Image processing apparatus, method, and program

Abstract

To provide an image processing apparatus that appropriately executes settings of a color conversion method and application of the set color conversion method to image data.SOLUTION: An image processing apparatus comprises: area setting means that sets, on an image represented by input image data, a first area used for settings of a color conversion method for image data, and a second area not used for the settings of the color conversion method; color conversion method setting means that, when the first area and the second area are included on the image as a result of the settings performed by the area setting means, sets the color conversion method on the basis of the image data of the first area set by the area setting means; and generation means that determines the color conversion method set by the color conversion setting means, as a color conversion method to be applied to an area including the first area and at least part of the second area on the image, and generates image data after the color conversion by using the determined color conversion method.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an image processing apparatus, method, and program capable of performing gamma mapping.

Background Art

[0002] There is known a printer that receives a digital manuscript described in a predetermined color space, performs mapping of each color in the color space to a color reproduction range reproducible by a printer, and outputs the result. For example, there is known a method of identifying an object in a manuscript, performing "colorimetric" mapping on a graphic area, and performing "perceptual" mapping on a photo area. However, it is very difficult to identify an object, and especially when a plurality of objects overlap, the areas are merged and a mapping suitable for the merged object is selected.

[0003] Patent Document 1 describes analyzing manuscript data to be recorded and dividing the manuscript data into a plurality of partial manuscript data. Then, based on the pixel values included in the partial manuscript and the color reproduction range (color gamut) at the time of recording for each partial manuscript data, a color mapping method (color conversion method) to the printing color reproduction range for the partial manuscript is set and color conversion is performed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] If the area for setting the color conversion method coincides with the area to which the set color conversion method is applied, the color conversion method may be set considering unnecessary colors, and as a result, an appropriate color conversion result may not be obtained. Therefore, further improvement is required for setting the color conversion method and applying the set color conversion method to image data.

[0006] An object of the present invention is to provide an image processing apparatus, method, and program that appropriately execute setting of a color conversion method and application of the set color conversion method to image data.

Means for Solving the Problems

[0007] To solve the above problems, an image processing apparatus according to the present invention includes: an area setting unit that sets, on an image represented by input image data, a first area used for setting a color conversion method of the image data and a second area not used for setting the color conversion method; a color conversion method setting unit that sets the color conversion method based on the image data of the first area set by the area setting unit when the first area and the second area are included in the image as a result of the setting by the area setting unit; and a generation unit that determines the color conversion method set by the color conversion method setting unit as a color conversion method to be applied to an area including at least a part of the first area and the second area on the image, and generates image data after color conversion using the determined color conversion method.

Effects of the Invention

[0008] According to the present invention, it is possible to appropriately execute setting of a color conversion method and application of the set color conversion method to image data.

Brief Description of the Drawings

[0009]

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Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and duplicate explanations are omitted.

[0011] [First Embodiment] Regarding the terms used in this embodiment, they are defined in advance as follows.

[0012] (Color Reproduction Range) The color reproduction range refers to the range of reproducible colors in an arbitrary color space, and is also referred to as the color reproduction range, color gamut, or gamut. There is also a color gamut volume as an index representing the size of this color reproduction range. The color gamut volume is the three-dimensional volume in an arbitrary color space. The chromaticity points constituting the color reproduction range may be discrete. For example, a specific color reproduction range may be represented by 729 points on CIE-L*a*b*, and for the points in between, known interpolation operations such as tetrahedral interpolation or cubic interpolation may be used to obtain them. In such a case, the corresponding color gamut volume can be obtained by accumulating the volumes on CIE-L*a*b* such as tetrahedrons or cubes corresponding to the interpolation operation method that constitute the color reproduction range. The color reproduction range and color gamut in this embodiment are not limited to a specific color space, but in this embodiment, the color reproduction range in the CIE-L*a*b* space is described as an example. Similarly, the numerical values of the color reproduction range in this embodiment indicate the volume when calculated cumulatively in the CIE-L*a*b* space on the premise of tetrahedral interpolation.

[0013] (Gamma Mapping) Gamma mapping is a process of converting between different color gamuts. For example, it is to map an input color gamut to an output color gamut. Conversion within the same color gamut is not called gamma mapping. Perceptual, Saturation, Colorimetric, etc. of the ICC (International Color Consortiaum) profile are common. The mapping process may be performed, for example, using one three-dimensional 3DLUT (Look Up Table). Also, after converting to a standard color space, the mapping process may be performed. For example, when the input color space is sRGB, it is converted to the CIE-L*a*b* color space. On the CIE-L*a*b* color space, the mapping process is performed to the output color gamut. The mapping process may be a 3DLUT process or may use a conversion formula. Also, the conversion between the input color space and the output color space may be performed simultaneously. For example, at the input, it is the sRGB color space, and at the output, it may be converted to the RGB values or CMYK values specific to the recording device.

[0014] (Color Degradation) In the present embodiment, for any two colors, when performing gamma mapping, color degradation is defined as the distance between the colors after mapping in a predetermined color space being smaller than the distance between the colors before mapping. Specifically, assume that there are color A and color B in a digital manuscript, and by mapping them to the color gamut of a printer, color A is converted to color C and color B is converted to color D. In this case, color degradation is defined as the distance between color C and color D being smaller than the distance between color A and color B. When color degradation occurs, what was recognized as different colors in the digital manuscript may be recognized as the same color when recording the image. For example, in a graph, different items are recognized as different by using different colors for different items. Due to color degradation occurring, different colors being recognized as the same color may cause the drawback that different items in the graph are misrecognized as the same item. The predetermined color space for calculating the distance between colors here can be any color space. For example, it can be the sRGB color space, Adobe RGB color space, CIE-L*a*b* color space, CIE-LUV color space, XYZ colorimetric system color space, xyY colorimetric system color space, HSV color space, HLS color space, etc.

[0015] <Entire image processing apparatus> FIG. 1 is a block diagram showing the configuration of the image processing apparatus according to the present embodiment. As the image processing apparatus 101, a PC, a tablet, a server, or a recording apparatus is used. The CPU 102 reads a program stored in a storage medium 104 such as an HDD or a ROM into the RAM 103 as a work area and executes various image processes thereby. For example, the CPU 102 acquires a command from a user via an HID (Human Interface Device) I / F (not shown). Then, according to the acquired command and the program stored in the storage medium 104, various image processes are executed. Also, the CPU 102 performs predetermined processing on the document data acquired via the data transfer I / F 106 according to the program stored in the storage medium 104. Then, the result and various information are displayed on a display (not shown) and transmitted via the data transfer I / F 106. The image processing accelerator 105 is hardware capable of executing image processing faster than the CPU 102. The image processing accelerator 105 is activated when the CPU 102 writes parameters and data necessary for image processing to a predetermined address in the RAM 103. After reading the above parameters and data, the image processing accelerator 105 executes image processing on the data. However, the image processing accelerator 105 is not an essential element, and the CPU 102 may execute equivalent processing. Specifically, the image processing accelerator 105 is a GPU or a dedicated electrical circuit. The above parameters may be stored in the storage medium 104 or acquired from the outside via the data transfer I / F 106.

[0016] In the recording device 108, the CPU 111 reads the program stored in the storage medium 113 into the RAM 112 as a work area and executes it, thereby comprehensively controlling the recording device 108. The image processing accelerator 109 is hardware capable of executing image processing faster than the CPU 111. The image processing accelerator 109 is activated when the CPU 111 writes the parameters and data necessary for image processing to a predetermined address in the RAM 112. After reading the above parameters and data, the image processing accelerator 109 executes image processing on the data. However, the image processing accelerator 109 is not an essential element, and the same processing may be executed by the CPU 111. The above parameters may be stored in the storage medium 113 or may be stored in a storage (not shown) such as a flash memory or an HDD.

[0017] Here, the image processing performed by the CPU 111 or the image processing accelerator 109 will be described. The image processing is, for example, a process of generating data indicating the dot formation position of ink in each scan by the recording head 115 based on the acquired recording data. The CPU 111 or the image processing accelerator 109 performs, for example, color conversion processing and quantization processing on the acquired recording data.

[0018] The color conversion processing is a process of color separation into the ink density handled by the recording device 108. For example, the acquired recording data includes image data indicating an image. When the image data is data indicating an image in a color space coordinate such as sRGB which is the display color of the monitor, the data indicating the image in the sRGB color coordinates (R, G, B) is converted into ink data (CMYK) handled by the recording device 108. The color conversion method is realized by matrix operation processing, three-dimensional lookup table (3DLUT), processing using a four-dimensional 4DLUT, or the like.

[0019] The recording device 108 of the present embodiment uses, as an example, inks of black (K), cyan (C), magenta (M), and yellow (Y). Therefore, the image data of RGB signals is converted into image data (ink data) composed of 8-bit color signals of K, C, M, and Y. The color signal of each color corresponds to the amount of application of each ink. Further, although four colors of K, C, M, and Y are cited as examples of the number of ink colors, other ink colors such as light cyan (Lc), light magenta (Lm), and gray (Gy) inks with low density may be used to improve the image quality. In that case, ink data corresponding thereto is generated.

[0020] After the color conversion process, quantization processing is performed on the ink data. The quantization process is a process of reducing the number of gradation levels of the ink data. In the present embodiment, quantization is performed using a dither matrix in which thresholds for comparing with the values of the ink data are arranged for each pixel. Through the quantization process, finally, binary data indicating whether to form dots or not at each dot formation position is generated.

[0021] After the image processing is performed, the binary data is transferred to the recording head 115 by the recording head controller 114. At the same time, the CPU 111 performs recording control so as to operate the carriage motor that operates the recording head 115 via the recording head controller 114, and further operate the conveyance motor that conveys the recording medium. The recording head 115 scans the recording medium, and at the same time, ink droplets are ejected onto the recording medium by the recording head 115, thereby recording an image.

[0022] The image processing apparatus 101 and the recording device 108 are connected via a communication line 107. In the present embodiment, a local area network is described as an example of the communication line 107, but a USB hub, a wireless communication network using a wireless access point, a connection using a Wi-Fi (registered trademark) direct communication function, etc. may also be used. Hereinafter, the recording head 115 will be described as having a recording nozzle array of four-color color inks of cyan (C), magenta (M), yellow (Y), and black (K).

[0023] FIG. 2 is a diagram for explaining the recording head 115 in the present embodiment. In the present embodiment, an image is recorded by performing a plurality of N scans on a unit area corresponding to one nozzle row. The recording head 115 includes a carriage 116, nozzle rows 117, 118, 119, 120, and an optical sensor 122. The carriage 116 equipped with the five nozzle rows 117, 118, 119, 120 and the optical sensor 122 can reciprocate along the main scanning direction (X direction in the figure) by the driving force of a carriage motor transmitted via a belt 121. As the carriage 116 moves relative to the recording medium in the X direction, ink droplets are ejected from each nozzle of the nozzle row in the gravitational direction ( - Z direction in the figure) based on the recording data. In the present embodiment, the ejection element that ejects ink droplets from each nozzle is a thermal method that generates bubbles by an electrothermal conversion element to eject the liquid. However, the present invention is not limited to this, and a piezoelectric element (piezo) may be used to eject the liquid, or other ejection methods may be used for the ejection element.

[0024] As a result, an image corresponding to 1 / N (N: natural number) times of main scanning is recorded on the recording medium placed on the platen 123. When one main scan is completed, the recording medium is conveyed in the conveyance direction (Y direction in the figure) intersecting the main scanning direction by a distance corresponding to the width of 1 / N times of main scanning. By these operations, an image is recorded by performing N scans on an area with a width corresponding to one nozzle row. By alternately repeating such main scanning and conveyance operations, an image is gradually recorded on the recording medium. By doing so, it is possible to control to complete the image recording for a predetermined area.

[0025] <Recording Process> FIG. 3 is a flowchart showing the recording process in the image processing apparatus 101. The process in FIG. 3 is realized, for example, when the CPU 102 executes a program read into the RAM 103. In the present embodiment, an example is shown in which the recording process is performed by the image processing apparatus 101, but it may be performed by the recording apparatus 108, or may be configured to be shared and processed by the image processing apparatus 101 and the recording apparatus 108.

[0026] In S101, the CPU 102 acquires manuscript data to be recorded. Specifically, the CPU 102 acquires the manuscript data from the data transfer interface of the host PC via the data transfer I / F 106 of the image processing apparatus 101. Here, the manuscript data is document data composed of multiple pages.

[0027] Next, in S102, the CPU 102 divides the manuscript data into a plurality of partial manuscript data. In the present embodiment, the manuscript data to be recorded is, for example, document data composed of multiple pages. The partial manuscript data may be in any form as long as it is a processing unit into which the manuscript data is divided. FIG. 4 is a diagram for explaining partial image data. For example, page units such as the image data 200 shown in FIG. 4(a) may be used as the partial manuscript data. FIG. 4(b) shows a recording area recorded by scanning of the recording head 115. The area 204 shows an example in which recording is completed by two scans of the recording head 115 (the arrows indicate the scanning direction). Data in units recorded by the recording head such as the area 204 may be used as the partial manuscript data. Further, when the image data in FIG. 4(a) is described in a page description language (PDL), the area 201 or the area 202, which is a unit area determined by the drawing instruction, may be used as the partial manuscript data. Further, for example, if it is in page units, a plurality of area units determined by pages, bands, and drawing instructions may be combined into one as the partial manuscript data, such as combining the first page and the second page as the partial manuscript data. In the present embodiment, an example of dividing into partial manuscript data in page units is shown.

[0028] Next, in S103, the CPU 102 performs loop processing executed for each partial manuscript data. In S103, the CPU 102 performs color conversion processing on the partial manuscript data. Details of the color conversion processing will be described later.

[0029] Next, in S104, the CPU 102 determines whether the color conversion of all partial manuscript data has been completed. If it is determined that the conversion has been completed, the process proceeds to S105. If it is determined that the conversion has not been completed, the color conversion process of S103 is performed on the next partial manuscript data. Next, in S105, the CPU 102 records the manuscript data. Specifically, for each pixel of the image data converted in S103, four processes of ink color separation, output characteristic conversion, quantization, and recording are performed.

[0030] Ink color separation is a process of converting the output values Rout, Gout, and Bout, which are the output values of the color conversion process, into the output values of each ink color to be recorded by an inkjet recording method. In this embodiment, for example, recording using four colors of ink, cyan, magenta, yellow, and black, is assumed. There are various implementation methods for this conversion. For example, similar to the color conversion process, a 3D LUT is used to calculate a suitable combination of ink color pixel values (C, M, Y, K) for a combination of output pixel values (Rout, Gout, Bout). For example, the following 3D LUT2

[0256]

[0256]

[0256] [4] is used.

[0031] C = LUT2[Rout][Gout][Bout][0] ··· (1) M = LUT2[Rout][Gout][Bout][1] ··· (2) Y = LUT2[Rout][Gout][Bout][2] ··· (3) K = LUT2[Rout][Gout][Bout][3] ··· (4) Also, the number of grid points of the LUT may be reduced from 256 grid points to, for example, 16 grid points, and the table size may be reduced by interpolating the table values of a plurality of grid points to determine the output value.

[0032] Subsequently, the output characteristic conversion is a process of converting the density of each ink color into the rate of recording dots. Specifically, for example, the density of 256 gradations for each color is converted into the rates of recording dots Cout, Mout, Yout, and Kout of 1024 gradations for each color. For this purpose, for example, a one-dimensional LUT3[4]

[0256] with suitable rates of recording dots for the density of each ink color set as follows is used.

[0033] Cout = LUT3[0][C] ··· (5) Mout = LUT3[1][M] ··· (6) Yout = LUT3[2][Y] ··· (7) Kout = LUT3[3][K] ··· (8) Also, the number of grids of the LUT may be reduced from 256 grids to, for example, 16 grids, and the table size may be reduced by interpolating the table values of a plurality of grids to determine the output value.

[0034] Subsequently, quantization is a process of converting the rates of recording dots Cout, Mout, Yout, and Kout of each ink color into the On / Off of the recording dots of each actual pixel. Regarding the quantization method, for example, various methods such as the error diffusion method and the dither method can be used. For example, it is realized by the dither method as follows.

[0035] Cdot = Halftone[Cout][x][y] ··· (9) Mdot = Halftone[Mout][x][y] ··· (10) Ydot = Halftone[Yout][x][y] ··· (11) Kdot = Halftone[Kout][x][y] ··· (12) Then, by comparing with a threshold value corresponding to each pixel position (x, y), the On / Off of the recording dots of each ink color is realized. Here, for example, assume that Cout, Mout, Yout, and Kout are each represented by 10 bits and take values in the range of 0 to 1023. Therefore, the generation probability of each recording dot is Cout / 1023, Mout / 1023, Yout / 1023, and Kout / 1023. Finally, the generated image data is recorded.

[0036] <Color conversion processing> FIG. 5 is a flowchart for explaining the color conversion processing of S103 in FIG. 3 in the first embodiment. The processing in FIG. 5 is realized, for example, when the CPU 102 executes a program read into the RAM 103. In this embodiment, an example is shown where the color conversion processing is performed by the image processing apparatus 101, but it may also be performed by the recording apparatus 108, or may be configured to be processed in cooperation between the image processing apparatus 101 and the recording apparatus 108. In this embodiment, an example is shown of creating a color conversion table that reduces color degradation so that the colors of the original data can be discriminated (identifiable) in the output of the recording apparatus 108.

[0037] In S201, the CPU 102 acquires image data for color conversion processing. The image data acquired in this embodiment is the partial original data output from the aforementioned S102, and is, for example, image data in units of pages. The image data includes color information representing colors defined in a predetermined color space. The color information in this embodiment is sRGB data. The color information is not limited to this, and any type of data may be used as long as colors can be defined, such as Adobe RGB data, CIE-L*a*b* data, CIE-LUV data, XYZ colorimetric system data, xyY colorimetric system data, HSV data, HLS data, etc.

[0038] Next, in S202, the CPU 102 performs color conversion on the image data using a color conversion table stored in advance in the storage medium 104. The color conversion in this embodiment is to perform gamma mapping on the image data, and map the color reproduction range of the sRGB data to the color reproduction range of the recording device 108. The recording device 108 has different color reproduction ranges depending on the recording method, recording speed, etc. determined for each output mode. Therefore, the image processing apparatus 101 requires gamma mapping corresponding to a plurality of output modes. The image data after gamma mapping is stored in the RAM 103 or the storage medium 104. Specifically, the color conversion table is a three-dimensional LUT. With the three-dimensional LUT, it is possible to calculate a combination of output pixel values (Rout, Gout, Bout) for a combination of input pixel values (Rin, Gin, Bin). When Rin, Gin, and Bin, which are input values, each have 256 gradations, it is preferable to use a table LUT1

[0256]

[0256]

[0256] [3] having a total of 16,777,216 sets of output values. The above-described gamma mapping table is used to perform color conversion. Specifically, it can be realized by executing the following formula for each pixel of the image composed of the RGB pixel values of the image data input in S101.

[0039] Rout = LUT1[Rin][Gin][Bin][0]···(13) Gout = LUT1[Rin][Gin][Bin][1]···(14) Bout = LUT1[Rin][Gin][Bin][2]···(15) Also, known techniques for reducing the table size may be used, such as reducing the number of grid points of the LUT from 256 grid points to, for example, 16 grid points, and interpolating the table values of a plurality of grids to determine the output value.

[0040] Next, in S203, the CPU 102 sets a first area used to set the color conversion method of the image data and a second area not used to set the color conversion method of the image data on the image represented by the image data acquired in S201 (area setting). In this embodiment, setting the color conversion method means creating a color conversion table for gamma mapping. The setting of the color conversion method may create a conversion formula or create a color conversion table, and any method may be used as long as a method capable of performing color conversion can be set.

[0041] FIG. 6 shows an example of the image data acquired in S201. FIG. 6(a) is the original manuscript data created for the user to input to the image processing apparatus 101. FIG. 6(b) is an image obtained by first performing resolution conversion on the image data of FIG. 6(a) at a low resolution by simple decimation and then performing resolution conversion again to the original resolution by bilinear conversion. In the image processing apparatus 101, due to the capacity limitation of the storage medium 104 of the image processing apparatus 101, the input manuscript data may be subjected to resolution conversion or compression and stored in the storage medium 104, and then expanded and used when needed. FIG. 6(a) has only two colors, color 601 and color 602, of the bar graph, but in FIG. 6(b), in addition to color 601 and color 602, color 603 and color 604 are generated by the above-mentioned resolution conversion. Generally, when performing resolution conversion from a low resolution to the original resolution as described above, color 603 that occurs unintentionally by the user becomes a color close to color 601, and similarly, color 604 that occurs unintentionally by the user becomes a color close to color 602.

[0042] FIGS. 7(a) to 7(c) are diagrams for explaining color degradation and its improvement. FIG. 7(a) shows the case where the image data before color conversion is FIG. 6(a), and FIGS. 7(b) and 7(c) show the case where the image data before color conversion is FIG. 6(b). The color reproduction area 701 is the color reproduction area of the image data, and in this embodiment, it represents the sRGB color reproduction area. The color reproduction area 702 is the color reproduction area after the color conversion process of S205 described later, and corresponds to the color reproduction area in a predetermined output mode of the recording apparatus 108.

[0043] In FIG. 7(a), color 703 is the color after color-converting color 601 by gamma mapping. Color 704 is the color after color-converting color 602 by gamma mapping. When the color difference ΔE705 between color 703 and color 704 is smaller than the color difference ΔE706 between color 601 and color 602, it is determined that color degradation has occurred. As a method for calculating the color difference ΔE, the Euclidean distance in the color space is used. In the present embodiment, as a preferred example, the Euclidean distance in the CIE-L*a*b* color space (hereinafter referred to as color difference ΔE) will be used for explanation. Since the CIE-L*a*b* color space is a visually uniform color space, the Euclidean distance can be approximated as the amount of color change. Therefore, a person perceives that the colors are approaching when the Euclidean distance on the CIE-L*a*b* color space becomes smaller, and perceives that the colors are separating when it becomes larger. The color information in the CIE-L*a*b* color space is represented by a three-axis color space of L*, a*, and b* respectively. The calculation formula for the color difference ΔE between color (L1, a1, b1) and color (L2, a2, b2) is the following formula. TIFF2025105458000002.tif14113···(16) Therefore, in the present embodiment, a color conversion table is created to correct color degradation by separating the color distance between color 703 and color 704 on a predetermined color space. Specifically, a correction process is performed to increase the color distance so that color 703 and color 704 have a color distance greater than the color distance that can be identified as different colors based on human visual characteristics. Based on visual characteristics, the color distance that can be identified as different colors is such that the color difference ΔE is 2.0 or more. More preferably, it is desirable that the color difference between color 703 and color 704 is about the same as color difference ΔE706. Therefore, a color conversion table is created in which color 601 is gamma-mapped to color 707 and color 602 is gamma-mapped to color 708. As a result, a color difference ΔE709 equal to color difference ΔE706 can be reproduced in the device color gamut.

[0044] On the other hand, in FIGS. 7(b) and 7(c), color 710 is the color after color-converting color 603 by gamma mapping. Color 711 is the color after color-converting color 604 by gamma mapping. If correction is made to increase the color distance to correct color degradation in the same manner as described above, a color conversion table will be created in which color 601 is gamma-mapped to color 712, color 602 is gamma-mapped to color 713, color 603 is gamma-mapped to color 714, and color 604 is gamma-mapped to color 715. Therefore, although a color distance is created, there may be a case where the color difference ΔE716 between color 712 and color 713 becomes 2.0 or more, or the color distance in the device color gamut cannot be increased to the same extent as color difference ΔE706. As a result, there may be a case where colors that can be identified in the original data displayed on the monitor cannot be identified in the output result of the recording device 108.

[0045] In the present embodiment, instead of setting the color conversion method using the color information of all pixels of the image data, a first region used to set the color conversion method of the input image data and a second region not used to set the color conversion method of the input image data are set, and the color conversion method is set using the color information of the first region. As will be described later, in the present embodiment, a region necessary for color discrimination is set from the input image data, and the color conversion table is created limited to the color information of that region. As a result, even when the image data of FIG. 6(b) is input, it becomes possible to set a color conversion method suitable for color discrimination in FIG. 7(a) instead of FIG. 7(c), and it is possible to improve the problem that the color difference cannot be identified in the output of the recording device 108 described above.

[0046] In this embodiment, the color information of the image data that can be identified by a person and discriminated in the output of the recording device 108 is set as a region having a planar area equal to or larger than a predetermined value, and this region is set as the first region. Therefore, a region in which pixels having the same color information in the image data are continuous vertically by two or more pixels and continuous horizontally by two or more pixels is set as the first region. FIG. 8 is a diagram for explaining the setting of the first region in this embodiment. As shown by the arrow in FIG. 8(a), in this embodiment, line processing is performed, and sequential processing is performed on the pixel-by-pixel image data. In the pixel-by-pixel processing, it is determined whether the color information of each of the three surrounding pixels (pixel 801, pixel 802, pixel 803) of the pixel to be processed (target pixel) 800 shown in FIG. 8(b) is the same as the color information of the target pixel. If the determination result is the same, the four pixels including the target pixel are set as the first region. Pixels that have already been set as the first region may be reset as the first region in the pixel-by-pixel processing. In this embodiment, the first region is set using the above-described method, but the method is not limited to the above as long as a region of the same color information having a planar area equal to or larger than a predetermined value can be extracted. Also, in this embodiment, a region having the same color information is extracted, but in the original image data, the same color information may vary within a predetermined range in non-reversible compression image data such as JPEG. Therefore, a range allowing variation may be set, for example, such that the color difference ΔE is within 1.0 or the difference in RGB values is within a predetermined value for a region having the same color information.

[0047] As a result of the setting, in this embodiment, for any of the image data in FIGS. 6(a) and 6(b), the region filled in black in FIG. 9 is set as the first region, and the region filled in white is set as the second region. In other words, even if colors 603 and 604 unintended by the user occur, those colors are not considered for setting the color conversion method of the input image data.

[0048] Next, in S204, the CPU 102 creates a color conversion table based on the following information.

[0049] · The image data acquired in S201 ·The color conversion table stored in the storage medium 104 in advance and used in S202 ·The image data subjected to color conversion using the color conversion table stored in the storage medium 104 in advance in S202 ·The area information set in S203 The format of the color conversion table created in S204 may be the same as the format of the color conversion table stored in the storage medium 104 in advance and used in S202. Next, in S205, the CPU 102 generates the image data after color conversion by performing an operation on the image data acquired in S201 using the color conversion table created in S204. The generated image data is stored in the RAM 103 or the storage medium 104.

[0050] <Setting of the color conversion method> The method for creating a color conversion table that reduces the color degradation in S204 will be described in detail using the flowchart in FIG. 10. The process in FIG. 10 is realized, for example, by the CPU 102 executing the program read into the RAM 103. In the present embodiment, an example is shown in which the process of creating the color conversion table is performed by the image processing apparatus 101, but it may be performed by the recording apparatus 108, or may be a configuration in which the processing is shared between the image processing apparatus 101 and the recording apparatus 108.

[0051] In S301, the CPU 102 detects the color information of the first area in FIG. 9 set in S203. The detection process is repeated for each pixel of the image data in the first area and is performed for all the pixels included in the image data in the first area. In the present embodiment, the colors 601 and 602 in FIG. 6(a) or FIG. 6(b) are detected. Note that the list of color information is initialized at the start of S301.

[0052] In S302, the CPU 102 detects the number of combinations of colors that are color-degraded among the combinations of the color information list based on the color information list detected in S301. Here, as described in S203, the combination of the colors 601 and 602 is detected as being color-degraded.

[0053] In S303, the CPU 102 determines whether the number of combinations of colors that have undergone color degradation in S302 is zero. If it is determined that the number of combinations of colors that have undergone color degradation is zero, the process proceeds to S304, and it is determined that the image does not require color degradation correction. In that case, the color conversion table is set to the color conversion table stored in the pre-stored storage medium 104 used in S202. If it is determined that the number of combinations of colors that have undergone color degradation is not zero, the process proceeds to S305, and the CPU 102 performs color degradation correction.

[0054] The color will change due to color degradation correction. Therefore, color changes will also occur for combinations of colors that have not undergone color degradation, resulting in unnecessary color changes. Therefore, it may be possible to determine the necessity of color degradation correction from the total number of combinations in the color information list and the number of combinations of colors that have undergone color degradation. Specifically, for example, if the number of combinations of colors that have undergone color degradation is more than half of the total number of combinations in the color information list, it may be determined that color degradation correction is necessary (i.e., it is determined in S303 that there is color degradation correction). By doing so, it is possible to suppress the adverse effects of color changes due to color degradation correction. For example, in FIGS. 6(a) and 6(b), bar graphs are shown for two colors, color 601 and color 602. However, if a bar graph of 10 colors is shown, the total number of combinations will be 45. In that case, if the number of combinations of colors that have undergone color degradation is, for example, 23 or more, it may be determined that color degradation correction is necessary.

[0055] In S305, the CPU 102 performs color fade correction on the combination of colors that fade in color based on the image data, the image data after color conversion, and the color conversion table. As described with reference to FIG. 7, color fade correction is performed so that the color difference ΔE705 between color 703 and color 704 becomes equal to the color difference ΔE709 between color 707 and color 708, which is of the same degree as the color difference ΔE706. The correction process for color fade is repeated for the number of combinations of colors that fade. The results of color fade correction for the number of combinations of colors are stored in a table, which holds the color information before correction and the color information after correction. In FIG. 7, the color information is the color information in the CIE-L*a*b* color space. Therefore, it may be converted into the color space of the input image data and the output image data. In that case, the color information before correction in the color space of the input image data and the color information after correction in the color space of the output image data are stored in a table.

[0056] Also, in FIG. 7, it was on the extension line between color 703 and color 704, but in this embodiment, it is not limited to this. As long as the color difference ΔE709 between color 707 and color 708 is separated by the color difference ΔE706, it may be in any direction in the CIE-L*a*b* color space, i.e., the lightness direction, the chroma direction, or the hue angle direction. Also, it may be not only in one direction but also in any combination of the lightness direction, the chroma direction, and the hue angle direction. Further, although FIG. 7 shows an example of correcting both color 703 and color 704, correction may be performed so that the color difference ΔE706 is separated by correcting only one of the colors.

[0057] In S306, the CPU 102 changes the color conversion table using the result of the degeneracy correction in S305. The color conversion table before the change is a table that converts color 601 in FIGS. 6(a) and 6(b) to color 703 and color 602 to color 704. Using the result of S305, it is changed to a table that converts color 601 in FIG. 6(a) to color 707 and color 602 to color 708 (color conversion method setting). On the other hand, if it is determined in S303 that there is no color degeneracy correction, the process of S306 is not performed. That is, in other words, the process of S303 can also be said to be a process of determining whether to change the color conversion table in S306. As described above, a table after color degeneracy correction can be created. The change of the color conversion table is repeated for the number of combinations of colors that degenerate.

[0058] As shown in FIG. 9, in the present embodiment, the color information of the image data that can be identified by a person and discriminated in the output of the recording device 108 is assumed to be a region having a planar area of a predetermined size or more, and the region is set as color 601 and color 602. Therefore, for example, the horizontal line at the bottom of the bar graph in FIG. 6(a) or FIG. 6(b) is not detected and is not a target for setting color degeneracy correction, so it is not necessary to apply the above-created changed color conversion table. Also, when the image data in S201 is FIG. 6(b), as shown in FIG. 9(b), colors 603 and 604 are not the first regions used to generate the correction color conversion table, but are regions (second regions) adjacent to the first region. And as described above, since colors 603 and 604 are colors close to colors 601 and 602, colors 603 and 604 are also color-converted by the above-changed color conversion table. In other words, the region to which the changed color conversion table is applied can be said to be the first region and a region including at least a part of the second region. In this way, by making the region used to generate the changed color conversion table different from the region to which the generated changed color conversion table is applied, unnecessary color degeneracy correction can be prevented and an optimal output image can be obtained.

[0059] According to this embodiment, a first area used to set the color conversion method of the image data and a second area not used to set the color conversion method of the image data are set. By setting each area, unnecessary color degradation correction can be prevented, and an appropriate color conversion method can be set based only on the information of the area (i.e., the first area) necessary for color degradation correction. As a result, a color conversion result suitable for the recording device 108 can be obtained for the entire image.

[0060] In this embodiment, the color information of the image data that can be identified by a person and discriminated in the output of the recording device 108 is set as an area having a predetermined area in a plane, and the pixels having the same color information are continuous vertically by two or more pixels and horizontally by two or more pixels. The first area was set under the condition. However, the number of continuously arranged pixels in the vertical and horizontal directions may be set according to the output resolution of the recording device 108, the visual characteristics of the person who views the output of the recording device 108, and the like. As a result, it becomes possible to set the first area more optimally. Further, the user who uses the recording device 108 may specify the setting conditions of the first area from the user interface (UI) of the recording device 108 or the attached information of the document data. As a result, it becomes possible to reflect the user's intention in the setting conditions of the first area.

[0061] Also, in this embodiment, the color conversion table stored in the storage medium 104 in advance is used for setting the color conversion table, and the color conversion table is created in the same format as the color conversion table. For example, in the color conversion of S202, without using the color conversion table stored in the storage medium 104, the color may be converted according to a predetermined rule so as to convert the color from the color reproduction range of the acquired image data to the color reproduction range of the recording device 108 relatively. As a result, it is not necessary to hold the color conversion table in the storage medium 104 in advance, and the storage capacity can be reduced. Also, in the setting of the color conversion method of S204, the color conversion table may not be set, and the color information before and after the color conversion may be set in a 1:1 correspondence (so-called dictionary format), or may be set by a calculation formula if it can be approximated by a calculation formula. As a result, compared with the color conversion table, the storage capacity for holding the color conversion method can be reduced.

[0062] [Second Embodiment] Hereinafter, a second embodiment will be described with respect to points different from the first embodiment. In the first embodiment, in order to perform appropriate color conversion on image data, a configuration for setting a color conversion method based on information on a first area necessary for color conversion was described. However, when the set color conversion method is applied to the image data, there may be a region where the image quality deteriorates with the set color conversion method.

[0063] FIG. 11 is an example of the image data acquired in S201 in the second embodiment. At the lower part of the image data in FIG. 11, in addition to the image data in FIG. 6(a), a region 1101 and a region 1102 which are horizontal bar graphs are drawn. In both the regions 1101 and 1102 of the bar graph, a horizontal gradation is drawn. For easier explanation, the left end of the region is color 601 in FIG. 6, the right end is color 602, and in between, pixels of a gradation in which the brightness continuously changes between color 601 and color 602 are configured.

[0064] When the color conversion table stored in the storage medium 104 in advance in S202 of the first embodiment is applied to the region 1101 in FIG. 11, a smooth gradation connecting color 601 and color 602 in FIG. 6(a) is output from the recording device 108. On the other hand, when the color conversion table for reducing color degradation created in S306 of the first embodiment is applied to the region 1101 in FIG. 11, a gradation between color 707 and color 708 in FIG. 7(a) is output from the recording device 108. In this case, as shown in FIG. 7(a), although the color reproduction range for reproducing the gradation is expanded, since the number of pixels forming the gradation is the same, the color information of each pixel constituting the gradation becomes more discrete data. Therefore, there may be a step between the gradation levels of the gradation. Thus, for example, when a color conversion table that emphasizes color discrimination (that is, a color conversion table for reducing color degradation) is set, image quality degradation may occur in a region that emphasizes color continuity (gradation).

[0065] Therefore, in the present embodiment, in order to reduce image quality degradation, an example will be described in which an area to which a set color conversion method is applied and an area to which the set color conversion method is not applied are set, and the color conversion method is switched according to the set areas.

[0066] FIG. 12 is a flowchart for explaining the color conversion process of S103 in FIG. 3 in the second embodiment. The process of FIG. 12 is realized, for example, by the CPU 102 executing a program read into the RAM 103. In the present embodiment, an example is shown in which the color conversion process is performed by the image processing apparatus 101, but it may be performed by the recording apparatus 108, or may be configured to be shared and processed by the image processing apparatus 101 and the recording apparatus 108. Since S201 to S203 are the same as those in the first embodiment, their descriptions are omitted. Also, S202 and S203 are executed in parallel with S401. Furthermore, sequential processing may be performed in the order of S201, S401, and S202.

[0067] In S401, the CPU 102 sets a third area to which the color conversion method set in S402 in the subsequent stage is applied and a fourth area to which the color conversion method set in S402 is not applied from the image data acquired in S201. Here, in order to emphasize the color gradation, the area to which the color conversion table that emphasizes color discrimination is not applied is set as the fourth area. That is, the area that emphasizes the color gradation is set as the fourth area.

[0068] In order to emphasize the color gradation in this embodiment, FIG. 8 is used for explanation in the same manner as in the first embodiment to describe the setting of the fourth region where the color conversion table that emphasizes color discrimination is not applied. As shown by the arrow in FIG. 8(a), in line processing, sequential processing is performed on the image data in pixel units. In the pixel unit processing, as shown in FIG. 8(b), it is determined whether the color information of the three pixels (pixel 801, pixel 802, pixel 803) around the target pixel (the pixel to be processed) 800 is continuous with the color information of the target pixel. In this embodiment, if the color information of each of the three pixels around the target pixel 800 is not the same as the color information of the target pixel 800 and is not separated by 2.0 or more in color difference ΔE, the target pixel is set as the fourth region. A pixel that has already been set as the fourth region may be reset as the fourth region in the pixel unit processing. In this embodiment, the fourth region is extracted using the above method, but it is not limited to the above method as long as a region where the color information changes continuously can be set as the image data. For the image data in FIG. 11, the region filled with black shown in FIG. 13(a) is set as the fourth region, and the region filled with white is set as the third region.

[0069] FIG. 13(b) shows the first region used to set the color conversion method of the image data set in S203 and the second region not used to set the color conversion method of the image data set in S203. In FIG. 13(b), the first region is shown as a region filled with black, and the second region is shown as a region filled with white. As described in the first embodiment, color 603 and color 604 are included in the second region. As shown in FIGS. 13(a) and 13(b), it is desirable to set the conditions for setting the first region and the second region and the conditions for setting the third region and the fourth region so that the first region used to set the color conversion method that emphasizes color discrimination is included in the third region where the color conversion method that emphasizes color discrimination can be applied. That is, it is desirable to set the region used to set the color conversion method that emphasizes color discrimination so that it does not become a region where the color conversion method that emphasizes color discrimination is not applied.

[0070] Next, in S402, the CPU 102 creates color conversion tables for the third area and the fourth area set in S401. Since the color conversion table for the third area is the same as that in the first embodiment, the description thereof is omitted. As the color conversion table for the fourth area, a tone-emphasized color conversion table stored in the storage medium 104 in advance, which is different from the color conversion table stored in the storage medium 104 in advance used in S202, is set. Also, the tone-emphasized color conversion table is different from the color conversion table applicable to the third area.

[0071] Next, in S403, the CPU 102 performs color conversion based on the following information.

[0072] · Area information in S401 · Color conversion table for the third area set in S402 · Tone-emphasized color conversion table stored in the storage medium 104 in advance for the fourth area set in S402 For the image data acquired in S201, for the third area extracted in S401, image data after color conversion is generated by performing calculations using the color conversion table for the third area set in S402. On the other hand, for the fourth area extracted in S401, image data after color conversion is generated by performing calculations using the tone-emphasized color conversion table stored in the storage medium 104 in advance set in S402. The generated image data is stored in the RAM 103 or the storage medium 104.

[0073] According to this embodiment, by setting the first area used for setting the color conversion method of the image data and the second area not used for setting the color conversion method of the image data, an appropriate color conversion method can be set based on the information of the area necessary for color conversion. In addition, a third area to which the color conversion method is applied and a fourth area to which the color conversion method is not applied, which are different from the setting of the area for setting the color conversion method, are set. Thereby, color conversion can be performed only on the areas where the image quality does not deteriorate even when the set color conversion method is applied.

[0074] In the present embodiment, an area where image quality deteriorates when the color conversion method generated from the first area is applied to the image data is set as the fourth area, and an example is shown in which image quality deterioration is avoided by not applying the color conversion method generated from the first area to the fourth area. However, the third area and the fourth area may be separated by setting a third area where no image quality deterioration occurs even when the color conversion method generated from the first area is applied to the image data.

[0075] In the present embodiment, a tone-emphasis color conversion table stored in the storage medium 104 in advance is applied to the fourth area, but if the color conversion table stored in the storage medium 104 in advance used in S202 of the first embodiment is applicable, a configuration in which it is applied may also be used.

[0076] As described above, each embodiment has been described, but the scope is not limited to that described in the above embodiments. It is obvious to those skilled in the art that various changes or improvements can be made to the above embodiments. Forms with such changes or improvements may also be included in the technical scope of the present invention.

[0077] In each embodiment, an example of setting a color conversion table that reduces color degradation and enables the colors on the original data to be distinguishable in the output is described based on the color information in the first region. When a color conversion method that emphasizes color discrimination is set, image quality degradation may occur in the region that emphasizes gradation. Therefore, an example of extracting a region that emphasizes gradation as the fourth region is described. However, it is not limited to this. For example, when the color reproduction range of the recording device 108 is narrow and the color reproduction range of the acquired image data is wide, the continuous gradations of the high-chroma portion of the image data may be mapped to the color reproduction range boundary of the color reproduction range of the recording device 108, resulting in a decrease in gradation. Therefore, a region that emphasizes gradation may be set as the first region. And a color conversion table that emphasizes gradation may be created from the color information in the first region. When a color conversion table that emphasizes gradation is created, applying that color conversion table to the region that emphasizes color discrimination may cause image quality degradation. Therefore, a region that emphasizes color discrimination may be set as the fourth region. As a result, it is possible to set a color conversion table that emphasizes gradation generated from the gradation region, and apply that color conversion table to a region where no image quality degradation occurs even when the color conversion table that emphasizes gradation is applied. In other words, when the operation of the above embodiment is applied with the region that emphasizes gradation as the first region and the region that emphasizes color discrimination as the fourth region, it is possible to prevent the application of the color conversion table that emphasizes gradation to the region that emphasizes color discrimination. Also, instead of the above region that emphasizes color discrimination, a region that emphasizes chroma may be set, and the operation of the above embodiment may be applied. Thereby, it becomes possible to generate a color conversion table that emphasizes chroma from the region that emphasizes chroma and apply that color conversion table to a region where no image quality degradation occurs even when the color conversion table that emphasizes chroma is applied.

[0078] In each embodiment, it may be possible to input an instruction from the user as to whether or not to perform color degradation correction. In that case, a UI screen as shown in FIG. 14 may be displayed on a display unit (not shown) mounted on the image processing apparatus 101 or the recording apparatus 108 so that a user instruction can be received. In the UI screen shown in FIG. 14, it is possible to allow the user to select the type of color correction by a toggle button. Furthermore, it is possible to allow the user to select ON and OFF as to whether or not to execute "adaptive gamma mapping" indicating the processing described in each embodiment by a toggle button. With such a configuration, it is possible to switch whether or not to execute adaptive gamma mapping according to a user instruction. As a result, when the user wants to reduce the degree of color degradation, the gamma mapping described in each embodiment can be executed.

[0079] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiment to a system or apparatus via a network or a storage medium and causing one or more processors in a computer of the system or apparatus to read and execute the program. Further, it can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

[0080] The disclosure of the present embodiment includes the following image processing apparatus, method, and program. (Item 1) Region setting means for setting, on an image represented by input image data, a first region used for setting a color conversion method of the image data and a second region not used for setting the color conversion method; When, as a result of the setting by the region setting means, the first region and the second region are included in the image, Color conversion method setting means for setting the color conversion method based on the image data of the first region set by the region setting means; Generation means for determining the color conversion method set by the color conversion method setting means as a color conversion method to be applied to a region including at least a part of the first region and the second region on the image, and generating image data after color conversion using the determined color conversion method; An image processing apparatus characterized by comprising (Item 2) Second region setting means for setting, on the image, a third region to which the color conversion method set by the color conversion method setting means is applied and a fourth region to which the color conversion method is not applied, When, as a result of the setting by the second region setting means, the third region is included in the image, The generation means determines, as a color conversion method to be applied to the third region set by the second region setting means, the color conversion method set by the color conversion method setting means, and generates image data after color conversion using the determined color conversion method. The image processing apparatus according to item 1, characterized in that (Item 3) When, as a result of the setting by the second region setting means, the fourth region is included in the image, The generation means determines, as a color conversion method to be applied to the fourth region set by the second region setting means, a color conversion method different from the color conversion method set by the color conversion method setting means. The image processing apparatus according to item 2, characterized in that (Item 4) The color conversion method set by the color conversion method setting means is not determined as a color conversion method to be applied to the fourth region. The image processing apparatus according to item 3, characterized in that (Item 5) Further comprising second color conversion method setting means for setting a second color conversion method based on the image data of the fourth region, The generation means determines, as a color conversion method to be applied to the fourth region, the second color conversion method set by the second color conversion method setting means, and generates image data after color conversion using the determined second color conversion method. The image processing apparatus according to item 3, characterized in that (Item 6) The image processing apparatus according to any one of items 2 to 5, characterized in that the fourth region is a region where the gradation continuously changes. (Item 7) The image processing apparatus according to any one of items 2 to 6, wherein the first area is included in the third area. (Item 8) The image processing apparatus according to any one of items 2 to 7, wherein the first area and the fourth area are different from each other. (Item 9) The image processing apparatus according to any one of items 2 to 8, wherein the second area is an area adjacent to the first area. (Item 10) The input image data is image data that has been resolution-converted to a low resolution and then resolution-converted back to the original resolution. The image processing apparatus according to any one of items 1 to 9, wherein the second area includes an area generated by resolution-converting to the original resolution. (Item 11) The color conversion method set by the color conversion method setting means is a color conversion method in which the third color conversion method for converting the color gamut of the input image data to the color gamut of the recording device is corrected so as to widen the reduced color intervals as a result of color conversion being performed on the first area. The image processing apparatus according to any one of items 1 to 10. (Item 12) The color conversion method set by the color conversion method setting means is a color conversion method corrected so as to widen the reduced color intervals along at least one of the directions of lightness, chroma, and hue angle as a result of color conversion being performed on the first area using the third color conversion method. The image processing apparatus according to item 11. (Item 13) The recording device is a recording device that forms an image on a recording medium by an inkjet recording method. The image processing apparatus according to item 11 or 12. (Item 14) The image processing apparatus further includes a determination means for determining whether or not to set the color conversion method by the color conversion method setting means. When the color conversion method setting means sets the color conversion method, if it is determined by the determination means, based on the image data of the first area, the color conversion method is set. The image processing apparatus according to any one of Items 11 to 13. (Item 15) Based on whether the color difference has become smaller as a result of performing color conversion by applying the third color conversion method to the first area, the determination means determines whether to set the color conversion method by the color conversion method setting means. The image processing apparatus according to Item 14. (Item 16) When the color difference becomes smaller for a predetermined number of combinations among the color differences represented by the image data of the first area, the determination means determines that the color conversion method setting means sets the color conversion method. The image processing apparatus according to Item 15. (Item 17) The color conversion method is a color conversion table. The image processing apparatus according to any one of Items 1 to 16. (Item 18) Further comprising input means for inputting image data, The input image data is the image data input by the input means. The image processing apparatus according to any one of Items 1 to 17. (Item 19) Further comprising output means for outputting the image data generated by the generation means. The image processing apparatus according to any one of Items 1 to 18. (Item 20) A method executed in an image processing apparatus, An area setting step of setting, on an image represented by input image data, a first area used for setting a color conversion method of the image data and a second area not used for setting the color conversion method, As a result of the setting in the area setting step, when the first area and the second area are included in the image, A color conversion method setting step of setting the color conversion method based on the image data of the first area set in the area setting step; As a color conversion method applied to an area including at least a part of the first area and the second area on the image, the color conversion method set in the color conversion method setting step is determined, and the image data after color conversion is generated using the determined color conversion method. A generation step; A method characterized by comprising the steps of: (Item 21) A program for causing a computer to function as each means of the image processing apparatus according to any one of Items 1 to 19.

[0081] The invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, claims are attached to disclose the scope of the invention.

Explanation of Signs

[0082] 101 Image processing apparatus: 108 Recording apparatus: 102, 111 CPU: 103, 112 RAM: 104, 113 Storage medium

Claims

1. Region setting means for setting, on the image represented by the input image data, a first region used for setting a color conversion method of the image data and a second region not used for setting the color conversion method; When, as a result of the setting by the region setting means, the first region and the second region are included in the image; Color conversion method setting means for setting the color conversion method based on the image data of the first region set by the region setting means; Determining the color conversion method set by the color conversion method setting means as the color conversion method to be applied to a region including at least a part of the first region and the second region on the image, and generating image data after color conversion using the determined color conversion method; generating means; An image processing apparatus characterized by comprising:

2. Further comprising second region setting means for setting, on the image, a third region to which the color conversion method set by the color conversion method setting means is applied and a fourth region to which the color conversion method is not applied; When, as a result of the setting by the second region setting means, the third region is included in the image; The generating means determines the color conversion method set by the color conversion method setting means as the color conversion method to be applied to the third region set by the second region setting means, and generates image data after color conversion using the determined color conversion method; The image processing apparatus according to claim 1, characterized in that:

3. When, as a result of the setting by the second region setting means, the fourth region is included in the image; The image processing apparatus according to claim 2, characterized in that the generating means determines a color conversion method different from the color conversion method set by the color conversion method setting means as the color conversion method to be applied to the fourth region set by the second region setting means.

4. The image processing apparatus according to claim 3, characterized in that the color conversion method set by the color conversion method setting means is not determined as the color conversion method to be applied to the fourth region.

5. Further comprising second color conversion method setting means for setting a second color conversion method based on the image data of the fourth region; The generation means determines, as a color conversion method to be applied to the fourth region, the second color conversion method set by the second color conversion method setting means, and generates image data after color conversion using the determined second color conversion method. The image processing apparatus according to claim 3, characterized in that.

6. The image processing apparatus according to claim 2, characterized in that the fourth region is a region where the gradation continuously changes.

7. The image processing apparatus according to claim 2, characterized in that the first region is included in the third region.

8. The image processing apparatus according to claim 2, characterized in that the first region and the fourth region are different regions from each other.

9. The image processing apparatus according to claim 2, characterized in that the second region is a region adjacent to the first region.

10. The input image data is image data that has been resolution-converted to a low resolution and then resolution-converted back to the original resolution. The image processing apparatus according to claim 1, characterized in that the second region includes a region generated by resolution-converting to the original resolution.

11. The color conversion method set by the color conversion method setting means is a color conversion method in which the third color conversion method, which converts the color gamut of the input image data to the color gamut of the recording device, is applied to the first region and the color conversion is performed, and as a result, the third color conversion method is corrected so as to widen the reduced color intervals. The image processing apparatus according to claim 1, characterized in that.

12. The color conversion method set by the color conversion method setting means is a color conversion method corrected so as to widen the reduced color intervals along at least one of the directions of lightness, chroma, and hue angle as a result of applying the third color conversion method to the first region and performing color conversion. The image processing apparatus according to claim 11, characterized in that.

13. The recording device is a recording device that forms an image on a recording medium by an inkjet recording method. The image processing apparatus according to claim 11, characterized in that.

14. The apparatus further comprises a determination means for determining whether or not to set the color conversion method by the color conversion method setting means. The color conversion method setting means sets the color conversion method based on the image data of the first region when it is determined by the determination means that the color conversion method is to be set by the color conversion method setting means. The image processing apparatus according to claim 11, characterized in that.

15. The determination means determines whether to set the color conversion method by the color conversion method setting means based on whether the color difference has become smaller as a result of performing color conversion by applying the third color conversion method to the first region. The image processing apparatus according to claim 14, characterized in that.

16. The determination means determines that the color conversion method is set by the color conversion method setting means when the color difference becomes smaller for a predetermined number of combinations among the color differences represented by the image data of the first region. The image processing apparatus according to claim 15, characterized in that.

17. The color conversion method is a color conversion table. The image processing apparatus according to claim 1, characterized in that.

18. Further comprising input means for inputting image data, The input image data is the image data input by the input means. The image processing apparatus according to claim 1, characterized in that.

19. Further comprising output means for outputting the image data generated by the generation means. The image processing apparatus according to claim 1, characterized in that.

20. A method executed in an image processing apparatus, An area setting step of setting a first area used for setting a color conversion method of image data and a second area not used for setting the color conversion method on an image represented by the input image data; As a result of the setting in the area setting step, when the first area and the second area are included in the image, A color conversion method setting step of setting the color conversion method based on the image data of the first area set in the area setting step; As a color conversion method to be applied to an area including the first area and at least a part of the second area on the image, the color conversion method set in the color conversion method setting step is determined, and the determined color conversion method is used to generate color-converted image data. A generation step; A method characterized by comprising.

21. A program for causing a computer to function as each means of the image processing apparatus according to any one of claims 1 to 19.

Images