confirm button 205 is pressed in the state displayed with the thick frame, the selection of the button displayed with the thick frame is confirmed. For example, in the case of FIG. 6, since the “YES” button 208 is displayed with a thick frame, when the confirm button 205 is pressed in this state, the selection of the “YES” button 208 is confirmed. On the other hand, when the “NO” button 209 is displayed in a thick frame and the confirm button 205 is pressed, the selection of the “NO” button 209 is confirmed.

  (Step S <b> 104) As shown in FIG. 6, the user views an image processed by auto white balance and selects whether or not to perform white balance correction. Then, the control unit 108 determines the user's selection. For example, in the case of FIG. 6, the control unit 108 determines whether the “YES” button 208 is selected or the “NO” button 209 is selected. If the “YES” button 208 is selected, the process proceeds to step S105 to start white balance correction. On the contrary, if the “NO” button 209 is selected, the white balance correction is not performed, and the process proceeds to step S116 to end the series of processes. Here, the operation in which the user selects the “YES” button 208 corresponds to an operation instructing the white balance correction from the operation unit 112 to the WB correction control unit 145 in FIG.

  (Step S <b> 105) The control unit 108 displays a white balance correction method selection menu on the screen of the display unit 110. For example, as shown in FIG. 7, on the screen of the display unit 110, a “reference shooting (method by shooting a reference image)” item 301 and a “color temperature setting (method of setting color temperature value)” item 302 are displayed. , “Light source type setting (method of setting the light source type)” item 303 is displayed. The “reference shooting” item 301, the “color temperature setting” item 302, and the “light source type setting” item 303 are selected in sequence using the cross key 204 of the operation unit 112, as described with reference to FIG. The selected item frame and button are displayed with a thick frame. When the confirm button 205 is pressed in this state, the selection of items and buttons displayed in a thick frame is confirmed.

  For example, in the case of FIG. 7, the “reference shooting” item 301 is displayed with a thick frame. Therefore, when the confirm button 205 is pressed in this state, the selection of the “reference shooting” item 301 is confirmed. Similarly, when the “color temperature setting” item 302 or the “light source type setting” item 303 is selected with the cross key 204 and displayed in a thick frame and the confirm button 205 is pressed, the “color temperature” displayed in the thick frame is displayed. The selection of “setting” item 302 or “light source type setting” item 303 is confirmed.

  (Step S106) The control unit 108 determines whether or not the white balance correction method selected in step S105 is a method for capturing a reference image. For example, in the case of FIG. 7, it is determined which one of the “reference shooting” item 301, the “color temperature setting” item 302, and the “light source type setting” item 303 is selected. If the “reference shooting” item 301 is selected, the process proceeds to step S107 to perform reference shooting. Conversely, if a method other than the “reference shooting” item 301, for example, if the “color temperature setting” item 302 or the “light source type setting” item 303 is selected in FIG. 7, the process proceeds to step S115.

  (Step S <b> 107) The control unit 108 shifts to the reference image capturing mode and displays a message prompting the user to capture an achromatic image on the screen of the display unit 110. For example, as shown in FIG. 8, a message “Please shoot an achromatic image” is displayed on the screen of the display unit 110 together with the preview image 252 displayed on the display unit 110. The preview image 252 displayed on the display unit 110 displays an area frame 253 for shooting an achromatic subject. The user determines the shooting composition by moving the digital camera 101 so that the achromatic subject comes within the frame of the area frame 253. Alternatively, the zoom button 203 is operated to zoom in or zoom out so that the area frame 253 is filled with an achromatic subject. For example, in the case of the preview image 252 in FIG. 8, the area frame 253 is aligned with the achromatic wall of the house. Here, the area frame 253 may also be used as an AF area used by the AF control unit 124. Further, as shown in FIG. 8, an achromatic object may be shown in a specific area of a part of the screen, but an achromatic object may be shown on the entire screen. In this way, an achromatic subject is captured in a predetermined area in the preview image 252.

  (Step S108) When an achromatic subject is selected in step S107, the user presses the release button 202 to capture a reference image. The captured reference image is temporarily stored in the image buffer 107 as described with reference to FIG.

  (Step S109) The second WB gain setting unit 142 of the WB control unit 126 converts the RGB image data of the portion corresponding to the area frame 253 of FIG. 8 from the Raw data of the reference image temporarily stored in the image buffer 107. Extract.

  (Step S110) The second WB gain setting unit 142 of the WB control unit 126 calculates the average value of the image data of the achromatic subject area extracted in Step S109 for each of the R, G, and B channels. For example, the average values calculated for each of the R, G, and B channels are Ra, Ga, and Ba, respectively.

  (Step S111) The second WB gain setting unit 142 of the WB control unit 126 calculates the white balance gain of the reference image from the average values Ra, Ga, Ba for each of the R, G, B channels calculated in Step S110. The white balance gain calculated here corresponds to, for example, the white balance gains WBr and WBb shown in (Expression 1) and (Expression 2).

  (Step S112) The WB conversion unit 144 of the WB control unit 126 reads the white balance gains WBr and WBb calculated in step S111 from the second WB gain setting unit 142 via the switching unit 143 and stores them in the image buffer 107. White balance conversion is executed by applying the white balance gains WBr and WBb to the image data of the actual captured image captured in step S102 (image data after the Debayer processing by the color interpolation processing unit 147).

  (Step S113) The captured image data after white balance correction by the WB conversion unit 144 of the WB control unit 126 is subjected to matrix processing and gamma processing by the correction processing unit 132, and is compressed to Jpeg data by the Jpeg compression unit 133. .

  (Step S114) The Jpeg data converted in Step S113 is stored in the memory card 111a as a Jpeg image file to which information such as a file name and a creation date is added.

  On the other hand, the data creation unit 146 tags the white balance gain obtained from the achromatic subject of the reference image by the second WB gain setting unit 142 with respect to the raw data of the main captured image temporarily stored in the image buffer 107. It is added as information, and saved in the memory card 111a as a RAW image file as described in FIG. At this time, the white balance gain of the first WB gain setting unit 141 previously stored in the memory card 111a in step S102 is replaced with the raw image file added as tag information and stored in the memory card 111a. Alternatively, only the tag information of the raw image file stored in advance may be rewritten.

  Further, the white balance gain obtained from the achromatic object of the reference image by the second WB gain setting unit 142 is added to the raw data of the reference image temporarily stored in the image buffer 107 as tag information, and the raw image of the reference image is added. It may be stored in the memory card 111a as an image file.

  (Step S115) When a method other than the “reference shooting” item 301 is selected in Step S106, and the “color temperature setting” item 302 or the “light source type setting” item 303 in FIG. 7 is selected, the second WB gain of the WB control unit 126 is selected. The setting unit 142 obtains a white balance gain according to these methods and outputs the white balance gain to the WB conversion unit 144. For example, when the “color temperature setting” item 302 is selected, a menu screen for inputting a numerical value such as color temperature: 3500K (4000K, 5200K, etc.) is displayed on the display unit 110, and the user inputs a numerical value. Alternatively, when the “light source type setting” item 303 is selected, the type of the light source is displayed on the display unit 110 such as light source: fluorescent light (incandescent light, sunlight, etc.), and the user selects the light source. Note that the process of setting the color temperature and the light source type and performing the white balance adjustment is a commonly performed process, and a detailed description thereof is omitted here. As described above, after obtaining the white balance gain by a method other than the method of capturing the reference image, the process proceeds to step S112. Note that the processing after step S112 is the same as the case of taking a reference image and adjusting the white balance.

  (Step S116) A series of processing such as photographing processing, white balance processing, and recording processing is terminated.

  As described above, the digital camera 101 according to the present embodiment is configured such that the reference image is displayed when the user gives an instruction for white balance correction to a captured image that has been subjected to white balance adjustment by an auto white balance method or the like. Thus, the correction white balance gain is obtained and applied to the photographed image, so that appropriate white balance adjustment can be performed.

  As a result, it is not necessary to perform a complicated operation such as designating an achromatic region in an image after shooting as in the prior art, and white balance adjustment can be performed easily and appropriately in the digital camera 101.

  In addition, when saving raw data, the white balance gain is stored in association with the raw data as tag information, so when displaying the raw data image on a personal computer or the like, the white balance gain of the tag information is read out and appropriately stored. Images with adjusted white balance can be displayed on the computer screen.

  In particular, the white balance gain added as tag information to the Raw data is replaced with the white balance gain previously added as the tag information of the Raw data when white balance correction is performed by taking a reference image or the like. Since the corrected white balance gain is recorded, the optimal white balance gain can always be stored in association with the Raw data.

(Second Embodiment)
Next, the digital camera 101 according to the second embodiment will be described in detail. Note that the digital camera 101 according to the second embodiment has the same configuration as the digital camera 101 described in the first embodiment. In the first embodiment, the case where white balance adjustment is performed at the time of shooting has been described. However, in this embodiment, white balance can be corrected when a plurality of images that have already been shot are reproduced.

  FIG. 9 is a flowchart showing an operation example of white balance adjustment during reproduction in the present embodiment. It is assumed that a plurality of actual captured images and reference images have already been captured and stored in the memory card 111a. Further, as in the first embodiment, the actual captured image stored in the memory card 111a may be an image that has been subjected to white balance correction immediately after shooting, or may be an image that has not been subjected to white balance correction. Furthermore, in the first embodiment, the reference image is based on an operation that is only for obtaining the correction white balance gain and is not stored in the memory card 111a. However, in the present embodiment, the reference image is also stored in the memory in the same manner as the actual captured image. It is assumed that it is stored in the card 111a. For example, the data creation unit 146 generates a reference image file including information indicating that it is a reference image in the header information of FIG. 4 so that it can be determined that the file is a reference image file. The tag information of the reference image file describes the correction white balance gain obtained from the reference image.

  (Step S201) The user operates various operation buttons of the operation unit 112 to select a reproduction mode, and starts a reproduction process. In FIG. 2, a dedicated playback mode selection button may be provided.

  (Step S202) When the playback mode is selected, the control unit 108 reads out already-captured image data stored in the memory card 111a. Note that the image data read from the memory card 111a may be Jpeg data or Raw data.

  (Step S203) The control unit 108 displays the captured image data read from the memory card 111a in step S201 on the display unit 110. When a raw image file is read from the memory card 111a and displayed on the display unit 110, the image after white balance adjustment is displayed with the white balance gain described in the tag information of the raw image file. Accordingly, the display unit 110 displays an image whose white balance has been adjusted with the white balance gain at the time of shooting.

  (Step S204) As shown in FIG. 6, the user views an image processed by auto white balance and selects whether or not to perform white balance correction. Then, the control unit 108 determines the user's selection. This process is the same as step S104 in the flowchart of FIG. 5 of the first embodiment. For example, as described with reference to FIG. 6, when the “YES” button 208 is selected, the process proceeds to step S205 to start the white balance correction process. On the other hand, when the “NO” button 209 is selected, the white balance correction is not performed, and the process proceeds to step S213 to end the series of processes.

  (Step S <b> 205) The control unit 108 displays a menu for selecting a white balance correction method on the display unit 110. This processing is the same processing as step S105 in the flowchart of FIG. 5 of the first embodiment, and a selection menu screen as shown in FIG. 7 is displayed on the display unit 110, for example.

  (Step S206) The control unit 108 determines whether or not the white balance correction method selected by the user in step S205 is a method for capturing a reference image. This process is the same as step S106 in the flowchart of FIG. 5 of the first embodiment. For example, as described with reference to FIG. 7, when the “reference shooting” item 301 is selected, the process proceeds to step S207 to perform reference shooting. On the other hand, if a method other than the “reference shooting” item 301, or the “color temperature setting” item 302 or the “light source type setting” item 303 in FIG. 7 is selected, the process proceeds to step S212.

  (Step S207) The control unit 108 reads out the raw data of the reference-captured image stored in the memory card 111a and displays it on the display unit 110. For example, as shown in FIG. 10, a list of images that have been taken by reference shooting is displayed. The user selects which reference image white balance gain is applied to the reproduced image displayed in step S203. For example, in FIG. 10, a reference image REF1 is a reference image obtained by photographing the back surface of the lens cap of the digital camera 101 that is colored in an achromatic color. The reference image REF2 is a reference image obtained by photographing a white wall of a house. Further, the reference image REF3 is a reference image obtained by photographing achromatic paper over the entire screen. It should be noted that the date and time when each reference image was taken may be displayed so that a reference image close to the date and time when the reproduced image was taken can be selected. Note that, as described with reference to FIG. 2, the reference image is selected by selecting the reference images displayed in a thick frame in order using the cross key 204 of the operation unit 112 and pressing the confirm button 205. The selection of the reference image displayed in is confirmed.

  (Step S208) The control unit 108 reads the tag information added to the raw data of the reference image determined in step S207 from the memory card 111a, and sets it as a correction white balance gain.

  Here, in the case of the second embodiment, in FIG. 3 of the first embodiment, it is equivalent to the operation of temporarily storing the Raw data read from the memory card 111 a in the image buffer 107 instead of the imaging unit 131. It is. For example, the playback image of the Raw data read from the memory card 111a in step S202 corresponds to the actual captured image of the Raw data captured by the imaging unit 131 in FIG. Further, the reference image of the Raw data read from the memory card 111a in step S208 corresponds to the reference image captured by the imaging unit 131 in FIG. Therefore, the correction white balance gain described in the tag information of the reference image file read from the memory card 111a is set in the second WB gain acquisition unit 142 in FIG. Further, the white balance gain described in the tag information of the RAW image file read from the memory card 111a is set in the first WB gain acquisition unit 141 in FIG. 3 in the process of the previous step S202.

  (Step S209) The WB conversion unit 144 of the WB control unit 126 in FIG. 3 reads the white balance gain set in step S208 from the second WB gain setting unit 142 via the switching unit 143 and stores it in the image buffer 107. In step S202, white balance conversion is executed by applying the white balance gain of the second WB gain setting unit 142 to the raw data of the raw image file read from the memory card 111a. This process is the same as step S112 in the flowchart of FIG. 5 of the first embodiment.

  (Step S210) The image data after the white balance correction by the WB conversion unit 144 of the WB control unit 126 is subjected to matrix processing and gamma processing by the correction processing unit 132, and converted into Jpeg data by the Jpeg compression unit 133. This process is the same as step S113 in the flowchart of FIG. 5 of the first embodiment.

  (Step S211) The Jpeg data converted in Step S210 is stored in the memory card 111a as a Jpeg image file to which information such as a file name and a creation date is added. At this time, the JPEG image file of the reproduction image already stored may be overwritten, or another file may be created.

  On the other hand, the data creation unit 146 adds the white balance gain of the reference image set in the second WB gain setting unit 142 as tag information to the raw data of the reproduction image temporarily stored in the image buffer 107. And stored in the memory card 111a as a raw image file. At this time, the RAW image file of the reproduction image already stored may be overwritten or another file may be created. Alternatively, only the tag information of the raw image file of the reproduced image that has already been stored may be replaced.

  (Step S212) If a method other than the “reference shooting” item 301 is selected in step S206, for example, the “color temperature setting” item 302 or the “light source type setting” item 303 in FIG. 7 is selected, the second WB of the WB control unit 126 is selected. The gain setting unit 142 obtains a white balance gain according to these methods and outputs the white balance gain to the WB conversion unit 144. This process is the same as step S115 in the flowchart of FIG. 5 of the first embodiment. As described above, after obtaining the white balance gain by a method other than the reference image, the process proceeds to step S209. Note that the processing after step S209 is the same as when the reference image is used.

  (Step S213) White balance correction is performed on the reproduced image stored in the memory card 111a, and a series of processes stored in the memory card 111a again is terminated.

As described above, the digital camera 101 according to the present embodiment applies the white balance gain of the captured reference image to the white balance when an instruction for correcting the white balance is given during reproduction of the captured actual captured image. To adjust the white balance appropriately.
[Modification (2) of the second embodiment]
In the flowchart of FIG. 9, the case where the playback images are displayed one by one and the white balance correction is performed has been described. However, a plurality of shot images stored in the memory card 111a are collectively collected. The same white balance correction may be performed.

  For example, first, as shown in FIG. 11, a plurality of captured images (IMG 1 to IMG 6) are displayed on the display unit 110. The image displayed on the display unit 110 displays information for identifying whether or not the image has been subjected to reference photographing as described in the first embodiment and the white balance is corrected. For example, (corrected WB) is displayed below the image IMG6 whose white balance has been corrected. Further, (AWB) is displayed below the images IMG1 to IMG5 taken by the auto white balance method without correcting the white balance. Then, the user uses the cross key 204 and the confirm button 205 to select at least one image that the white balance correction is desired from among the images IMG1 to IMG5 photographed by the auto white balance method without correcting the white balance. .

  As a selection method, images are sequentially sent with the cross key 204, and the confirm button 205 is pressed when the image IMG1 is displayed in a thick frame. Thus, the image IMG1 remains displayed with a thick frame. Further, the images are sequentially sent with the cross key 204, and when the image IMG5 is displayed in a thick frame, the confirm button 205 is pressed. As a result, the image IMG1 and the image IMG5 remain displayed in a thick frame. Next, similarly, the image IMG6 with the white balance corrected is selected. Further, when the “execute” button 401 is selected with the cross key 204 (the “execute” button 401 is displayed in a thick frame) and the confirm button 205 is pressed, tag information is added to the raw data image file of the image IMG6. The stored white balance gain is applied to the images IMG1 and IMG5 to perform white balance conversion. The white balance converted image IMG1 and image IMG5 Jpeg data and Raw data are overwritten and saved. At this time, the tag information of the raw data image file is replaced with the corrected white balance gain.

  In the description of FIG. 11, only one image IMG6 has been corrected for white balance, but even when there are a plurality of images for which white balance has been corrected, any one of them may be selected.

Alternatively, as shown in FIG. 12, a plurality of photographed photographed images and a plurality of reference images are displayed on the display unit 110, and a photographed image to be white balance corrected by the same operation as in FIG. 11. Select multiple reference images and select one reference image with the corrected white balance gain to apply, and apply the white balance gain of the selected reference image to the selected main image at once to correct the white balance. You may make it perform.
[Modification Example of Second Embodiment (2)]
Further, as shown in FIG. 13, the photographing date and time of the image file list 501 of the main photographed image stored in the memory card 111a and the image file list 502 of the reference image are compared, and the book within a predetermined range set in advance. An operation mode may be provided in which a captured image and a reference image are automatically selected and white balance correction is performed collectively.

  In this case, for example, when the user operates various buttons of the operation unit 112 to execute the automatic batch white balance correction mode, the control unit 108 captures the shooting date and time of the main captured image and the reference image stored in the memory card 111a. , And automatically selects which reference image white balance gain is to be applied to which actual captured image, and executes white balance correction.

  Here, as a method for automatically selecting the optimum reference image for the actual captured image, a method for selecting the closest captured date and time for the actual captured image and the reference image can be considered. That is, if the shooting date and time are close, there is a high possibility that the shooting was performed under the same shooting conditions, and the same white balance gain can be applied.

  As an example, when the setting is made to apply the white balance gain of the reference image that is captured within 30 minutes with the same shooting date, the control unit 108 stores the image file stored in the memory card 111a. The main photographic image and the reference image, which have the same photographic date and are photographed within 30 minutes, are extracted. For example, in FIG. 13, the actual captured image abc. Stored in the memory card 111a. raw and bcd. raw and cdf. For the three main captured images of the raw, the reference images aaa.5 satisfying the condition that the imaging date is May 5 and the imaging time is within 30 minutes from 14:30 to 14:35. raw is extracted. Reference image aaa. The white balance gain described in the tag information of the raw is set to the actual captured image abc. raw and bcd. raw and cdf. Apply white balance correction to three raw images. Similarly, the actual captured image def. raw and efg. For the two main photographic images of raw, the reference image bbb. Raw white balance gain is applied. Further, the actual captured image fgh. raw and ghi. raw and hij. For the three actual captured images of raw, the reference image ccc. Raw white balance gain is applied. If a reference image that satisfies the conditions is not found, an error display indicating which actual captured image cannot be corrected in white balance is displayed on the display unit 110 to notify the user, or the selection condition of the reference image is reset. Encourage users.

  In this way, by applying the white balance gain of the reference image having the shooting date and time close to the shooting date and time of the main shooting image, the white balance correction can be automatically performed collectively. In particular, by selecting a reference image that is close to the actual captured image and the captured date and time, there is a high possibility that the same image capturing condition (same ambient light and color temperature is similar), and appropriate white balance correction is performed. be able to.

  As described above, in each embodiment, the digital camera 101 according to the present invention performs reference image shooting when an instruction to correct white balance is given immediately after shooting or during playback of a shot image. Since the white balance gain of the captured reference image can be applied, appropriate white balance adjustment can be performed.

  In the present embodiment, the case where the white balance correction processing is performed by the digital camera 101 has been described. However, the same white balance correction is not limited to the digital camera 101 but may be performed by an apparatus that captures an image or reproduces a captured image. An image processing apparatus that performs processing may be used. For example, a similar white balance correction process may be performed in an image playback apparatus that simply reads out and plays back an image file from the memory card 111a in which the actual captured image and the reference image are stored. The system 102, the mechanical shutter 103, the image sensor 104, the AFE 105, the A / D converter, and the like may not have a part for capturing an image, but may have a part for inputting an image from the memory card 111a or the like.

  Alternatively, the same white balance correction processing is executed by application software that can be operated on a personal computer. In this case, the image processing program of the application software is a program for executing the processing described in the flowchart of FIG. 5 or 9 on the personal computer.

1 is a block diagram illustrating a configuration of a digital camera 101 according to each embodiment. 1 is an external view of a digital camera 101. FIG. 3 is a block diagram showing a configuration of a WB control unit 126. FIG. It is explanatory drawing which shows the structural example of a Raw image file. 4 is a flowchart illustrating white balance correction processing of the digital camera 101 according to the first embodiment. It is explanatory drawing which shows the example of a screen which instruct | indicates execution of white balance correction. It is explanatory drawing which shows the example of a white balance method selection screen. It is explanatory drawing which shows the example of the imaging | photography screen of a reference image. It is a flowchart which shows the white balance correction process of the digital camera 101 which concerns on 2nd Embodiment. It is explanatory drawing which shows the example of a selection screen of a reference image. It is explanatory drawing which shows the example of a screen of collective white balance correction. It is explanatory drawing which shows the other example of a screen of collective white balance correction. It is explanatory drawing for demonstrating the collective white balance correction by a file list.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Digital camera 102 ... Shooting optical system 103 ... Mechanical shutter 104 ... Imaging element 105 ... AFE 106 ... A / D conversion part 107 ... Image buffer 108 ... Control Section 109 ... Memory 110 ... Display section 111 ... Memory card I / F 112 ... Operation section 121 ... Lens control section 122 ... Aperture control section 123 ... Shutter control section 124 ..AF control unit 125 ... AE control unit 126 ... WB control unit 141 ... first WB gain setting unit 142 ... second WB gain setting unit 143 ... switching unit 144 ... WB conversion unit 145 WB correction control unit 146 Data generation unit 147 Color interpolation processing unit 201 Power button 202 Release button 203 Zoom button 2 4 ... cross key 205 ... confirmation button

Claims (9)

Imaging means for converting subject light into an electrical signal to generate image data;
In a digital camera comprising: white balance adjustment means for performing white balance adjustment by applying a predetermined white balance parameter to image data generated by the imaging means,
Correction instruction means for instructing whether or not to execute white balance correction after applying the first white balance parameter to the image data generated by the imaging means and adjusting the white balance;
A reference image capturing unit that captures an achromatic image by the image capturing unit and generates reference image data when execution of white balance correction is instructed by the correction instruction unit;
A digital camera comprising: a second white balance parameter obtaining unit that obtains a second white balance parameter from the reference image data. The digital camera according to claim 1, wherein
An image buffer for temporarily storing image data captured by the imaging means;
When execution of white balance correction is instructed by the correction instructing means, the second white balance parameter is applied to the image data stored in the image buffer to perform white balance adjustment and obtain final image data And a modified image data acquisition means. The digital camera according to claim 2,
The image buffer temporarily stores a plurality of pieces of image data captured by the imaging unit,
The corrected image data acquisition means uses the second white balance parameter of the image data to which the second white balance parameter is applied among the plurality of pieces of image data as the second white balance among the plurality of pieces of image data. A digital camera that performs white balance adjustment by applying it to image data to which parameters are not applied. The digital camera of claim 1.
Recording means is further provided for recording the second white balance parameter obtained by the second white balance parameter acquisition means and the image data before white balance adjustment photographed by the imaging means in association with each other on a storage medium. A digital camera characterized by The digital camera according to claim 4, wherein
The recording means stores the first white balance parameter in the storage medium as tag information of image data before white balance adjustment, and after the second white balance parameter acquisition means calculates a second white balance gain, The digital camera, wherein the second white balance parameter is stored in place of the first white balance parameter stored as the tag information. The digital camera according to any one of claims 1 to 5,
Display means for displaying the image data after the white balance adjustment on the screen as an image by applying the first white balance parameter by the white balance adjustment means;
The digital camera characterized in that the correction instructing means displays message information for confirming whether or not to execute white balance correction on the screen of the display means. The digital camera according to any one of claims 1 to 6,
2. The digital camera according to claim 1, wherein the image data before white balance adjustment is image data in Raw format, and the image data after white balance adjustment is image data in Jpeg format. Image input means for inputting image data;
In an image processing apparatus comprising: white balance adjustment means for performing white balance adjustment by applying a predetermined white balance parameter to image data input by the image input means;
Correction instruction means for instructing whether or not to execute white balance correction after applying the first white balance parameter to the image data input by the image input means and adjusting the white balance;
Reference image input means for inputting reference image data of an achromatic color image when execution of white balance correction is instructed by the correction instruction means;
An image processing apparatus comprising: a second white balance parameter obtaining unit that obtains a second white balance parameter from the reference image data. An image processing program executed using a computer,
Image input procedure for inputting image data,
A white balance adjustment procedure for performing white balance adjustment by applying a predetermined white balance parameter to the image data input in the image input procedure;
A correction instruction procedure for instructing whether or not to execute white balance correction after the white balance adjustment by applying the first white balance parameter to the image data input in the image input procedure;
A reference image input procedure for inputting reference image data of an achromatic image when execution of white balance correction is instructed by the correction instruction procedure;
A second white balance parameter acquisition procedure for obtaining a second white balance parameter from the reference image data.

Images