JP2006186898A - Image processing device and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an image processing device and an image processing method, wherein the contrast of an input image is properly and quickly adjusted for each hue. <P>SOLUTION: A CPU 21 selects, first of all, a three-dimensional lookup table (3D-LUT) corresponding to the hue of the image data that are subjected to contrast conversion processing from a 3D-LUT group 230 when the input image inputted through a camera I/F unit 26 is subjected to contrast conversion processing. For instance, when data on images showing a color gamut of complexion are subjected to contrast conversion processing, 3D-LUT of complexion is selected. The input L* value of image data is converted to an output L* value resting on the selected 3D-LUT. A 3D-LUT is selected corresponding to the hue of a color gamut possessed by an input image, and the image data subjected to contrast conversion processing are outputted to a printer through a printer I/F unit 27. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image processing apparatus and an image processing method for performing contrast conversion on an input image and outputting the result.

  2. Description of the Related Art Conventionally, image processing apparatuses that perform various kinds of image processing on image data (hereinafter referred to as “input images”) input from an image input apparatus such as a digital camera or an image reading apparatus and output the image data to a monitor or a printer are known. . Image processing devices generally aim to reproduce the color and gradation of the subject accurately and faithfully, but in this case, the image processing may be sober or the overall impression may be dark. is there.

  For this reason, for example, an ID photo, which is often used for public purposes, is different from a snap photo or the like, under conditions in which the distance to the subject, light distribution, light quantity, illuminance, etc. are properly managed in advance. In addition, the image is taken by a camera with optimized shooting conditions. By stably managing the ID photograph shooting environment in this way, the image processing apparatus can faithfully reproduce the color and gradation of the subject using a fixed color conversion table.

In addition, by using the technique disclosed in Patent Document 1, a desired color region is separated from a color image, and image processing is performed for each separated color region, so that colors and gradations can be reproduced accurately and faithfully. .
JP-A-8-221567

  In this way, for example, an image obtained by photographing a person with a gray background color is subjected to a color conversion process so that the background color gray is not uneven or colored, and the skin tone color of the person is good. Color conversion processing can be performed so as to achieve color reproduction.

  However, for example, when contrast conversion processing (hereinafter referred to as “contrast conversion”) is performed so as to increase the lightness of the skin color in the ID photo, the conversion processing is also applied to the background color gray and the primary color of the subject clothing. In other words, the conversion process is applied to a color gamut other than the hue gamut to be subjected to contrast conversion, and the color of the color gamut is changed.

  In addition, for example, the skin color of the face image of the ID photo and the color of the clothing are affected by the background color, and the contrast of the chromatic color is not adjacent to the human eye so that the skin color and the color of the clothing appear dark in human vision. In some cases, the color was affected by the color gamut.

  In view of this, a method of separating the input image into color gamuts for each hue and changing the contrast in each color gamut using the method of Patent Document 1 can be considered. However, the process of separating the color gamut for each hue is very complicated. For this reason, the processing time has become enormous in proportion to the number of hues in the color gamut in the input image.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to realize an image processing apparatus and an image processing method capable of adjusting the contrast of an input image appropriately and at high speed for each hue. It is.

In order to solve the above problems, an image processing apparatus according to claim 1 is provided.
Achromatic color conversion means for performing contrast conversion on the achromatic color gamut in the input image;
Chromatic color conversion means for performing contrast conversion on a chromatic color gamut in the input image;
With
The contrast conversion gradation characteristic of the achromatic color conversion means is different from the contrast conversion gradation characteristic of the chromatic color conversion means.

The invention according to claim 2 is the image processing apparatus according to claim 1,
The chromatic color conversion means includes
Hue conversion means for performing contrast conversion for each color gamut for each hue of the chromatic color,
The tone conversion characteristic for each hue of the hue conversion means is different.

Invention of Claim 3 is an image processing apparatus of Claim 1 or 2, Comprising:
The chromatic color conversion means includes
A main hue conversion unit that performs contrast conversion on a color gamut of each main hue in the input image;
The main hue conversion means is characterized in that the gradation characteristics of contrast conversion for each main hue are different.

Invention of Claim 4 is an image processing apparatus as described in any one of Claims 1-3, Comprising:
The chromatic color conversion means includes
Primary color conversion means for performing contrast conversion on the gamut of the primary color hue in the input image;
Skin color conversion means for performing contrast conversion on the color gamut of the skin color system hue in the input image;
Have
The primary color conversion means and the skin color conversion means have different contrast conversion gradation characteristics.

Invention of Claim 5 is an image processing apparatus as described in any one of Claims 1-4, Comprising:
In the gamut of achromatic and chromatic colors of the same brightness in the input image,
The brightness after the conversion by the achromatic color conversion means is smaller than the brightness after the conversion by the chromatic color conversion means.

The invention according to claim 6 is the image processing apparatus according to claim 4,
In the color gamut of the same lightness achromatic and skin color system in the input image,
The brightness after the conversion by the achromatic color conversion means is smaller than the brightness after the conversion by the skin color conversion means.

Invention of Claim 7 is an image processing apparatus as described in any one of Claims 1-6,
The contrast conversion is performed using a color conversion table corresponding to a hue of a color gamut to be converted.

The image processing method according to claim 8 comprises:
An achromatic color conversion step for performing contrast conversion on an achromatic color gamut in the input image;
A chromatic color conversion step of performing contrast conversion on a chromatic color gamut in the input image;
Including
The contrast conversion gradation characteristic in the achromatic color conversion step is different from the gradation characteristic in contrast conversion in the chromatic color conversion step.

  According to the first and eighth aspects of the present invention, since the gradation characteristic of contrast conversion for the achromatic color gamut and the gradation characteristic of contrast conversion for the chromatic color gamut are different, the achromatic color and the chromatic color respectively. The color gamut contrast can be adjusted appropriately. For this reason, for example, the contrast of the color of the person's skin can be enhanced in advance with respect to the achromatic background color in the ID photo. Therefore, it is possible to prevent the skin color from being dark and reflected in human vision due to the influence of the background color.

  According to the second aspect of the present invention, the same effect as that of the first aspect of the invention can be obtained, and since the gradation characteristics of the contrast conversion for each hue of the chromatic color are different, the chromatic color Appropriate contrast can be adjusted for each hue. Therefore, for example, in the ID photo, the contrast of the color of clothes as well as the color of the person's skin can be individually adjusted.

  According to the third aspect of the invention, it is of course possible to obtain the same effect as that of the first or second aspect of the invention, and since the gradation characteristics of contrast conversion for each main hue are different, each main hue is different. The contrast can be adjusted appropriately. For this reason, for example, the contrast can be adjusted for each hue of yellow, red, green, and blue in the CIE L * a * b * color system.

  According to the invention described in claim 4, it is needless to say that the same effect as in the invention described in any one of claims 1 to 3 can be obtained, contrast conversion for the primary color gamut, and skin color system. Since the respective tone characteristics of the contrast conversion for the color gamut are different, the contrast of the primary color gamut and the skin color gamut can be adjusted appropriately. For this reason, for example, in the ID photo, the contrast between the color of clothes and the color of the skin of the person can be adjusted appropriately.

  According to the fifth aspect of the present invention, the same effect as that of the first to fourth aspects of the present invention can be obtained. After the contrast conversion of the achromatic and chromatic input images of the same brightness, there is no effect. The lightness of the chromatic color gamut is smaller than the lightness of the chromatic color gamut. Therefore, the contrast of the chromatic color gamut can be enhanced with respect to the achromatic color gamut.

  According to the invention described in claim 6, it is possible to obtain the same effect as that of the invention described in claim 4. After the contrast conversion of the achromatic and skin-colored input images having the same brightness, the achromatic color is converted. The lightness of the color gamut is smaller than the lightness of the flesh-colored color gamut. Therefore, the contrast of the skin color gamut can be enhanced with respect to the achromatic color gamut.

  According to the seventh aspect of the present invention, it is possible to obtain the same effect as the first aspect of the present invention, corresponding to the hue of the color gamut targeted for contrast conversion. Since this conversion is performed using the color conversion table, it is not necessary to perform complicated processing such as dividing the color gamut for each hue and then performing contrast conversion on the divided color gamut. Accordingly, it is possible to increase the speed of contrast conversion for each hue.

Embodiment
DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of an illumination photograph box that applies an image processing apparatus of the present invention to a control apparatus and includes the control apparatus will be described in detail with reference to FIGS.

  FIG. 1 is an example of an overview of the ID photo box 100. As shown in the figure, the ID photo box 100 is formed in a box shape, and an outer wall 17 is provided with an outlet 17a for taking out the ID photo taken. A chair C for the subject M is installed inside the box (hereinafter referred to as a photographing room) so as to be able to be moved up and down, and a display device 15 for displaying an operation procedure and other guide images related to photographing on the front of the subject M, An input device 14 for inputting operation instructions, a detection sensor 13 for detecting that the subject M has entered the photographing room, and a cashier 23 for adjusting the photographing fee are installed. In addition, lighting strobes 24a to 24f are installed on the inner wall of the photographing room above, on the front, on the back, and below the subject M, respectively.

  FIG. 2 is a block diagram showing an outline of the main configuration of the ID photo box 100. As shown in the figure, the ID photo box 100 includes a camera 1, a control device 2, and a printer 3.

  The camera 1 shoots based on an instruction from the control device 2 and outputs human image data (R, G, B data, hereinafter simply referred to as image data) of the photographed subject M to the control device. The control device 2 controls photographing by the camera 1, performs various image processing on the image data (input image) input from the camera 1, and outputs the processed image data to the printer 3.

  The printer 3 forms an image according to the image data after the image processing of the control device 2 on a recording medium (for example, recording paper or film). As a printing method of the printer 3, a sublimation type transfer method in which an image is formed by sublimating and transferring a color material will be described. However, by applying heat by superimposing a recording medium and an image receiving material. A melt transfer recording method in which an image is formed by transferring a recording layer of a recording medium to an image receiving layer of an image receiving material may be applied, or an electrophotographic method, an inkjet method, or other printing methods may be used. Moreover, a silver salt photographic image may be formed.

  FIG. 3 is a block diagram illustrating an example of the internal configuration of the control device 2. As shown in the figure, the control device 2 includes a CPU (Central Processing Unit) 21, a RAM (Random Access Memory) 22, a ROM (Read Only Memory) 23, an input unit 24, a display unit 25, and a camera I / F unit 26. The printer I / F unit 27 is connected to a bus 28.

  The CPU 21 performs an instruction to each functional unit of the control device 2 and input / output of data. Specifically, a program stored in the ROM 23 is read out and expanded in the RAM 22 to execute processing according to the program and control each functional unit of the control device 2.

  The RAM 22 is a storage area that temporarily holds various programs executed by the CPU 21 and data related to these programs.

  The ROM 23 stores data and programs (for example, a program for realizing the processing of the flowchart in FIG. 4) for realizing various functions related to the operation of the control device 2. According to FIG. 3, the ROM 23 stores a three-dimensional lookup table (3D-LUT) group 230 to be described. The 3D-LUT group 230 implements achromatic color conversion means, chromatic color conversion means, hue-specific conversion means, and the like.

  The input unit 24 includes a keyboard and a pointing device such as a mouse having a cursor key, a numeric keypad, and various function keys, and outputs a key pressing signal pressed by the user, a mouse position signal, and the like to the CPU 21. The input unit 24 corresponds to the input device 14 shown in FIG.

  The display unit 25 is configured by a CRT (Cathode-ray Tube), an LCD (Liquid Crystal Display), or the like, and displays and outputs various screens based on display data input from the CPU 21. The display unit 25 corresponds to the display device 15 of FIG.

  The camera I / F unit 26 is an interface for inputting / outputting data with the camera 1, and the printer I / F unit 27 is an interface for inputting / outputting data with the printer 3. The camera I / F unit 26 and the printer I / F unit 27 are configured by, for example, a serial interface such as RS232C, a parallel interface such as Centronics, USB, or the like.

  FIG. 4 is a flowchart illustrating an example of a specific operation of the control device 2. According to the figure, the CPU 21 first performs image processing such as sharpness adjustment and noise removal on the input image input from the camera 1 via the camera I / F unit (step S1). In step S1, various types of image processing such as gray balance adjustment processing, spatial filter processing, and enlargement / reduction processing may be appropriately performed.

  Next, the 3D-LUT group 230 stored in the ROM 23 is read, and contrast conversion is performed using the 3D-LUT group 230 (step S3). The CPU 21 performs output correction processing (for example, gamma correction processing, pixel number change, etc.) on the image data after contrast conversion (for example, step S5), and then performs image processing via the printer I / F unit 27. The image data is output to the printer 3.

  Next, contrast conversion using the 3D-LUT group 230 in step S3 will be described. The 3D-LUT is a color conversion table that stores the brightness of an input image (input brightness) and the brightness (output brightness) of image data after contrast conversion (output) in association with each other. The ROM 23 collects 3D-LUTs having different gradation characteristics for each hue in the L * a * b * color system defined by the CIE (International Lighting Commission) and stores them as a 3D-LUT group 230. .

  The CPU 21 selects a 3D-LUT corresponding to the hue of the image area to be subjected to contrast conversion in the input image from the 3D-LUT group 230, and converts the image area using the selected 3D-LUT. Thus, the contrast of the input image input from the camera 1 is converted into a preferable contrast.

  FIG. 5 shows the L * a * b * color system defined by the CIE. In the figure, L * represents lightness and is designated by a value of 0 to 100%, and becomes brighter as the numerical value is larger. a * and b * represent chromaticity. a * represents a mixing ratio of two colors of green and red, and red becomes stronger as it goes in the + direction, and green becomes stronger as it goes in the-direction. b * represents a mixing ratio of two colors of blue and yellow. Yellow is stronger as it is in the + direction, and blue is stronger as it is in the-direction.

  FIG. 6 shows a skin color system (red-yellow system) color gamut in the L * a * b * color system. The skin gamut color gamut is represented by an elliptical EL range that extends in the upper right direction by approximately 45 ° from the origin in the color gamut including the range R of 5 ≦ a * ≦ 25 and 5 ≦ b * ≦ 25 in FIG. Is done.

  For example, when the color of the elliptical EL color gamut is adjacent to the gray color gamut GR or the color of the blue color gamut BL shown in FIG. Generally, it appears dark in human vision. For example, in the ID photo, when the background color is gray or blue, the color of the human face or clothes surrounded by the background color is affected (pulled) and darkened by the background color. . As described above, when the image data captured by the camera 1 is faithfully reproduced as it is and an image is formed by the printer 3, the brightness of the chromatic color is lowered due to the influence of the adjacent color gamut.

  Therefore, by contrast-converting the input image for each hue using the 3D-LUT group 230 in step S3 in FIG. 4, contrast such as skin color and clothes color is enhanced.

  FIG. 7 is a diagram illustrating an example of the gradation characteristic L1 of the flesh color 3D-LUT 230a. In this figure, the horizontal axis represents the lightness (input L * value) of the input image data of flesh-colored hue, and the vertical axis represents the lightness (output L * value) of the converted (output) data. The reference characteristic L0 represents the gradation characteristic of the input L * value and the output L * value when the brightness of the input image is faithfully reproduced.

  As shown in the figure, the 3D-LUT 230a has gradation characteristics L1 set so that the input L * value <the output L * value as a whole. More specifically, the gradation characteristic L1 is set so that the contrast in the medium / high brightness region (60 ≦ input L * value ≦ 80) is maximized (set up). By performing the contrast conversion using the 3D-LUT 230a, it is possible to output the gamut of the flesh color hue with higher brightness than when the input image is faithfully reproduced. And skin color conversion means is realized. For this reason, for example, in an ID photo taken with a gray or blue background color, it is possible to prevent a human face image from being darkly seen by the naked eye due to the background color.

  FIG. 8 is a diagram illustrating an example of the gradation characteristic L2 of the gray 3D-LUT 230b. According to the figure, the gradation characteristic L2 is substantially the same as the reference characteristic L0. That is, by performing the contrast conversion using the 3D-LUT 230b, the gray-colored achromatic input image is reproduced with the original lightness, thereby realizing an achromatic color conversion means.

  The setting method of the tone characteristic L1 of the 3D-LUT 230a having a flesh-colored hue and the tone characteristic L2 of the 3D-LUT 230b having a gray-colored hue is as follows. The contrast of the color gamut of the system can be enhanced moderately. That is, when the input L * value is in the range of 60 to 80, the gray output L * value is made smaller than the skin color output L * value, and the skin color output L * value and the gray output L * are set. * The difference ΔL * (output L * value difference) from the value is set to a value of about 5-10.

  FIG. 9 is a diagram illustrating an example of the gradation characteristic L3 of the blue 3D-LUT 230c. According to the figure, the 3D-LUT 230c is set so that the output L * value is lower than the entire input L * value, that is, the output is lowered with respect to the original input image.

  FIG. 10 is a diagram illustrating an example of the gradation characteristic L4 of the green 3D-LUT 230d. According to the figure, in the 3D-LUT 230d, the gradation characteristic L4 is set so that the input L * value <the output L * value when the input L * value is 0 to 80. In the range of * values, the contrast ratio of the output L * value to the input L * value is set to be high. The 3D-LUTs 230c and 230d and the CPU 21 cooperate to realize a main hue conversion unit and a primary color conversion unit. Note that the hue to be subjected to contrast conversion by the main hue conversion means and the primary color conversion means is not limited to blue and green, and can be applied as appropriate, for example, yellow or magenta.

  In this way, by performing contrast conversion using a 3D-LUT having different gradation characteristics for each hue, the contrast can be increased or decreased for each hue.

  FIG. 11 is a diagram illustrating the relationship between the input L * value of each hue having the same L * value and the output L * value with respect to the input L * value when contrast conversion is performed using the 3D-LUT group 230. . In the figure, the output L * value is represented by the length from the origin, and the hue is represented in a radial direction from the origin.

  In the figure, as the same brightness in the input image, the output L * value when the input L * value for each color gamut is “20” is represented by the contour line CT20. Similarly, the input L * value is “40”, “ The output L * values for 60 "and" 80 "are represented by contour lines CT40, CT60 and CT80, respectively.

  For example, the contour line CT20 represents that the contrast of the flesh color system and the green color gamut is increased and the contrast of the red blue system color gamut is decreased while the input L * value is “20”. Yes. Further, since the output L * value of the flesh color gamut increases as the input L * value increases, the brightness of the flesh color gamut is emphasized. On the other hand, the blue hue has a lower output L * value than the input L * value in the entire range of “20 to 80”.

  Therefore, when image data having the same lightness in the hue gamuts of each hue is input, the contrast can be adjusted by darkening the blue color gamut and brightening the skin color system and the green color gamut. For this reason, for example, in an identification photograph with a background color of gray or blue, the influence of contrast due to the background color can be suppressed by increasing the skin color of the face and the lightness of the green color of the clothes in advance.

  FIG. 12 shows the result of visual evaluation of a real image of an ID photo of five researchers (evaluators A to E) engaged in image processing development. The evaluation was carried out by a three-level evaluation in which “◯” was “very good”, “Δ” was “ordinary, good”, and “×” was “bad”.

  Further, the ID photo to be evaluated is a sublimation type in which a face image of a person is taken in an ID photo box, and after contrast conversion is performed on the obtained image data, an image is formed by sublimation and transfer of color materials. Output with a transfer printer.

  At the time of contrast conversion, the difference ΔL * of the output L * value between the skin color system and the gray system having the same brightness with the input L * value “60” and the same brightness with the input L * value “80”. Each of the output L * value difference ΔL * between the skin color system and the gray system is set in a combination as in the first to fifth patterns in FIG. Further, when there is no person who evaluates as “x” among the five evaluators, it is determined that a favorable result with clear contrast between the person's skin color and the gray background is obtained.

  As shown in the figure, in the first pattern, when ΔL * at input L * value = 60 is set to “10.5” and ΔL * at input L * value = 80 is set to “11.7”, that is, If the lightness of the gray system after contrast conversion is lower than the lightness of the skin color system, it can be verified that 3 evaluators have evaluated “○” and 2 have “△”, and that a favorable illumination photograph can be obtained. It was.

  Further, in the second pattern, when ΔL * at the input L * value = 60 is set to “5.3” and ΔL * at the input L * value = 80 is set to “7.2”, the two evaluators are “○ "Three people evaluated as" △ ", and it was verified that a favorable illumination photograph was obtained.

  In the third pattern, when ΔL * at input L * value = 60 is set to “0.8” and ΔL * at input L * value = 80 is set to “−1.1”, that is, after contrast conversion. If the lightness of the gray system is substantially the same as the lightness of the skin color system, one evaluator evaluates as “◯”, two evaluate as “△”, and two evaluate as “×”. Obtained.

  In the fourth pattern, when ΔL * at the input L * value = 60 is set to “−3.2” and ΔL * at the input L * value = 80 is set to “−2.9”, that is, after contrast conversion. If the lightness of the gray system is higher than the lightness of the skin color system, two evaluators rated “△” and three evaluated “×”. It was dark and visible to the naked eye, and an undesirable illumination photograph was obtained. Moreover, in the 5th pattern, all the evaluators evaluated it as "x", and it was an unpreferable ID photograph.

  In this way, by setting ΔL * to 5 to 10 for input images having the same input L * value, it was possible to obtain an ID photo having an appropriate contrast for human vision.

  In addition, the gray-scale brightness after contrast conversion is not only made smaller than the flesh-color brightness, but, for example, the gray-scale brightness is converted to contrast conversion of other chromatic colors such as red, blue, and yellow. It goes without saying that the same effect can be obtained by making it smaller than the later brightness.

  As described above, according to the present embodiment, when performing the contrast conversion of the input image, the 3D-LUT corresponding to the hue of the color gamut of the image data to be converted among the 3D-LUT having different gradation characteristics for each hue. And the contrast conversion is performed using the selected 3D-LUT. Thereby, the contrast of the color gamut in the input image can be individually adjusted for each hue. Further, the contrast conversion may be performed using a 3D-LUT corresponding to the hue of the color gamut to be subjected to contrast conversion, and it is not necessary to extract and separate the color gamut in the image data. Therefore, the contrast conversion for each hue can be processed at high speed.

  In this embodiment, the image processing apparatus is applied to the control apparatus 2 of the ID photo box 100. However, the image processing apparatus may be applied to an image reading apparatus such as a digital camera or a scanner. For example, when applied to a digital camera, contrast conversion may be performed to increase the contrast of the color of a person's face or clothes, as described above, or the color of a mountain with respect to the sky blue or the flower with respect to the green of the meadow The contrast conversion target may be appropriately changed according to the hue of the adjacent color gamut so as to increase the contrast of the color and the moon and star colors with respect to the night sky.

  Further, the gradation characteristics of contrast conversion for each hue are not limited to the gradation characteristics as shown in FIGS. That is, when the input image is a landscape image, the gradation characteristics of the 3D-LUT 230a in FIG. 7 may be set so as to reduce the contrast of the skin color system, or the input is based on blue such as the sea or sky. In the case of an image, the gradation characteristics of the 3D-LUT 230c in FIG. 9 may be set so as to increase the blue contrast.

  In addition, the image processing apparatus of the present invention is applied to the control apparatus 2, but may be applied to a control unit of the camera 1, for example. Since the image data input to the control device 2 is digital data and the data is a discrete numerical value, when analog data is A / D converted into digital data, a part of the information is lost or the information Will lose its accuracy. Therefore, before the A / D conversion of the image data captured by the camera 1, the contrast adjustment accuracy similar to that of the present embodiment is performed on the analog image data, thereby improving the contrast adjustment accuracy. .

An example of the general-view figure of the illumination photography box in this embodiment. The block diagram which shows an example of the outline of the main structures of an ID photograph box. The block diagram which shows an example of a function structure of the control apparatus to which this invention is applied. The flowchart for demonstrating the basic operation | movement of a control apparatus. The figure showing the L * a * b * color system of CIE. The figure which shows the color gamut of the skin color type | system | group in a L * a * b * color system, a gray type | system | group, and a blue type | system | group. The figure which shows an example of the gradation characteristic of the three-dimensional look-up table of a skin color type | system | group. The figure which shows an example of the gradation characteristic of a three-dimensional lookup table of a gray type | system | group. The figure which shows an example of the gradation characteristic of a blue-type three-dimensional lookup table. The figure which shows an example of the gradation characteristic of a three-dimensional green look-up table. The figure showing an example of the relationship between the input L * value and output L * value for every hue. The figure which shows the visual evaluation result of the real photograph image of ID photo.

Explanation of symbols

100 ID Photo Box 1 Camera 2 Control Device
21 CPU
22 RAM
23 ROM
230 3D lookup table group
24 Input section
25 Display section
26 I / F part for camera
27 Printer I / F section
28 Bus 3 Printer

Claims (8)

Achromatic color conversion means for performing contrast conversion on the achromatic color gamut in the input image;
Chromatic color conversion means for performing contrast conversion on a chromatic color gamut in the input image;
With
An image processing apparatus, wherein the contrast conversion gradation characteristics of the achromatic color conversion means are different from the contrast conversion gradation characteristics of the chromatic color conversion means. The chromatic color conversion means includes
Hue conversion means for performing contrast conversion for each color gamut for each hue of the chromatic color,
The image processing apparatus according to claim 1, wherein gradation characteristics of contrast conversion for each hue of the hue conversion unit are different. The chromatic color conversion means includes
A main hue conversion unit that performs contrast conversion on a color gamut of each main hue in the input image;
The image processing apparatus according to claim 1, wherein the gradation characteristics of contrast conversion for each main hue of the main hue conversion unit are different. The chromatic color conversion means includes
Primary color conversion means for performing contrast conversion on the gamut of the primary color hue in the input image;
Skin color conversion means for performing contrast conversion on the color gamut of the skin color system hue in the input image;
Have
The image processing apparatus according to claim 1, wherein gradation characteristics of contrast conversion are different between the primary color conversion unit and the skin color conversion unit. In the gamut of achromatic and chromatic colors of the same brightness in the input image,
The image processing apparatus according to any one of claims 1 to 4, wherein the brightness after conversion by the achromatic color conversion means is smaller than the brightness after conversion by the chromatic color conversion means. In the color gamut of the same lightness achromatic and skin color system in the input image,
5. The image processing apparatus according to claim 4, wherein the brightness after conversion by the achromatic color conversion means is smaller than the brightness after conversion by the skin color conversion means.   The image processing apparatus according to claim 1, wherein the contrast conversion is performed using a color conversion table corresponding to a hue of a color gamut to be converted. An achromatic color conversion step for performing contrast conversion on an achromatic color gamut in the input image;
A chromatic color conversion step of performing contrast conversion on a chromatic color gamut in the input image;
Including
An image processing method, wherein a gradation characteristic of contrast conversion in the achromatic color conversion step is different from a gradation characteristic of contrast conversion in the chromatic color conversion step.

Images