JP2007312005A - Image processor, image processing method, and image processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve efficient and highly-accurate color reproduction that reduces color distortion while improving color reproducibility of image output corresponding to a photographed scene. <P>SOLUTION: A part 719 for deciding a color-conversion-definition correction method selects a saturation compression correction when the photographed scene discriminated by a scene discrimination part 718 is a photographed scene of scenery, and also, the part 719 selects a hue compression correction when it is a photographed scene of a person so as to decide a correction method for a reference-color conversion definition. A correction proportion calculator 720 calculates correction proportions showing that at which level the correction executed by the decided correction method is added to the reference-color conversion definition. A color-conversion-definition corrector 723 corrects color-reproduction characteristics of the reference-color conversion definition with the decided correction method. When the correction of the color-reproduction characteristics is executed; a color conversion definition for each scene is selected corresponding to the correction method, so as to execute the correction while allowing the color-reproduction characteristics of the color conversion definition for each scene to work on the reference-color conversion definition at the level of the correction proportions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image processing apparatus, an image processing method, and an image processing program that perform color conversion on image data based on color conversion definition data and output the image data.

  In recent years, in addition to the development of computers, the development of communication networks, the emergence of large-capacity storage media, etc., the demand for printing out digital image data with high image quality has increased with the spread of scanners and digital cameras. ing.

  On the other hand, with conventional silver halide film prints and prints obtained by film scanning, the average brightness of the entire image is corrected as desired by the user so that the desired brightness or density is achieved visually. At the time of output, adjustment of exposure time and image processing have been performed.

  Similarly, even if an image shot with a general digital still camera (hereinafter referred to as “DSC”) is output without any image processing, a preferable image cannot be obtained. Is eager to do.

  The reason why image data with visually unfavorable brightness is generated is that in normal shooting, the light source conditions such as forward light, backlight, strobe, etc. fluctuate variously, and there is a large area with large luminance deviation in the image. This is because it occurs. For this reason, in addition to correction of the average luminance, additional correction using values calculated by discriminant analysis and multiple regression analysis is necessary. However, in the discriminant regression analysis method, the parameters calculated from the strobe shooting scene and the backlight scene are very similar, and thus it is difficult to discriminate the shooting scene.

  Therefore, in the technique of Patent Document 1, the luminance average is obtained by deleting the high luminance region and the sub luminance region from the luminance histogram indicating the cumulative number of luminance pixels (frequency number) and further limiting the frequency number. A value is calculated, and a difference between the average value and the reference luminance is obtained as a correction value.

  Further, in the technique of Patent Document 2, the average brightness of the extracted face candidate region is calculated with respect to the entire image, and when the amount of deviation is large, the shooting scene (backlight shooting or flash close-up shooting) is determined, The permissible width of the judgment criterion as a face area is adjusted.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique for obtaining a desired print by determining a scene of image data, determining brightness and correcting the brightness, and changing the brightness. Furthermore, Patent Document 4 discloses a technique for performing image correction by analyzing image data, calculating shadows, highlights, and exposure from the histogram, and creating a correction lookup table based on the shadows, highlights, and exposures. .

  Also, when printing digital image data that has been shot, unlike analog output, by performing image processing, the human skin color, sky blue, grass green, which are characteristic color regions in the image, are processed. There is a demand for higher image quality in order to reproduce such a memory color portion with visually desirable brightness and a desired color.

On the other hand, in Patent Document 5, a memory color region extracted when printing image data is subjected to a masking process, thereby performing a color correction process different from other areas, and visually storing the memory color. Discloses a technique for reproducing a preferable color.
JP 2002-247393 A JP 2000-148980 A JP 2004-343809 A JP 2006-018739 A JP-A-6-121159

  However, in film shooting, images are output with color reproduction characteristics according to the shooting scene by taking a picture using a film for portrait shooting or a film for landscape shooting. When outputting, it has been difficult to output an image with color reproduction characteristics according to the shooting scene.

  That is, although the technique of Patent Document 1 can reduce the influence of a region with a large luminance deviation in a backlight or strobe shooting scene, the brightness of the face region is inappropriate in a shooting scene having a person as a main subject. In addition, the change in saturation and hue due to the change in lightness was large, and color distortion occurred and was not practical. In addition, the technique of Patent Document 2 has a problem in that the effect of compensating for the identification of a face area cannot be obtained when image data obtained by shooting in backlight or near a strobe is not applicable to a typical composition. .

  Further, in the technique of Patent Document 3, when output is performed in a color processing apparatus that handles colors such as a color printer after image processing, the hue connection from the bright skin color of the person to the shadows deteriorates, and a desired print can be obtained. It was difficult to get. This is a method of defining a reference color space when performing output in an image processing apparatus such as a color printer, and adjusting each image processing apparatus to the color space. Because there is a local color space, it is necessary to make corrections according to the specific characteristics of each device, and the output characteristics of color printers have strong nonlinearity, making accurate mapping difficult. .

  Therefore, recently, in order to accurately reproduce digitized color image data and to mutually convert color information between different devices, a color such as a three-dimensional lookup table (hereinafter referred to as “3D-LUT”) or a color profile is used. Color conversion using conversion definition data is often used. By performing color conversion using this color conversion definition data, it is possible to perform gradation adjustment according to the shooting scene. However, since actual images are taken in various situations and there are various exposure conditions, color conversion must be performed according to the brightness of the situations, and color conversion definition data corresponding to all conditions Creating and using was unrealistic.

  Therefore, even in the technique of Patent Document 4 in which shadow, highlight, and exposure are calculated from the histogram, and a correction lookup table is created based on the calculation result to correct the image, the hue connection deteriorates. The image quality was not practical.

  On the other hand, in the technique of Patent Document 5 in which the memory color is visually reproduced as a preferable color when printing out, the memory color is used in order to perform color correction processing different from the other areas for the image area of the extracted memory color. A discontinuity occurs between the image area and the image area of another color and a pseudo contour is generated, which is not practical.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide efficient and high-precision that can improve color reproducibility of image output according to a shooting scene and reduce color distortion. It is to realize proper color reproduction.

In order to solve the above problems, the invention described in claim 1
In an image processing apparatus that outputs image data by performing color conversion based on color conversion definition data,
Discriminating means for discriminating a shooting scene by performing a scene discrimination process on the image data;
Calculating means for calculating a correction ratio based on the shooting scene determined by the determining means;
Correction means for adding a correction according to the shooting scene for the color reproduction characteristics of the color conversion definition data to a degree based on the correction ratio;
Color conversion means for color-converting the image data based on the color conversion definition data corrected by the correction means;
It is characterized by having.

The invention according to claim 2 is the invention according to claim 1,
A storage means for storing a plurality of color conversion definition data having different color reproduction characteristics;
The correction means includes
The specified color conversion definition data by causing the color reproduction characteristics of the color conversion definition data corresponding to the shooting scene to act on the color reproduction characteristics of the color conversion definition data specified in advance to a degree based on the correction ratio. It is characterized by correcting the color reproduction characteristics.

The invention according to claim 3 is the invention according to claim 2,
The correction means includes
When the constituent requirements of the subject of the photographic scene determined by the determining means are different from a predetermined reference scene, correction is performed by applying color conversion definition data having a high hue compression ratio to the specified color conversion definition data. It is a feature.

The invention according to claim 4 is the invention according to claim 2 or 3,
The correction means includes
When the luminance configuration of the photographic scene determined by the determining unit is different from a predetermined reference scene, correction is performed by applying color conversion definition data having a high saturation compression rate to the specified color conversion definition data. It is said.

The invention according to claim 5 is the invention according to any one of claims 1 to 4,
The discrimination means includes
An occupancy ratio calculating unit that divides the image data into an area composed of a combination of predetermined brightness and hue, and calculates, for each area, the ratio of the divided area to the entire image data as an occupancy ratio;
An index calculation means for calculating an index for specifying a shooting scene by multiplying the occupation ratio for each area calculated by the occupation ratio calculation means by a coefficient set in advance according to shooting conditions;
Scene discriminating means for discriminating a shooting scene of the image data based on the index calculated by the index calculating means;
It is characterized by having.

The invention according to claim 6 is the invention according to claim 5,
The index calculation means calculates a plurality of indexes for specifying the shooting scene,
The scene discrimination means includes
The imaging scene of the image data is determined for each of the plurality of calculated indexes.

The invention according to claim 7 is the invention according to claim 6 or 7,
The index calculating means includes
First index calculation means for calculating a first index that quantitatively indicates that the shooting scene is a flash shooting scene;
Second index calculating means for calculating a second index quantitatively indicating that the shooting scene is a backlight scene;
Third index calculating means for calculating a third index quantitatively indicating that the shooting scene is a person shooting scene;
Have
The scene discrimination means includes
A shooting scene of the image data is determined based on the first index, the second index, and the third index.

The invention according to claim 8 provides:
In an image processing method for color-converting and outputting image data based on color conversion definition data,
A determination step of determining a shooting scene by performing a scene determination process on the image data;
A calculation step of calculating a correction ratio based on the shooting scene determined in the determination step;
A correction step of adding correction according to the shooting scene with respect to the color reproduction characteristics of the color conversion definition data to a degree based on the correction ratio;
A color conversion step of color-converting the image data based on the color conversion definition data corrected in the correction step;
It is characterized by including.

The invention according to claim 9 is the invention according to claim 8,
The correction step includes
The specified color conversion definition data by causing the color reproduction characteristics of the color conversion definition data corresponding to the shooting scene to act on the color reproduction characteristics of the color conversion definition data specified in advance to a degree based on the correction ratio. It is characterized by correcting the color reproduction characteristics.

The invention according to claim 10 is the invention according to claim 9,
The correction step includes
When the constituent requirements of the subject of the shooting scene determined in the determination step are different from a predetermined reference scene, correction is performed by applying color conversion definition data having a high hue compression rate to the specified color conversion definition data. It is a feature.

The invention according to claim 11 is the invention according to claim 9 or 10,
The correction step includes
When the luminance configuration of the photographic scene determined in the determination step is different from a predetermined reference scene, correction is performed by causing color conversion definition data having a high saturation compression rate to act on the specified color conversion definition data. It is said.

The invention according to claim 12 is the invention according to any one of claims 8 to 11,
The discrimination step includes
An occupancy ratio calculating step of dividing the image data into an area composed of a combination of predetermined brightness and hue, and calculating the ratio of the divided area in the entire image data as an occupancy ratio for each area;
An index calculation step of calculating an index for identifying a shooting scene by multiplying the occupation rate for each area calculated in the occupation rate calculation step by a coefficient set in advance according to the shooting conditions;
A scene determination step of determining a shooting scene of the image data based on the index calculated in the index calculation step;
It is characterized by including.

The invention according to claim 13 is the invention according to claim 12,
The index calculating step calculates a plurality of indices for specifying the shooting scene,
The scene discrimination step includes
The imaging scene of the image data is determined for each of the plurality of calculated indexes.

The invention according to claim 14 is the invention according to claim 12 or 13,
The index calculation step includes
A first index calculating step for calculating a first index quantitatively indicating that the shooting scene is a flash shooting scene;
A second index calculating step for calculating a second index quantitatively indicating that the shooting scene is a backlight scene;
A third index calculating step of calculating a third index quantitatively indicating that the shooting scene is a person shooting scene;
Have
The scene discrimination step includes
A shooting scene of the image data is determined based on the first index, the second index, and the third index.

The invention according to claim 15 provides a computer,
Discriminating means for discriminating a shooting scene by performing scene discrimination processing on image data,
Calculating means for calculating a correction ratio based on the photographic scene determined by the determining means;
Correction means for adding correction according to the shooting scene to the color reproduction characteristics of the color conversion definition data used for color conversion of the image data in a degree based on the correction ratio,
Color conversion means for color-converting the image data based on the color conversion definition data corrected by the correction means;
It is characterized by making it function as.

The invention according to claim 16 is the invention according to claim 15,
Further function as storage means for storing a plurality of color conversion definition data having different color reproduction characteristics,
The correction means includes
The specified color conversion definition data by causing the color reproduction characteristics of the color conversion definition data corresponding to the shooting scene to act on the color reproduction characteristics of the color conversion definition data specified in advance to a degree based on the correction ratio. It is characterized by correcting the color reproduction characteristics.

The invention according to claim 17 is the invention according to claim 16,
The correction means includes
When the constituent requirements of the subject of the photographic scene determined by the determining means are different from a predetermined reference scene, correction is performed by applying color conversion definition data having a high hue compression ratio to the specified color conversion definition data. It is a feature.

The invention according to claim 18 is the invention according to claim 16 or 17,
The correction means includes
When the luminance configuration of the photographic scene determined by the determining unit is different from a predetermined reference scene, correction is performed by applying color conversion definition data having a high saturation compression rate to the specified color conversion definition data. It is said.

The invention according to claim 19 is the invention according to any one of claims 15 to 18,
The discrimination means includes
An occupancy ratio calculating unit that divides the image data into an area composed of a combination of predetermined brightness and hue, and calculates, for each area, the ratio of the divided area to the entire image data as an occupancy ratio;
An index calculation means for calculating an index for specifying a shooting scene by multiplying the occupation ratio for each area calculated by the occupation ratio calculation means by a coefficient set in advance according to shooting conditions;
Scene discriminating means for discriminating a shooting scene of the image data based on the index calculated by the index calculating means;
It is characterized by having.

The invention according to claim 20 is the invention according to claim 19,
The index calculation means calculates a plurality of indexes for specifying the shooting scene,
The scene discrimination means includes
The imaging scene of the image data is determined for each of the plurality of calculated indexes.

The invention according to claim 21 is the invention according to claim 19 or 20,
The index calculating means includes
First index calculation means for calculating a first index that quantitatively indicates that the shooting scene is a flash shooting scene;
Second index calculating means for calculating a second index quantitatively indicating that the shooting scene is a backlight scene;
Third index calculating means for calculating a third index quantitatively indicating that the shooting scene is a person shooting scene;
Have
The scene discrimination means includes
A shooting scene of the image data is determined based on the first index, the second index, and the third index.

  According to the present invention, the color reproduction characteristics of the color conversion definition data are photographed in order to add correction according to the photographing scene to the color conversion characteristics of the color conversion definition data with the degree of the correction ratio calculated based on the photographing scene. It can be variably adjusted according to the scene. For this reason, it is possible to improve the color reproducibility of the image output according to the shooting scene.

  In addition, when the constituent requirements of the subject are different from the reference scene, color conversion definition data having a high hue compression rate is applied to the color conversion definition data defined in advance. For example, the main subject is a shooting scene of a person. In this case, color conversion is performed by compressing the hue of the skin color area. In addition, when the luminance configuration is different from the reference scene, color conversion definition data with a high saturation compression rate is applied. For example, when a scene with high luminance is a shooting scene of a main subject, the memory color blue Or color conversion that compresses the saturation of the green area. For this reason, a change in the color balance of the subject can be suppressed.

  In addition, since color conversion definition data is created by correcting the color reproduction characteristics according to the shooting scene, it is not necessary to provide color conversion definition data for each shooting scene in advance. Therefore, efficient and highly accurate color reproduction can be realized.

  Hereinafter, an embodiment of an image processing apparatus according to the present invention will be described in detail with reference to FIGS. First, the configuration of the image processing apparatus in the present embodiment will be described.

  FIG. 1 is a perspective view showing an example of the appearance of the image processing apparatus 1. As shown in FIG. 1, the image processing apparatus 1 is provided with a magazine loading unit 3 for loading a photosensitive material on one side of a housing 2. Inside the housing 2 are provided an exposure processing unit 4 for exposing the photosensitive material, and a print creating unit 5 for developing and drying the exposed photosensitive material to create a print. On the other side surface of the housing 2, a tray 6 for discharging the print created by the print creation unit 5 is provided.

  In addition, a CRT (Cathode Ray Tube) 8 as a display unit, a film scanner unit 9 that is a device for reading a transparent original, a reflective original input unit 10, and an operation unit 11 are provided on the upper portion of the housing 2. The CRT 8 reproduces and displays image data to be printed on a display image. Further, the housing 2 includes an image reading unit 14 capable of reading image data recorded on various digital recording media, and an image writing unit 15 capable of writing (outputting) image data on various digital recording media. Is provided.

  The image reading unit 14 includes a PC card adapter 14a and a floppy (registered trademark) disk adapter 14b, and a PC card 13a and a floppy disk 13b can be inserted therein. The PC card 13a and the floppy disk 13b record a plurality of frame image data captured by a digital camera.

  The image writing unit 15 includes a floppy disk adapter 15a, an MO adapter 15b, and an optical disk adapter 15c, and can be loaded with an optical disk 16c such as a floppy disk 16a, MO 16b, CD-R, or DVD-R. Has been. In FIG. 1, an image processing apparatus 1 that creates a print by exposing and developing a photosensitive material is taken as an example. However, the print creation method is not limited to this, and for example, an inkjet method, an electrophotographic method, or the like. A heat sensitive method, a sublimation method, or the like may be used.

<Configuration of Main Parts of Image Processing Apparatus 1>
FIG. 2 shows a main part configuration of the image processing apparatus 1. As shown in FIG. 2, the image processing apparatus 1 includes a control unit 7, an exposure processing unit 4, a print creation unit 5, a film scanner unit 9, a reflection original input unit 10, an image reading unit 14, a communication unit (input) 32, The image writing unit 15, the data storage unit 71, the operation unit 11, the display unit 8, and the communication unit (output) 33 are configured.

  The control unit 7 is configured by a microcomputer, and configures the image processing apparatus 1 by cooperation of various control programs stored in a storage unit such as a ROM (Read Only Memory) and a CPU (Central Processing Unit). Control the operation of each part.

  Based on the input signal from the operation unit 11, the control unit 7 reads the image data read from the film scanner unit 9 and the reflective document input unit 10, the image data read from the image reading unit 14, and the communication unit 32 from an external device. The image data input via the above is subjected to image processing to generate exposure image data, which is output to the exposure processing unit 4. Further, the image processing unit 70 performs a conversion process corresponding to the output form on the image processed image data, and outputs the converted image data.

  The exposure processing unit 4 exposes an image to the photosensitive material and outputs the photosensitive material to the print creating unit 5. The print creating unit 5 develops the exposed photosensitive material and dries it to create a service size, high-vision size, panorama size print P1, A4 size print P2, and business card size print P3.

  The film scanner unit 9 reads a frame image recorded on a transparent original such as a developed negative film N or a reversal film imaged by an analog camera and converts it into digital image data of the frame image. The reflection original input unit 10 reads an image on the print P by a flat bed scanner and converts it into digital image data.

  The image reading unit 14 reads frame image information recorded on the PC card 13 a and the floppy disk 13 b and transfers the frame image information to the control unit 7. The image reading unit 14 includes, as the image transfer unit 30, a PC card adapter 14a, a floppy disk adapter 14b, and the like. The image reading unit 14 reads frame image data recorded on the PC card 13 a and the floppy disk 13 b and transfers the frame image data to the control unit 7.

  The image writing unit 15 includes a floppy disk adapter 15a, an MO adapter 15b, and an optical disk adapter 15c as the image transport unit 31, and according to instructions from the control unit 7, the floppy disk 16a, the MO 16b, and the optical disk 16c. Write image data to.

  The data storage unit 71 stores and sequentially stores image data and order information (information indicating how many prints are to be created from images of which frames, information on print sizes, etc.).

  The operation unit 11 includes, for example, a keyboard, a mouse, a touch panel, and the like, and outputs a signal corresponding to a pressed key or a designated coordinate position on the display unit 8 to the control unit 7 as an input signal. The display unit 8 displays image information and the like according to the display control signal input from the control unit 7.

  A communication unit (input) 32 receives image data representing a captured image, a print command signal, and the like from an external device, and a communication unit (output) 33 receives image data representing a captured image after image processing, Attached order information is transmitted to the external device.

<Internal Configuration of Image Processing Unit 70>
FIG. 3 shows an internal configuration of the image processing unit 70. As shown in FIG. 3, the image processing unit 70 includes an image adjustment processing unit 701, a film scan data processing unit 702, a reflection original scan data processing unit 703, an image data format decoding processing unit 704, a CRT specific processing unit 706, a printer specific A processing unit A707, a printer specific processing unit B708, and an image data format creation processing unit 709 are provided.

  A film scan data processing unit 702 and a reflection document scan data processing unit 703 perform a calibration operation unique to the film scanner unit 9 and negative / positive reversal (negative document) for the image data input from the film scanner unit 9 and the reflection document input unit 10, respectively. In this case, processing such as dust flaw removal, contrast adjustment, granular noise removal, and sharpening enhancement is performed, and processed image data is output to the image adjustment processing unit 701. In addition, the film size, the negative / positive type, information relating to the main subject optically or magnetically recorded on the film, information relating to the photographing conditions (for example, information content described in APS), and the like are also output to the image adjustment processing unit 701. .

  The image data format decoding processing unit 704 restores a compression code and expresses color data according to the data format of the image data input from the image transfer unit 30 or the communication unit (input) 32 according to the data format of the image data. By performing processing such as method conversion, the data is converted into a data format suitable for calculation in the image processing unit 70, and output to the image adjustment processing unit 701.

  The image adjustment processing unit 701 performs image processing to be described later on the input image data to generate digital image data for image formation optimized for viewing on the output device, and a CRT specific processing unit 706, printer specific processing unit A 707, printer specific processing unit B 708, image data format creation processing unit 709, and data storage unit 71.

  In the optimization process, for example, when display on a CRT display monitor compliant with the sRGB standard is assumed, the optimal color reproduction is performed within the color gamut of the sRGB standard. Also, assuming output to silver salt photographic paper, processing is performed so that optimum color reproduction is obtained within the color gamut of the silver salt photographic paper. In addition to color gamut compression, gradation compression from 16 bits to 8 bits, reduction of the number of output pixels, and processing to cope with the color reproduction characteristics of the output device are also included. Furthermore, it goes without saying that tone compression processing such as noise suppression, sharpening, gray balance adjustment, saturation adjustment, or dodging processing is performed.

  The CRT specific processing unit 706 performs a process such as changing the number of pixels and color matching on the image data input from the image adjustment processing unit 701 as necessary, and combines the information with information that needs to be displayed, such as control information. Image data is output to the CRT 8.

  The printer-specific processing unit A707 performs printer-specific calibration processing, color matching, pixel number change processing, and the like as necessary, and outputs processed image data to the exposure processing unit 4. When an external printer 51 such as a large-format ink jet printer can be connected to the image processing apparatus 1, a printer specific processing unit B708 is provided for each connected printer apparatus. The printer-specific processing unit B708 performs printer-specific calibration processing, color matching, pixel number change, and the like, and outputs processed image data to the external printer 51.

  An image data format creation processing unit 709 converts the image data input from the image adjustment processing unit 701 into various general-purpose image formats represented by JPEG, TIFF, Exif, and the like as necessary. The completed image data is output to the image transport unit 31 and the communication unit (output) 33.

  It should be noted that the film scan data processing unit 702, the reflected original scan data processing unit 703, the image data format decoding processing unit 704, the image adjustment processing unit 701, the CRT specific processing unit 706, the printer specific processing unit A707, and the printer specific shown in FIG. The divisions of the processing unit B708 and the image data format creation processing unit 709 are provided to assist understanding of the functions of the image processing unit 70, and are not necessarily realized as physically independent devices. Alternatively, it may be realized as a type of software processing performed by a single CPU.

  As illustrated in FIG. 3, the image adjustment processing unit 701 includes a scene analysis unit 710, a color conversion definition creation unit 711, and a color conversion definition storage unit 730. The color conversion definition storage unit 730 includes a readable / writable memory area such as an HDD or a semiconductor memory. The color conversion definition storage unit 730 includes a 3D-LUT created by a standard color conversion definition creation unit 721 and a scene-specific color conversion definition creation unit 722 to be described later. Or, a preset 3D-LUT is stored. In the present embodiment, the color conversion definition creating unit 711 is described as creating and correcting a 3D-LUT, but a color profile may be created as color conversion definition data.

  FIG. 4A shows the internal configuration of the scene analysis unit 710. As shown in FIG. 4A, the scene analysis unit 710 includes a ratio calculation unit 712, an index calculation unit 713, and an image processing condition calculation unit 714. As shown in FIG. 4B, the ratio calculation unit 712 includes a color system conversion unit 715, a histogram creation unit 716, and an occupation rate calculation unit 717.

  The color system conversion unit 715 converts the RGB values of the captured image data into the HSV color system. The HSV color system represents image data with three elements of hue, saturation, and brightness. In the present embodiment, “brightness” represents “brightness” that is generally used unless otherwise noted. In the following description, V (0 to 255) of the HSV color system is used as “lightness”, but a unit system representing the brightness of any other color system may be used.

  The histogram creation unit 716 creates a two-dimensional histogram by dividing the photographed image data into regions composed of a predetermined combination of hue and brightness, and calculating the cumulative number of pixels for each of the divided regions. In addition, the histogram creation unit 716 divides the captured image data into predetermined regions including a combination of the distance from the outer edge of the captured image data and the brightness, and calculates the cumulative number of pixels for each of the divided regions. Thus, a two-dimensional histogram is created. Note that the photographed image data may be divided into regions composed of combinations of distance from the outer edge of the image, brightness, and hue, and a cumulative pixel count may be calculated for each region to create a three-dimensional histogram. .

  The occupancy ratio calculation unit 717 is a first occupancy ratio (see Table 1) that indicates the ratio of the cumulative number of pixels calculated for each region divided by the combination of brightness and hue to the total number of pixels (the entire captured image data). Is calculated. The occupation ratio calculation unit 717 also displays a second occupation ratio indicating the ratio of the cumulative number of pixels calculated for each region divided by the combination of the distance from the outer edge of the captured image data and the brightness to the total number of pixels. (See Table 4).

  The index calculation unit 713 multiplies the first occupancy calculated for each region by a first coefficient (see Table 2) set in advance (for example, by discriminant analysis) according to the shooting conditions. As a result, the index 1 for specifying the shooting scene is calculated. Here, the shooting scene indicates a light source condition when shooting a subject, such as direct light, backlight, strobe light, and exposure conditions such as under shooting.

  The index 1 as the first index is for separating an image that should be determined as a “flash shooting scene” as a shooting scene from other shooting scenes. Shooting using a strobe is often performed when shooting indoors or in close proximity, where the light source is insufficient. Further, when photographing using a strobe is performed, a luminance structure is often obtained in which a main subject such as a person's face in a photographed image becomes brighter than the background. For this reason, the index 1 serves as a guideline indicating composite characteristics unique to shooting in a flash shooting scene.

  When calculating the index 1, the index calculation unit 713 uses coefficients of different signs for a predetermined high brightness skin color hue area and a hue area other than the high brightness skin color hue area. Here, the predetermined high lightness skin color hue region includes regions 170 to 224 in the lightness value of the HSV color system. Further, the hue area other than the predetermined high brightness skin color hue area includes at least one high brightness area of the blue hue area (hue values 161 to 250) and the green hue area (hue values 40 to 160).

  In addition, the index calculation unit 713 multiplies the first occupancy calculated for each region by a second coefficient (see Table 3) set in advance according to the shooting conditions to obtain the sum, An index 2 for specifying the scene is calculated.

  The index 2 as the second index is for separating an image that should be determined as a “backlight scene” from other shooting scenes. In addition, shooting in the backlight is often performed outdoors. Further, an image obtained by shooting during backlighting often has a luminance configuration such that the background color such as the sky is photographed brightly, and main subjects such as human faces are photographed darker than the background. For this reason, the index 2 serves as a guideline indicating composite characteristics unique to photographing in a backlight scene.

  When calculating the index 2, the index calculation unit 713 uses coefficients of different signs in the intermediate brightness area of the flesh color hue area (hue values 0 to 39, 330 to 359) and the brightness areas other than the intermediate brightness area. . The intermediate lightness area of the flesh color hue area includes lightness values of 85 to 169. The brightness area other than the intermediate brightness area includes, for example, a shadow area (brightness values 26 to 84).

  Further, the index calculation unit 713 multiplies the second occupancy calculated for each region by a third coefficient (see Table 5) set in advance according to the shooting conditions to obtain the sum, An index 3 for specifying the scene is calculated.

  The index 3 quantitatively indicates only an image that should be determined as a “strobe shooting scene” or a “backlight scene” as a shooting scene. In addition, the index 3 indicates the difference in brightness between the center of the captured image and the outer edge side between the back-light shooting and the strobe shooting. When calculating the index 3, the index calculation unit 713 uses coefficients having different values depending on the distance from the outer edge side of the captured image.

  In addition, the index calculation unit 713 multiplies the average luminance value of the skin color in the vicinity of the center of the entire image area of the photographed image data by a fourth coefficient set in advance according to the photographing condition to obtain a sum. Then, an index 4 for specifying the shooting scene is calculated. More preferably, not only the average brightness value of the skin color in the image center portion of the captured image data, but also the difference value between the maximum brightness value and the average brightness value of the captured image data, the brightness standard deviation, the average brightness value in the image center portion, the image Each of the comparison values (see equation (8) described later) between the difference value between the skin color maximum brightness value and the skin color minimum brightness value and the skin color average brightness value is multiplied by a fourth coefficient set in advance according to the shooting conditions. Then, the index 4 is calculated by taking the sum.

  The index 4 quantitatively indicates only an image that should be determined as a “strobe shooting scene” or “under shooting scene” as a shooting scene. In addition, the index 4 indicates the difference in light-dark relationship between the center of the captured image and the outer edge side between strobe shooting and under shooting, and distribution information in a luminance histogram.

  When calculating the index 4, the index calculation unit 713 calculates the average brightness value of the skin color at the center of the captured image data, the difference value between the maximum brightness value and the average brightness value of the image, the brightness standard deviation, and the average at the center of the image. The comparison value of the brightness value, the difference value between the flesh color maximum brightness value and the flesh color minimum brightness value and the flesh color average brightness value is used. The brightness value here is an index representing brightness, An index representing brightness (for example, a brightness value of the HSV color system) may be used.

  In addition, the index calculation unit 713 performs a face candidate region extraction process that extracts a region (face candidate region) that is estimated to correspond to the face of a person in the entire image region of the captured image data. The ratio occupied in the image area is calculated as index 5. As an example of the face candidate region extraction method, a shape pattern peculiar to each part of a person (for example, a shape pattern representing a head outline, a face outline, etc.) is searched based on captured image data, and the detected shape pattern An area estimated to correspond to a person's face is set according to the size, orientation, and the positional relationship between each part of the person represented by the shape pattern and the person's face.

  In addition, another shape pattern different from the detected shape pattern is searched, the consistency of the previously detected region as the face of the person is obtained, the region that is a candidate for the face image is extracted, and the captured image of the face image is extracted The ratio to the entire area is calculated. In addition to the face image extraction method for extracting a face image from captured image data, a region estimated as a face image may be extracted using a background removal method for removing a background image from captured image data. Note that the average brightness value of the skin color in at least the central portion in the entire image area of the photographed image data may be calculated as the index 5.

  The index 5 as the third index quantitatively indicates only an image that should be discriminated as “portrait shooting scene”, “landscape shooting scene” or “person + landscape shooting scene” as a shooting scene. For example, if the index 5 is 0.8 or more, it is determined that the scene is a “portrait shooting scene”. If the index 5 is 0.2 to 0.8, it is “person + landscape shooting scene”. It is determined as “landscape shooting scene”. Here, a subject to be photographed and a subject to be photographed such as a background are referred to as “object” in the present embodiment.

  The index calculation unit 713 may calculate the index 6 by multiplying each of the index 1 and the index 3 by a coefficient set in advance according to the shooting condition, and more preferably, the index 1 and the index 3 are calculated. In addition, the index 6 may be calculated by multiplying each of the indices 5 by a coefficient set in advance according to the shooting conditions and taking the sum (see Expression (10)).

  Furthermore, the index calculation unit 713 may calculate the index 7 by multiplying each of the index 2 and the index 3 by a coefficient set in advance according to the shooting condition, and more preferably, the index 2 The index 7 may be calculated by multiplying each of the index 3 and the index 5 by a coefficient set in advance according to the shooting condition to obtain a sum (see Expression (11)).

  FIG. 4C shows the internal configuration of the image processing condition calculation unit 714. As illustrated in FIG. 4C, the image processing condition calculation unit 714 includes a scene determination unit 718, a color conversion definition correction method determination unit 719, and a correction ratio calculation unit 720.

  The scene discrimination unit 718 discriminates a shooting scene (luminance configuration of light source condition and exposure condition, object configuration of person or landscape) based on the indexes 1 to 7 calculated by the index calculation unit 713.

  The color conversion definition correction method determination unit 719 determines a correction method for the 3D-LUT (color conversion definition data) stored in the color conversion definition storage unit 730 according to the shooting scene determined by the scene determination unit 718. Here, the color reproduction characteristics are the brightness and saturation characteristics of the color space that can be reproduced and output by the output device. Even if the output device is the same type, the color reproduction characteristics will differ if the output medium is different. Come.

  A 3D-LUT corresponding to the color reproduction characteristics of the output device is created by a standard color conversion definition creation unit 721 described later. Further, a 3D-LUT for each shooting scene is created by a color conversion definition creation unit for each scene 722 described later. Hereinafter, the 3D-LUT created by the standard color conversion definition creation unit 721 is “standard color conversion definition”, and the 3D-LUT created by the scene-specific color conversion definition creation unit 722 is “personal color conversion definition” for each shooting scene. This is called “landscape color conversion definition”.

  Such various 3D-LUTs are stored in the color conversion definition storage unit 730, and a 3D-LUT (hereinafter referred to as “reference color conversion definition”) serving as a reference at the time of shooting is determined by user settings, initial settings, and the like. It is set in advance. For example, the color conversion definition for a person is set as the reference color conversion definition for a user who frequently shoots a person as a subject, and the color conversion definition for a landscape is set for a user who frequently shoots a landscape.

  A color conversion definition correction method determination unit 719 determines a correction method for the reference color conversion definition according to the shooting scene. Specifically, for example, when it is determined that a human face candidate area is narrow with respect to the entire captured image and is a captured image centered on a landscape, that is, a “landscape captured scene”, the reference color conversion definition The saturation compression correction for compressing the saturation of the LUT is selected as the LUT correction method. If it is determined that the human face candidate region is wide and “person photographed scene” with respect to the entire photographed image, hue compression correction for compressing the hue of the reference color conversion definition is selected as the correction method.

  Further, the color conversion definition correction method determination unit 719 determines a gradation conversion method for the captured image data in accordance with the captured scene determined by the scene determination unit 718. For example, when it is determined that the scene is a front light scene, the gradation conversion method A for correcting the translation (offset) of the pixel value of the input captured image data is selected. If it is determined that the scene is a backlight scene or an undershoot scene, a gradation conversion method B that performs gamma correction on the pixel value of the input captured image data is selected. Further, when it is determined that the scene is a flash photography scene, a gradation conversion method C for selecting gamma correction and parallel movement correction for the pixel value of the inputted photographed image data is selected.

  The image adjustment processing unit 701 selects a gradation conversion curve corresponding to the determined gradation conversion method from a plurality of gradation conversion curves (1D-LUT) set in advance, and follows the gradation conversion curve. Tone conversion is performed on photographed image data. Since the gradation conversion method is a known technique, the description thereof is omitted.

  The correction ratio calculation unit 720 adds a correction ratio indicating to what degree the correction by the correction method selected and determined by the color conversion definition correction method determination unit 719 is added to the reference color conversion definition in the shooting scene. Calculate based on

  FIG. 4D shows the internal configuration of the color conversion definition creation unit 711. The color conversion definition creation unit 711 includes a standard color conversion definition creation unit 721, a scene-specific color conversion definition creation unit 722, and a color conversion definition correction unit 723, as shown in FIG.

  The standard color conversion definition creation unit 721 is a functional unit that creates a 3D-LUT corresponding to the color reproduction characteristics of an output device such as the CRT 8 or the external printer 51, and includes a colorimeter, a densitometer, and the like that measure chromaticity. Configured. The standard color conversion definition creation unit 721 measures the color patch displayed on the CRT 8 or the color patch printed by the external printer 51, and based on the color measurement result and the image data that is the basis of the color patch. The standard color conversion definition is created (standard color conversion definition creation processing in FIG. 20).

  Since this standard color conversion definition can be created in a favorable environment with little change in exposure conditions, the shooting scene is a front light scene and a person + landscape shooting scene, and the shot image is shot at an appropriate exposure. Used for data color conversion. Indicators 1 to 6 are set in advance in the standard color conversion definition.

  The scene-specific color conversion definition creation unit 722 creates a scene-specific color conversion definition by performing various adjustment processes on the standard color conversion definition created by the standard color conversion definition creation unit 721. For example, the color conversion definition for a person corresponding to a person photographing scene is previously adjusted so that the skin color of a person who is a subject (object) is reproduced with a visually preferable skin color according to a change in brightness. In addition, the color conversion definition for landscape corresponding to a landscape shooting scene reproduces the color of an object that accounts for a large proportion of the landscape image, such as the sky blue or the green color of plants, in a visually preferred color according to the change in brightness. Such adjustments are made in advance.

  The timing at which the standard color conversion definition creation unit 721 and the scene-specific color conversion definition creation unit 722 create the 3D-LUT is not particularly limited. For example, the standard color conversion definition creation unit 721 creates the 3D-LUT before inputting captured image data. Is desirable.

  The color conversion definition correction unit 723 corrects the color reproduction characteristics of the reference color conversion definition by the correction method determined by the color conversion definition correction method determination unit 719. In this correction, a scene-specific color conversion definition is selected according to the correction method, and the color reproduction characteristics of the scene-specific color conversion definition are applied to the reference color conversion definition with the degree of the correction ratio calculated by the correction ratio calculation unit 720. Correct as follows. For this reason, the corrected color conversion definition newly created by correction by the color conversion definition correcting unit 723 has the color reproduction characteristics of the output device, and the color reproduction characteristics according to the photographed image correspond to the photographing scene. It will be reflected in the proportion.

  The image adjustment processing unit 701 performs the correction color conversion definition created by the color conversion definition correction unit 723, that is, based on the correction color conversion definition in which the color reproduction characteristics are corrected based on the shooting scene of the input shooting image data. Performs color conversion of the captured image data and outputs it.

<Specific operation of image processing apparatus>
Next, specific operations of the image processing apparatus 1 will be described with reference to FIGS. FIG. 5 is a flowchart showing the processing content of the scene determination processing executed by the image adjustment processing unit 701.

  As shown in FIG. 5, the image adjustment processing unit 701 first divides the captured image data into predetermined image areas, and sets the first and second occupancy ratios indicating the ratio of the divided areas to the entire captured image data. An occupancy ratio calculation process is performed (step S1).

  Then, based on the occupation rate calculated by the ratio calculation unit 712, at least the average luminance value of the skin color at the center of the image of the captured image data, and a coefficient set in advance according to the shooting conditions, the shooting scene is specified. The indices 1 to 7 are calculated (step S2). Next, a shooting scene is determined based on the index calculated in step S2, and an image processing condition for the shot image data is determined according to the determination result (step S3).

  6 and 11 are flowcharts showing the processing contents of the occupation ratio calculation processing executed in step S1.

  First, in the first occupancy rate calculation process of FIG. 6, the RGB values of the input captured image data are converted into the HSV color system (step S10). Next, the photographed image data is divided into regions composed of combinations of predetermined brightness and hue, and a two-dimensional histogram is created by calculating the cumulative number of pixels for each divided region (step S11). Here, the area division of the captured image data will be described in detail.

  The lightness (V) is 0-25 (v1), 26-50 (v2), 51-84 (v3), 85-169 (v4), 170-199 (v5), 200-224 (v6). , 225 to 225 (v7). Hue (H) is a flesh color hue region (H1 and H2) having a hue value of 0 to 39 and 330 to 359, a green hue region (H3) having a hue value of 40 to 160, and a blue hue region having a hue value of 161 to 250. It is divided into four areas (H4) and a red hue area (H5).

  Note that the red hue region (H5) is not used in the following calculation because it is found that the contribution to the determination of the shooting scene is small. The flesh color hue area is further divided into a flesh color area (H1) and other areas (H2). Hereinafter, among the flesh-colored hue regions (H = 0 to 39, 330 to 359), the hue ′ (H) that satisfies the following formula (1) is defined as the flesh-colored region (H1), and the region that does not satisfy the formula (1) is ( H2).

10 <Saturation (S) <175,
Hue '(H) = Hue (H) + 60 (when 0 ≤ Hue (H) <300),
Hue '(H) = Hue (H) -300 (when 300 ≤ Hue (H) <360),
Luminance (Y) = InR x 0.30 + InG x 0.59 + InB x 0.11 (A)
As
Hue '(H) / Luminance (Y) <3.0 × (Saturation (S) / 255) +0.7 (1)
Therefore, the number of divided areas of the captured image data is 4 × 7 = 28. In addition, it is also possible to use the brightness (V) in the formulas (A) and (1). InR, InG, and InB are RGB values of the input image data.

When the two-dimensional histogram is created by the histogram creation unit 716, the occupation rate calculation unit 717 calculates a first occupation rate (step S12). Assuming that the first occupancy calculated in the divided area composed of the combination of the lightness area vi and the hue area Hj is Rij, the first occupancy in each divided area is expressed as shown in Table 1.

<Calculation method of index 1 and index 2>
Next, a method for calculating the index 1 and the index 2 will be described. Table 2 shows the first coefficient necessary for calculating the index 1 that quantitatively indicates the accuracy of strobe shooting, that is, the brightness state of the face candidate area at the time of strobe shooting, for each divided area. The coefficient of each divided area shown in Table 2 is a weighting coefficient by which the first occupancy rate Rij of each divided area shown in Table 1 is multiplied, and is set in advance according to the shooting conditions.

  FIG. 7 shows a lightness (V) -hue (H) plane. According to Table 2, a positive coefficient is used for the first occupancy calculated from the region (r1) distributed in the high brightness skin color hue region in FIG. 7, and the blue hue region (hue other than that) A negative coefficient is used for the first occupancy calculated from r2).

  FIG. 9 shows the first coefficient in the skin color region (H1) and the first coefficient in the other region (green hue region (H2)) as a coefficient curve that continuously changes over the entire brightness. It is. According to Table 2 and FIG. 9, in the high brightness region (V = 170 to 224), the sign of the first coefficient in the skin color region (H1) is positive, and the sign in the other region is negative. Is different.

If the first coefficient in the lightness region vi and the hue region Hj is Cij, the sum of the Hk regions for calculating the index 1 is defined as in Expression (2).

Accordingly, the sum of the H1 to H4 regions is expressed by the following formulas (2-1) to (2-4).
Sum of H1 regions = R11 x (-44.0) + R21 x (-16.0) + ... + R71 x (-11.3) (2-1)
Sum of H2 regions = R12 x 0.0 + R22 x 8.6 + ... + R72 x (-11.1) (2-2)
Sum of H3 regions = R13 x 0.0 + R23 x (-6.3) + ... + R73 x (-10.0) (2-3)
Sum of H4 region = R14 x 0.0 + R24 x (-1.8) + ... + R74 x (-14.6) (2-4)

The index 1 is defined as in Expression (3) using the sum of the H1 to H4 regions shown in Expressions (2-1) to (2-4).
Index 1 = sum of H1 region + sum of H2 region + sum of H3 region + sum of H4 region + 4.424 (3)

Table 3 shows, for each divided region, the second coefficient necessary for calculating the index 2 that quantitatively indicates the accuracy as backlight photographing, that is, the brightness state of the face candidate region at the time of backlight photographing. The coefficient of each divided area shown in Table 3 is a weighting coefficient by which the first occupancy rate Rij of each divided area shown in Table 1 is multiplied, and is set in advance according to the shooting conditions.

  FIG. 8 shows a lightness (V) -hue (H) plane. According to Table 3, a negative coefficient is used for the occupancy calculated from the region (r4) distributed in the intermediate lightness of the flesh color hue region in FIG. 8, and from the low lightness (shadow) region (r3) of the flesh color hue region. A positive coefficient is used for the calculated occupation ratio. FIG. 10 shows the second coefficient in the skin color region (H1) as a coefficient curve that continuously changes over the entire brightness. According to Table 3 and FIG. 10, the sign of the second coefficient of the intermediate lightness region of the skin color hue region with the lightness value of 85 to 169 (v4) is negative, and the lightness value of 26 to 84 (v2, v3). It can be seen that the sign of the low brightness area is positive, and the signs of the coefficients in both areas are different.

When the second coefficient in the lightness area vi and the hue area Hj is Dij, the sum of the Hk areas for calculating the index 2 is defined as in Expression (4).

Accordingly, the sum of the H1 to H4 regions is expressed by the following formulas (4-1) to (4-4).
Sum of H1 regions = R11 x (-27.0) + R21 x 4.5 + ... + R71 x (-24.0) (4-1)
Sum of H2 regions = R12 x 0.0 + R22 x 4.7 + ... + R72 x (-8.5) (4-2)
Sum of H3 regions = R13 x 0.0 + R23 x 0.0 + ... + R73 x 0.0 (4-3)
Sum of H4 region = R14 x 0.0 + R24 x (-5.1) + ... + R74 x 7.2 (4-4)

The index 2 is defined as in Expression (5) using the sum of the H1 to H4 regions shown in Expressions (4-1) to (4-4).
Index 2 = sum of H1 area + sum of H2 area + sum of H3 area + sum of H4 area + 1.554 (5)
Since the index 1 and the index 2 are calculated based on the brightness and hue distribution amount of the captured image data, the index 1 and the index 2 are effective for determining a captured scene when the captured image data is a color image.

<Calculation method for index 3>
Next, a method for calculating the index 3 will be described. In calculating the index 3, second occupancy rate calculation processing according to the flowchart of FIG. 11 is performed.

  First, the RGB values of the photographed image data are converted into the HSV color system (step S20), and the photographed image data is divided into regions each composed of a combination of the distance from the outer edge of the photographed image and the brightness, and for each divided region. A two-dimensional histogram is created by calculating the cumulative number of pixels (step S21).

  FIGS. 12A to 12D show four regions n1 to n4 divided according to the distance from the outer edge of the image of the captured image data. A region n1 shown in FIG. 12A is an outer frame, a region n2 shown in FIG. 12B is a region inside the outer frame, and a region n3 shown in FIG. A region n4 shown in FIG. 12D is an inner region and is a central region of the captured image. In addition, the brightness is divided into seven regions v1 to v7 as described above. Therefore, when the captured image data is divided into regions composed of combinations of the distance from the outer edge of the captured image and the brightness, the number of divided regions is 4 × 7 = 28.

When the two-dimensional histogram is created, the occupation ratio calculation unit 717 calculates a second occupation ratio (step S22). If the second occupancy calculated in the divided area composed of the combination of the brightness area vi and the image area nj is Qij, the second occupancy in each divided area is expressed as shown in Table 4.

Table 5 shows the third coefficient necessary for calculating the index 3 for each divided region. The coefficient of each divided area shown in Table 5 is a weighting coefficient that is multiplied by the second occupancy rate Qij of each divided area shown in Table 4, and is set in advance according to the shooting conditions.

FIG. 13 shows the third coefficient in the image areas n1 to n4 as a coefficient curve that continuously changes over the entire brightness. If the third coefficient in the brightness area vi and the image area nj is Eij, the sum of the image area nk for calculating the index 3 is defined as in Expression (6).

Accordingly, the sum of the n1 to n4 regions is represented by the following formulas (6-1) to (6-4).
Sum of n1 region = Q11 × 40.1 + Q21 × 37.0 + ... + Q71 × 22.0 (6-1)
Sum of n2 regions = Q12 × (-14.8) + Q22 × (-10.5) +... + Q72 × 0.0 (6-1)
n3 area sum = Q13 × 24.6 + Q23 × 12.1 +... + Q73 × 10.1 (6-1)
Sum of n4 regions = Q14 x 1.5 + Q24 x (-32.9) + ... + Q74 x (-52.2) ... (6-1)

The index 3 is defined as in Expression (7) using the sum of the n1 to n4 regions shown in Expressions (6-1) to (6-4).
Index 3 = sum of n1 regions + sum of n2 regions + sum of n3 regions + sum of n4 regions−12.6201 (7)
The index 3 is calculated based on a compositional feature (distance from the outer edge of the image of the photographed image data) according to the lightness distribution position of the photographed image data, and therefore, the photographing scene of the monochrome image as well as the color image is discriminated. It is also effective.

<Calculation method of index 4>
Next, the index 4 calculation process executed in the index calculation unit 713 will be described with reference to the flowchart of FIG.

  First, the luminance Y is calculated from the RGB values of the photographed image data using the formula (A), and the average luminance value x1 of the skin color area in the center of the image of the photographed image data is calculated (step S23). Here, the central portion of the image is, for example, a region composed of a region n3 and a region n4 in FIG. Next, a difference value x2 between the maximum luminance value and the average luminance value of the captured image data is calculated (step S24).

Next, the standard deviation x3 of the luminance of the photographed image data is calculated (step S25), and the average luminance value x4 at the center of the image is calculated (step S26). Next, a comparison value x5 between the difference value between the maximum luminance value Yskin_max and the minimum luminance value Yskin_min of the skin color area in the photographed image data and the average luminance value Yskin_ave of the skin color area is calculated (step S27). This comparison value x5 is expressed as the following equation (8).
x5 = (Yskin_max−Yskin_min) / 2−Yskin_ave (8)

Next, the index 4 is calculated by multiplying each of the values x1 to x5 calculated in steps S23 to S27 by a fourth coefficient set in advance according to the shooting condition and taking the sum (step S28). ). The index 4 is defined as the following formula (9).
Index 4 = 0.06 x x 1 + 1.13 x x 2 + 0.02 x x 3 + (-0.01) x x 4 + 0.03 x x 5-6.50 (9)
The index 4 has not only compositional characteristics of the image of the captured image data but also luminance histogram distribution information, and is particularly effective for distinguishing between a strobe shooting scene and an under shooting scene.

<Calculation method of indicators 5-7>
In addition, as described above, the index calculation unit 713 calculates the ratio of the face candidate area estimated to correspond to the face of the person in the entire area of the captured image as the index 5. In addition, the index 6 is defined as the formula (10) using the index 1, the index 3, and the index 5, and the index 7 is defined as the formula (11) using the index 2, the index 3, and the index 5. To calculate each.
Index 6 = 0.46 × Index 1 + 0.61 × Index 3 + 0.01 × Index 5-0.79 (10)
Index 7 = 0.58 x Index 2 + 0.18 x Index 3 + (-0.03) x Index 5 + 3.34 (11)
Here, the weighting coefficient by which each index is multiplied in Expression (10) and Expression (11) is set in advance according to the shooting conditions.

<Determination of image processing conditions>
Next, the image processing condition determination process (step S3 in FIG. 5) executed in the image processing condition calculation unit 714 will be described with reference to the flowchart in FIG.

  First, based on the values of indexes 1 to 7 calculated by the index calculation unit 713, the shooting scene of the captured image data is determined (step S30). Here, a method of discriminating the shooting scene will be described.

  In FIG. 16A, 60 images are taken under each light source condition of forward light, backlight, and strobe, and index 6 and index 7 are calculated for a total of 180 digital image data. The value of index 7 is plotted. According to FIG. 16A, when the value of index 5 is greater than 0.5, there are many flash photography scenes, the value of index 5 is 0.5 or less, and the value of index 6 is greater than −0.5. It can be seen that there are many backlight scenes. In this way, the shooting scene can be quantitatively determined based on the values of the index 6 and the index 7.

  Furthermore, by adding the index 4 to the index 5 and the index 6 that can discriminate each shooting scene of the front light, the backlight, and the strobe, the shooting scene can be discriminated three-dimensionally, and the discrimination accuracy of the shooting scene is further improved. Is possible. The index 4 is particularly effective for discriminating between a strobe shooting scene in which color conversion adjustment for darkening the entire image is performed and an under shooting scene in which color conversion adjustment for brightening the entire image is performed.

FIG. 16B is a graph in which the index 4 and the index 6 of an image in which the index 6 is larger than 0.5 are calculated and plotted among 60 captured images of the strobe shooting scene and the under shooting scene. According to FIG. 16B, it can be seen that when the value of index 4 is greater than 0, there are many flash shooting scenes, and when the value of index 4 is 0 or less, there are many under shooting scenes. Table 6 shows the contents of determination of the shooting scene according to the values of the index 4, the index 6, and the index 7.

In a photographic image taken in a stroboscopic scene, the subject is irradiated with stroboscopic light, so that the brightness of the image area of the subject is higher than that of the background. In addition, in a captured image in a backlight scene or an under-photographed scene, a low-luminance region occurs in the image. For this reason, a photographed image photographed in a flash photography scene, a backlight scene, or an under photography scene is an image having a high luminance variation within the image area.

  As described above, an area with a difference in brightness is generated in the image area according to the shooting scene. In this embodiment, the distribution of the image area having the difference in brightness of the captured image data is referred to as “luminance configuration”, and this luminance configuration is different from a predetermined reference shooting scene (hereinafter referred to as “reference scene”). The color conversion definition data such as 3D-LUT is corrected.

  For example, if the value of the index 5 is 0.2 or less, it is determined that the face candidate area for the photographed image is narrow and the scene is a landscape shooting scene with a landscape as a main subject. It is determined that the face candidate area is wide and the person scene is mainly a person. If the index 5 is between 0.2 and 0.8, it can be determined that the person is a person and a landscape shooting scene in which a person and a landscape are mixed as a main subject. As described above, from the index 5, it is possible to determine the shooting scene based on the size of the image area of the subject included in the shot image.

  By discriminating the shooting scene, it is possible to determine the color and distribution of the subject constituting the shot image. In this embodiment, the color and distribution of the image area of the subject are referred to as “subject constituent requirements”. When the constituent requirements of the subject are different from the reference scene, the color conversion definition data is corrected.

  When the photographic scene is determined in step S30, the gradation conversion method for the photographic image data is determined as described above according to the determined photographic scene (step S31). Then, a correction method for the reference color conversion definition is determined according to the shooting scene.

  Specifically, when the shooting scene determined by the scene determination unit 718 is a landscape shooting scene, saturation compression correction is selected. The saturation compression correction is a correction for compressing the saturation characteristic of the reference color conversion definition in the saturation direction and the brightness direction. FIG. 17 illustrates an example of saturation characteristics. FIG. 17 is a graph with lightness (L *) in the L * C * h color system on the vertical axis and saturation (C *) on the horizontal axis.

  For example, if the reference color conversion definition has the saturation characteristic c1 shown in FIG. 17, the saturation characteristic c1 is lowered by a predetermined level in the saturation direction, and the high saturation point c10 at which the saturation characteristic c1 takes the maximum saturation. Is lowered by a predetermined level in the brightness direction. Thus, the saturation characteristic c1 of the reference color conversion definition is corrected to the saturation characteristic c2 compressed in the saturation direction and the lightness direction, and corrected color conversion definitions having different saturation compression rates are created. In addition, a photographed image whose main subject is a landscape is color-converted into an image with a high saturation in the middle lightness area, so that the color is prevented from jumping in the high lightness area.

  If the shooting scene determined by the scene determination unit 718 is a person shooting scene, hue compression correction is selected. Hue compression correction is correction for compressing the hue characteristics of the reference color conversion definition. FIG. 18 illustrates an example of hue characteristics. FIG. 18 is a graph in which chromaticity a * and b * in the L * a * b * color system are plotted on the horizontal axis and the vertical axis, respectively.

  For example, it is assumed that the orange (5YR) hue characteristic c3 and the red (5R) hue characteristic c4 of the reference color conversion definition are as shown in FIG. Since the hue characteristics c3 and c4 are represented by a linear line, it is shown that captured image data having a constant hue of orange to red including human skin color faithfully reproduces the hue of the data as it is. Yes.

  A broken line BL in FIG. 18 indicates an angle bisector of the a * axis and the b * axis. In the hue compression correction, the hue characteristics c3 and c4 are compressed toward the broken line BL side. At this time, in the low saturation region where the saturation is low, the degree of compression of the hue characteristics c3 and c4 is increased. Thereby, the hue characteristics c3 and c4 of the reference color conversion definition are corrected to the saturation characteristics c4 and c5 compressed in the direction of the broken line BL, and corrected color conversion definitions having different hue compression rates are created. In addition, a photographed image with a person as the main subject is subjected to color conversion by increasing the density of the skin color region image, and the face image can be made clearer.

  It should be noted that the degree of compression in the saturation compression correction and the hue compression correction is preferably determined according to the degree to which a human can tolerate a change in color balance, and a specific value is obtained experimentally or empirically.

  When the correction method for the reference color conversion definition is determined in step S32, a correction ratio indicating how much the color reproduction characteristics of the scene-specific color conversion definition are applied to the reference color conversion definition is calculated (step S33). ). The correction ratio is calculated from the difference in the constituent requirements of the subject of the photographic scene and the difference in the luminance configuration determined by the scene determination unit 718 with respect to the reference scene.

  The correction ratio is set in advance by curves f1 and f2 as shown in FIG. The curve f2 indicates that when the object configuration and the luminance configuration of the shooting scene determined by the scene determination unit 718 are greatly different from the reference scene, the correction ratio is increased, and the correction ratio is decreased as the reference scene is closer. Is shown. On the other hand, the curve f1 indicates that the correction ratio is increased when the object configuration and the luminance configuration of the reference scene are significantly different from the shooting scene, and the correction ratio is decreased as the reference scene is closer.

The correction ratio calculation unit 720 calculates the correction ratios F1 and F2 from the values on the curves f1 and f2 corresponding to the degree of difference between the object configuration and the luminance configuration of the shooting scene with respect to the reference scene. The correction ratios F1 and F2 are calculated by the following equation (12).

  For example, when the person color conversion definition is set as the reference color conversion definition, if it is determined that the shooting scene is a backlight scene, a strobe shooting scene, or an under shooting scene and is a landscape shooting scene, Quantify the difference in object composition. This value is calculated from the difference from the index 5 calculated from the captured image data as described above with the index 5 set in the reference color conversion definition as a reference. That is, when the index 5 of the person color conversion definition is 1 and the calculated index 5 is 0.2, the difference is calculated as 0.8.

  Then, the correction ratios F1 and F2 are calculated from the values of the curves f1 and f2 on the boundary that divides the reference scene and the shooting scene of FIG. 19A by 4: 1 (0.8: 0.2). . At this time, assuming that the correction ratio F1 is calculated as 0.25 and the correction ratio F2 is 0.75, the reference color conversion definition includes the saturation compression correction added to the landscape color conversion definition at a ratio of 75%. In effect, a correction color conversion definition is created. For this reason, 75% of the saturation compression correction is added to the correction color conversion definition while leaving the saturation characteristics of the reference color conversion definition by 25%.

  Further, when the standard color conversion definition is set as the reference color conversion definition and the shooting scene is determined to be a person shooting scene, the degree of difference in object configuration in the shot image is quantified. That is, when the standard color conversion definition index 5 is 0.5 and the calculated human photographing scene index 5 is 0.9, the difference is 0.8 ((0.9−0.5). /(1-0.5)).

  At this time, if the correction ratio F1 is calculated as 0.25 and the correction ratio F2 is calculated as 0.75 as in the above example, the hue compression correction added to the person color conversion definition is set to 75 in the reference color conversion definition. The correction color conversion definition is created by operating for%. For this reason, 75% of hue compression correction is added to the correction color conversion definition while leaving the hue characteristics of the reference color conversion definition by 25%.

  FIG. 19B shows an example of the hue characteristic c7 of the corrected color conversion definition when the hue compression correction is added by 75%. As shown in FIG. 19B, the hue characteristic c7 of the correction color conversion definition has a characteristic close to the hue characteristic c6 of the person color conversion definition, but on the side of the hue characteristic c7 of the reference color conversion definition. It also has a characteristic, and two hue characteristics are mixed.

  Also, for example, when it is determined that the shooting scene is a backlight scene, a person shooting scene, and an under shooting scene, there is a correction color conversion definition that compresses the hue of the skin color and compresses the saturation of the area such as green in the background. Created. When it is determined that the scene is a strobe shooting scene, a person shooting scene, or an under shooting scene, a correction color conversion definition is created that compresses the hue of the skin color and suppresses the saturation compression of the background portion.

As described above, the correction color conversion definition is created from the combination of the reference color conversion definition and the scene-specific color conversion definition corresponding to the shooting scene, so that the correction color having at least two or more 3D-LUT color reproduction characteristics is obtained. A conversion definition is created.

  Note that the correction ratio may be set by setting the ratio of the reference color conversion definition and the scene-specific color conversion definition to a linear linear ratio, and a new correction LUT may be created. It is desirable to set so as not to damage. Further, although the correction ratio is calculated from the curves f1 and f2 in FIG. 19A, a linear linear line may be set in advance and calculated based on the straight line.

<LUT creation>
Next, a specific operation of the color conversion definition creation unit 711 will be described with reference to FIGS. FIG. 20 is a flowchart showing the processing contents of the standard color conversion definition creating process executed by the standard color conversion definition creating unit 721.

  First, the standard color conversion definition creating unit 721 displays and prints out the color patch CP shown in FIG. 21 on the CRT 8 or the external printer 51 before starting the processing of the flowchart of FIG. Specifically, as shown in FIG. 21, patch image data (sRGB) having 729 points of grid point data that is divided into 9 × 9 × 9 equal parts and composed of RGB of 32 bits is created, and based on the patch image data To output a color patch CP.

The standard color conversion definition creation unit 721 acquires input signal values (R _j , G _j , B _j , (j = 1 to N)) for three primary independent colors corresponding to the patch image data (step S40). . Then, color measurement of the color patch P2 is performed (step S41), and the color measurement result is acquired as an output signal value in the xyz color space (step S42).

Next, the input signal values (r _i , g _i , b _i , (i = 1 to N)) of the patch image data and the output signal values (R _j , G _j , B _j , ( j = 1 to N)) is created to create the 3D-LUT 24 (step S43).

  Subsequently, the standard color conversion definition creation unit 721 interpolates an N × N × N stage 3D-LUT by three-dimensional interpolation such as volume interpolation or spline interpolation, and the number of division levels for each hue is changed from N to M. Increase to stage (M> N). The M stages are obtained by M = (N−1) × L + 1. For example, the number of division levels is increased from 9 to 33 to create a 3D-LUT.

  Here, as a complementing method of the 3D-LUT 24, three-dimensional interpolation, linear interpolation, area interpolation, volume interpolation, or the like of a known technique can be applied, and volume interpolation is more preferable. As volume interpolation, for example, tetrahedral interpolation, triangular prism (prism) interpolation, hexahedron (cube) interpolation, pyramid interpolation, spline interpolation, and the like can be adopted, and spline interpolation is more preferable in terms of accuracy of color reproducibility.

  The 3D-LUT obtained by this standard color conversion definition creation processing is stored in the color conversion definition storage unit 730 as a standard color conversion definition. The standard color conversion definition creation method is not particularly limited, and may be created using a known method.

  The scene-specific color conversion definition creation unit 722 adjusts the color reproduction characteristics of the standard color conversion definition created by the standard color conversion definition creation unit 721 according to the shooting scene, and creates a 3D-LUT for each shooting scene. Stored in the color conversion definition storage unit 730.

  Next, a specific operation of the correction color conversion definition creation unit 711 will be described. The correction color conversion definition creating unit 711 creates a correction color conversion definition from a combination of the color conversion definition for each scene corresponding to the correction method and the reference color conversion definition. For example, it is assumed that the reference color conversion definition stores the input signal value 240 and the output signal value 242 shown in FIG.

  At this time, when the above-described hue compression correction is performed as shown in FIG. 22, for example, the output signal value of the reference color conversion definition is converted into chromaticity data of the L * a * b * color system in the flesh color to red region AR. Conversion is performed (output signal value 244). Then, the hue of chromaticity data close to an achromatic color having no color is compressed to obtain an output signal value 246. Next, the chromaticity data of the output signal value 246 is returned to the xyz value.

  Then, by adding the signal value obtained by multiplying the output signal value 246 by the correction ratio F2 and the signal value obtained by multiplying the output signal value 242 of the reference color conversion definition by the correction ratio F1, an output signal of the correction color conversion definition The value 248 is generated. Then, a correction color conversion definition is created by associating the output signal value 248 with the input signal value 240.

  In order to obtain the color gamut necessary for color reproduction, the color output of the color gamut boundary and the color conversion definition for each scene are accurately used as input signals for important colors such as human skin color, sky blue, and trees green. Therefore, a correction color conversion definition may be created using the important color as adjustment data.

  Further, the color conversion definition for each scene is obtained by re-interpolating the reference color conversion definition by three-dimensional interpolation such as spline interpolation, and dividing the number of division levels for each hue from N to M (M> N, for example, M = (N−1). ) × L + 1) After creating a highly accurate (M × M × M stage) 3D-LUT, color correction may be performed so that the output signal value of the color conversion definition for each scene is obtained. Good.

  As described above, according to the present embodiment, the correction ratio is calculated based on the photographic scene determined from the photographic image data, and the hue characteristic and the saturation characteristic of the color conversion definition for each scene are compared with the reference color conversion definition at the correction ratio. By making it act, a correction color conversion definition is created. For this reason, since the standard color conversion definition and the color conversion definition for each scene can be corrected according to the shooting scene, it is possible to improve the color reproducibility of a subject such as a person's face or landscape.

  In addition, since a new correction color conversion definition is created by correcting a 3D-LUT stored and set in advance according to the shooting scene, it is not necessary to set a huge number of 3D-LUTs. In addition, since color conversion is performed using one corrected color conversion definition that corrects the color reproduction characteristics, it is possible to prevent connection of hues in the captured image and discontinuity between the face image and the background image. it can. Therefore, efficient and highly accurate color reproduction can be realized.

  In addition, embodiment mentioned above is an example to which this invention is applied, The applicable range is not restricted to what was mentioned above. For example, the indices 1 to 7 may be obtained from a reduced image created by performing reduction processing on input captured image data. As a method for reducing the image size, a known method (for example, a bilinear method, a bicubic method, a nearest neighbor method, or the like) can be used. The reduction ratio is not particularly limited, but is preferably about 1/2 to 1/10 of the original image from the viewpoint of processing speed and the accuracy of the scene discrimination process. By performing scene discrimination by reducing the image size in this way, the processing time can be shortened compared to the case where scene discrimination is performed using original image data.

The perspective view which shows the example of an external appearance of an image processing apparatus. The block diagram which shows the internal structural example of an image processing apparatus. The block diagram which shows an example of a principal part structure of an image process part. The figure which shows an example of each internal structure of a scene analysis part (a), a ratio calculation part (b), an image processing condition calculation part (c), and a color conversion definition preparation part (d). The flowchart which shows the processing content performed in an image adjustment process part. The flowchart which shows the processing content of a 1st occupation rate calculation process. The figure which shows the lightness-hue plane, the area | region r1, and the area | region r2. The figure which shows the brightness-hue plane and the area | region r3 and the area | region r4. The figure which shows the curve showing an example of a 1st coefficient. The figure which shows the curve showing an example of a 2nd coefficient. The flowchart for demonstrating the processing content of a 2nd occupation rate calculation process. The figure which shows the area | region determined according to the distance from the outer edge of the image of picked-up image data. The figure which shows the curve showing an example of a 3rd coefficient according to area | region. The flowchart which shows the processing content of the parameter | index 4 calculation process. The flowchart which shows the processing content of image processing condition determination processing. The plot figure which shows the relationship between an imaging | photography scene and the indexes 4-7. The figure for demonstrating the saturation compression method. The figure for demonstrating the hue compression method. (A) The figure for demonstrating the calculation method of a correction ratio, (b) The figure which shows an example of the saturation characteristic of a correction color conversion definition. 10 is a flowchart for explaining the processing content of standard color conversion definition creation processing. The figure which shows an example of a color patch. The figure for demonstrating the correction process of a reference color conversion definition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image processing apparatus 5 Print preparation part 8 Display part 51 External printer 70 Image processing part 701 Image adjustment process part 710 Scene analysis part 711 Color conversion definition preparation part 712 Ratio calculation part 713 Index calculation part 714 Image processing condition calculation part 715 System conversion unit 716 Histogram creation unit 717 Occupancy calculation unit 718 Scene determination unit 719 Correction method determination unit 720 Correction ratio calculation unit 721 Standard color conversion definition creation unit 722 Scene-specific creation unit 723 Color conversion definition correction unit 730 Color conversion definition storage unit

Claims (21)

In an image processing apparatus that outputs image data by performing color conversion based on color conversion definition data,
Discriminating means for discriminating a shooting scene by performing a scene discrimination process on the image data;
Calculating means for calculating a correction ratio based on the shooting scene determined by the determining means;
Correction means for adding a correction according to the shooting scene for the color reproduction characteristics of the color conversion definition data to a degree based on the correction ratio;
Color conversion means for color-converting the image data based on the color conversion definition data corrected by the correction means;
An image processing apparatus comprising: A storage means for storing a plurality of color conversion definition data having different color reproduction characteristics;
The correction means includes
The specified color conversion definition data by causing the color reproduction characteristics of the color conversion definition data corresponding to the shooting scene to act on the color reproduction characteristics of the color conversion definition data specified in advance to a degree based on the correction ratio. The image processing apparatus according to claim 1, wherein the color reproduction characteristics of the image processing apparatus are corrected. The correction means includes
When the constituent requirements of the subject of the photographic scene determined by the determining means are different from a predetermined reference scene, correction is performed by applying color conversion definition data having a high hue compression ratio to the specified color conversion definition data. The image processing apparatus according to claim 2. The correction means includes
When the luminance configuration of the photographic scene determined by the determining unit is different from a predetermined reference scene, correction is performed by applying color conversion definition data having a high saturation compression rate to the specified color conversion definition data. The image processing apparatus according to claim 2 or 3. The discrimination means includes
An occupancy ratio calculating unit that divides the image data into an area composed of a combination of predetermined brightness and hue, and calculates, for each area, the ratio of the divided area to the entire image data as an occupancy ratio;
An index calculation means for calculating an index for specifying a shooting scene by multiplying the occupation ratio for each area calculated by the occupation ratio calculation means by a coefficient set in advance according to shooting conditions;
Scene discriminating means for discriminating a shooting scene of the image data based on the index calculated by the index calculating means;
The image processing apparatus according to claim 1, further comprising: The index calculation means calculates a plurality of indexes for specifying the shooting scene,
The scene discrimination means includes
The image processing apparatus according to claim 5, wherein a shooting scene of the image data is determined for each of the plurality of calculated indexes. The index calculating means includes
First index calculation means for calculating a first index that quantitatively indicates that the shooting scene is a flash shooting scene;
Second index calculating means for calculating a second index quantitatively indicating that the shooting scene is a backlight scene;
Third index calculating means for calculating a third index quantitatively indicating that the shooting scene is a person shooting scene;
Have
The scene discrimination means includes
The image processing apparatus according to claim 6, wherein a shooting scene of the image data is determined based on the first index, the second index, and the third index. In an image processing method for color-converting and outputting image data based on color conversion definition data,
A determination step of determining a shooting scene by performing a scene determination process on the image data;
A calculation step of calculating a correction ratio based on the shooting scene determined in the determination step;
A correction step of adding correction according to the shooting scene with respect to the color reproduction characteristics of the color conversion definition data to a degree based on the correction ratio;
A color conversion step of color-converting the image data based on the color conversion definition data corrected in the correction step;
An image processing method comprising: The correction step includes
The specified color conversion definition data by causing the color reproduction characteristics of the color conversion definition data corresponding to the shooting scene to act on the color reproduction characteristics of the color conversion definition data specified in advance to a degree based on the correction ratio. The image processing method according to claim 8, wherein the color reproduction characteristics of the image are corrected. The correction step includes
When the constituent requirements of the subject of the shooting scene determined in the determination step are different from a predetermined reference scene, correction is performed by applying color conversion definition data having a high hue compression rate to the specified color conversion definition data. The image processing method according to claim 9, wherein: The correction step includes
When the luminance configuration of the photographic scene determined in the determination step is different from a predetermined reference scene, correction is performed by causing color conversion definition data having a high saturation compression rate to act on the specified color conversion definition data. The image processing method according to claim 9 or 10. The discrimination step includes
An occupancy ratio calculating step of dividing the image data into an area composed of a combination of predetermined brightness and hue, and calculating the ratio of the divided area in the entire image data as an occupancy ratio for each area;
An index calculation step of calculating an index for identifying a shooting scene by multiplying the occupation rate for each area calculated in the occupation rate calculation step by a coefficient set in advance according to the shooting conditions;
A scene determination step of determining a shooting scene of the image data based on the index calculated in the index calculation step;
The image processing method according to claim 8, comprising: The index calculating step calculates a plurality of indices for specifying the shooting scene,
The scene discrimination step includes
The image processing method according to claim 12, wherein a shooting scene of the image data is determined for each of the plurality of calculated indexes. The index calculation step includes
A first index calculating step for calculating a first index quantitatively indicating that the shooting scene is a flash shooting scene;
A second index calculating step for calculating a second index quantitatively indicating that the shooting scene is a backlight scene;
A third index calculating step of calculating a third index quantitatively indicating that the shooting scene is a person shooting scene;
Have
The scene discrimination step includes
The image processing method according to claim 12 or 13, wherein a shooting scene of the image data is determined based on the first index, the second index, and the third index. Computer
Discriminating means for discriminating a shooting scene by performing scene discrimination processing on image data,
Calculating means for calculating a correction ratio based on the photographic scene determined by the determining means;
Correction means for adding correction according to the shooting scene to the color reproduction characteristics of the color conversion definition data used for color conversion of the image data in a degree based on the correction ratio,
Color conversion means for color-converting the image data based on the color conversion definition data corrected by the correction means;
Image processing program to function as Further function as storage means for storing a plurality of color conversion definition data having different color reproduction characteristics,
The correction means includes
The specified color conversion definition data by causing the color reproduction characteristics of the color conversion definition data corresponding to the shooting scene to act on the color reproduction characteristics of the color conversion definition data specified in advance to a degree based on the correction ratio. The image processing program according to claim 15, wherein the color reproduction characteristic is corrected. The correction means includes
When the constituent requirements of the subject of the photographic scene determined by the determining means are different from a predetermined reference scene, correction is performed by applying color conversion definition data having a high hue compression ratio to the specified color conversion definition data. The image processing program according to claim 16, wherein The correction means includes
When the luminance configuration of the photographic scene determined by the determining unit is different from a predetermined reference scene, correction is performed by applying color conversion definition data having a high saturation compression rate to the specified color conversion definition data. The image processing program according to claim 16 or 17. The discrimination means includes
An occupancy ratio calculating unit that divides the image data into an area composed of a combination of predetermined brightness and hue, and calculates, for each area, the ratio of the divided area to the entire image data as an occupancy ratio;
An index calculation means for calculating an index for specifying a shooting scene by multiplying the occupation ratio for each area calculated by the occupation ratio calculation means by a coefficient set in advance according to shooting conditions;
Scene discriminating means for discriminating a shooting scene of the image data based on the index calculated by the index calculating means;
The image processing program according to claim 15, further comprising: The index calculation means calculates a plurality of indexes for specifying the shooting scene,
The scene discrimination means includes
The image processing program according to claim 19, wherein a shooting scene of the image data is determined for each of the plurality of calculated indexes. The index calculating means includes
First index calculation means for calculating a first index that quantitatively indicates that the shooting scene is a flash shooting scene;
Second index calculating means for calculating a second index quantitatively indicating that the shooting scene is a backlight scene;
Third index calculating means for calculating a third index quantitatively indicating that the shooting scene is a person shooting scene;
Have
The scene discrimination means includes
The image processing program according to claim 19 or 20, wherein a shooting scene of the image data is determined based on the first index, the second index, and the third index.

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