Color conversion correction data generation apparatus, image forming apparatus, color conversion correction data generation method, and program

Abstract

To provide a color conversion correction data generation device that improves the color reproduction accuracy of color conversion using a color conversion table.SOLUTION: A color conversion correction data generation device according to an aspect of the present invention generates color conversion correction data for correcting color conversion of image data to be converted using a color conversion table, and the color conversion correction data generation device comprises: a chromaticity value acquisition unit that acquires first chromaticity value obtained from the image data to be converted and a second chromaticity value of sample image data being a result of reading a sample printed material; and an output unit that outputs the color conversion correction data generated by curve-fitting chromaticity value association data in which the first chromaticity value and the second chromaticity value acquired by the chromaticity value acquisition unit are associated with each other.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a color conversion correction data generation device, an image forming apparatus, a color conversion correction data generation method, and a program.

Background Art

[0002] Conventionally, a color conversion table used for color conversion to make the color tone of a printed matter by a printing apparatus closer to the color tone of a reference printed matter is known.

[0003] An apparatus for generating a color conversion table reads a target printed matter and a printed matter output from a printing apparatus, and generates a color conversion table from the correspondence relationship between the chromaticity values of the target printed matter with the positions thereof associated respectively, and the chromaticity values of the printed matter output from the printing apparatus (see, for example, Patent Document 1).

[0004] Also, when making the color tone of a printing apparatus closer to the color tone of a reference printing apparatus, in order to improve the reproduction accuracy of a specific color, a technique is disclosed in which an output color value of a specific color is predicted from the correspondence relationship between reference data and colorimetric values, and the correspondence relationship between the reference data and the colorimetric values is corrected according to the difference from a target color value (see, for example, Patent Document 2).

Summary of the Invention

Problems to be Solved by the Invention

[0005] For color conversion by a color conversion table, it is required to be excellent in color reproduction accuracy.

[0006] An object of the present invention is to provide a color conversion correction data generation device that improves the color reproduction accuracy of color conversion using a color conversion table.

Means for Solving the Problems

[0007] A color conversion correction data generation device according to one aspect of the present invention is a color conversion correction data generation device that generates color conversion correction data for correcting the color conversion of image data to be converted using a color conversion table, comprising: a chromaticity value acquisition unit that acquires a first chromaticity value obtained from the image data to be converted and a second chromaticity value of the sample image data which is the result of reading a sample printed material; and a chromaticity value correspondence data to which the first chromaticity value and the second chromaticity value acquired by the chromaticity value acquisition unit are associated. A chromaticity value mapping unit that generates data and the chromaticity value mapping data generated by the chromaticity value mapping unit The system includes an output unit that outputs the color conversion correction data generated by curve fitting. The chromaticity value correspondence unit generates the chromaticity value correspondence data in the hue boundary region. do. [Effects of the Invention]

[0008] According to the present invention, a color conversion correction data generation device can be provided that improves the color reproduction accuracy of color conversion using a color conversion table. [Brief explanation of the drawing]

[0009] [Figure 1] This figure illustrates the overall configuration of an image forming apparatus according to an embodiment. [Figure 2] This is a block diagram of an example hardware configuration of an image forming apparatus according to an embodiment. [Figure 3] This is a block diagram of an example of the functional configuration of the arithmetic unit according to the embodiment. [Figure 4] This is a flowchart illustrating an example of processing performed by the arithmetic unit according to the embodiment. [Figure 5] This figure illustrates the tone curve and color conversion correction data according to the first embodiment. [Figure 6] This is a block diagram of an example of the functional configuration of a color conversion correction data generation device according to the second embodiment. [Figure 7] This figure illustrates an example of hue grouping according to the second embodiment. [Modes for carrying out the invention]

[0010] The embodiments for carrying out the invention will be described below with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0011] The following description will explain an image forming apparatus having a color conversion correction data creation device according to an embodiment, as an example. This image forming apparatus is a multi-function peripheral (MFP) that has the function of printing on a recording medium such as paper, and the function of reading printed materials on which images have been formed. In the terminology of this embodiment, image forming and printing are considered synonymous.

[0012] [Embodiment] <Example of the configuration of the image forming apparatus 100> Figure 1 shows an example of the overall configuration of the image forming apparatus 100. The image forming apparatus 100 includes a paper feeder 110, a printer engine 103, a scanner 104, and a post-processing device 111, etc.

[0013] The paper feeder 110 feeds the recording medium by transporting it from a paper feed cassette, which stores recording media such as paper of different sizes, to the image formation position by the printer engine 103. The printer engine 103 performs processes such as exposure, development, charging, cleaning, fixing, and transfer, and prints on the recording medium. The scanner 104 reads the image formed on the recording medium using an optical sensor or the like. The post-processing device 111 performs post-processing such as sorting and binding on the printed material whose image has been formed by the printer engine 103.

[0014] Figure 2 is a block diagram illustrating the hardware configuration of the image forming apparatus 100. The image forming apparatus 100 includes an arithmetic unit 101, a storage device 102, an input device 105, and a control device 106, etc.

[0015] The arithmetic unit 101 is, for example, an electronic circuit such as a CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit).

[0016] The memory device 102 is, for example, a memory. As the memory, RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), etc. can be used.

[0017] The input device 105 is a device that inputs data from a peripheral device, a network, or the like. The control device 106 is a device that controls the operations of each device.

[0018] Note that the image forming apparatus 100 may be a combination of a reading device such as a scanner that reads an image formed on a recording medium, an image processing apparatus having an arithmetic unit that processes image data, etc., and an image forming apparatus that performs printing on a recording medium. For example, each device included in the image forming apparatus may be different devices connected via a network or the like.

[0019] <Functional configuration example of arithmetic unit 101> FIG. 3 is a block diagram illustrating the functional configuration of the arithmetic unit 101.

[0020] As shown in FIG. 3, the arithmetic unit 101 includes a color conversion correction data generation device 200 and a color conversion unit 210.

[0021] The arithmetic unit 101 generates color conversion correction data Dt for correcting the color conversion of the original image data Im using the color conversion table 120 by the color conversion correction data generation device 200. Further, the arithmetic unit 101 performs color conversion on the original image data Im using the color conversion correction data Dt output from the color conversion correction data generation device 200 and the color conversion table 120.

[0022] The color conversion correction data generation device 200 generates color conversion correction data Dt using the sample image data Sm that is the reading result by the scanner 104 of the sample print that serves as a sample for color conversion and the original image data Im input from the input device 105.

[0023] Here, the original image data Im is the image data to be printed by the image forming apparatus 100, and is an example of image data to be converted. Image data to be converted refers to image data that is color-converted by a color conversion table when the image forming apparatus 100 outputs a printed material based on the image data, in order to bring the color of the printed material closer to the color of the sample printed material.

[0024] The image forming apparatus 100 can bring the color of the printed material closer to that of the sample print by outputting a printed material based on the image data after the image data to be converted has been color-converted by the color conversion table. The image data to be converted may be original image data Im, or scanned image data obtained by scanning an existing printed material with a scanning device such as a scanner 104.

[0025] The color conversion correction data generation device 200 includes a rasterization unit 201, a position matching unit 202, a chromaticity value acquisition unit 203, a chromaticity value matching unit 204, a correction data generation unit 205, and an output unit 206.

[0026] The rasterization unit 201 converts the original image data Im input from the input device 105 into raster image data Im1. In this embodiment, the original image data Im is represented in the CMYK color space, with cyan (C), magenta (M), yellow (Y), and black (K) as the reference colors. The rasterization unit 201 converts the original image data Im, represented in the CMYK color space, into raster image data Im1, represented in the Lab color space.

[0027] The position matching unit 202 receives raster image data Im1 from the rasterization unit 201 and sample image data Sm from the scanner 104. The position matching unit 202 also performs pixel alignment processing between the sample image data Sm and the raster image data Im1. Pattern matching, phase-limited correlation, etc., can be used for this alignment processing method. The position matching unit 202 may also perform geometric transformation processing such as affine transformation during the alignment processing.

[0028] The chromaticity value acquisition unit 203 acquires a first chromaticity value C1, which is the chromaticity value of the provisional conversion image data Im2 obtained by color conversion of the raster image data Im1 using the color conversion table 120, and a second chromaticity value C2, which is the chromaticity value of the sample image data Sm.

[0029] The color conversion table 120 is pre-stored in the storage device 102. An existing color conversion table can be used as a base for the color conversion table 120. For example, in the case of the RGB color space, which uses red (R), green (G), and blue (B) as basic colors, sRGB can be used, and in the case of the CMYK color space, JapanColor or similar can be used.

[0030] The chromaticity value acquisition unit 203 converts the sample image data Sm, which is input from the scanner 104 and expressed in the RGB color space, into an expression in the Lab color space, and then acquires the second chromaticity value C2.

[0031] The first chromaticity value C1 and the second chromaticity value C2 are chromaticity values ​​expressed in the Lab color space. Here, the RGB color space is an example of a first color space to which the sample image data Sm is expressed, and the Lab color space is an example of a second color space.

[0032] The process of converting the sample image data Sm from the RGB color space to the Lab color space may be performed by the position mapping unit 202 or the like in a step prior to the processing by the chromaticity value acquisition unit 203.

[0033] The chromaticity value acquisition unit 203 acquires a first chromaticity value C1 and a second chromaticity value C2 for every pixel constituting the raster image data Im1 and the sample image data Sm. Alternatively, the chromaticity value acquisition unit 203 may acquire the first chromaticity value C1 and the second chromaticity value C2 for each predetermined range, such as a 5x5 pixel range, by averaging the values ​​of pixels within that range.

[0034] Table 1 shows an example of the chromaticity value of the original image data Im, the second chromaticity value C2 of the sample image data Sm represented in the Lab color space, and the first chromaticity value C1 of the provisional conversion image data Im2. Each row in Table 1 corresponds to a pixel, and the number in parentheses represents the chromaticity value. Table 1 shows the chromaticity values ​​for 6 pixels. [Table 1]

[0035] The chromaticity value mapping unit 204 generates a tone curve Tc to which the first chromaticity value C1 and the second chromaticity value C2 acquired by the chromaticity value acquisition unit 203 are mapped. This tone curve Tc is an example of chromaticity value mapping data.

[0036] The chromaticity value mapping unit 204 maps a first chromaticity value C1 and a second chromaticity value C2 to every pixel constituting the raster image data Im1 and the sample image data Sm. Alternatively, the chromaticity value mapping unit 204 maps a first chromaticity value C1 and a second chromaticity value C2 to each predetermined range, such as 5x5 pixels, in both the raster image data Im1 and the sample image data Sm.

[0037] For example, the chromaticity value mapping unit 204 can generate a tone curve Tc by plotting the first chromaticity value C1 and the second chromaticity value C2 for each pixel on a graph, as will be described later with reference to Figure 5.

[0038] The correction data generation unit 205 generates color conversion correction data Dt by curve fitting the tone curve Tc generated by the chromaticity value mapping unit 204. The color conversion correction data Dt is, for example, data obtained by curve fitting the tone curve Tc. The color conversion correction data Dt may be a mathematical formula or a lookup table, etc. In the case of Lab space, the correction data generation unit 205 generates color conversion correction data Dt for L*, a*, and b*.

[0039] The output unit 206 outputs the color conversion correction data Dt generated by the correction data generation unit 205. In this embodiment, the output unit 206 outputs the color conversion correction data Dt to the color conversion unit 210. However, it is not limited to this, and the output unit 206 can also output to the storage device 102 or an external device of the image forming apparatus 100.

[0040] The color conversion unit 210 converts the original image data Im using the color conversion correction data Dt output from the color conversion correction data generation device 200 and the color conversion table 120. Specifically, when the image forming apparatus 100 prints based on the original image data Im, the color conversion unit 210 converts the original image data Im using the color conversion table 120, and then further corrects the color of the converted original image data Im using the color conversion correction data Dt.

[0041] <Example of color conversion correction data generation process by the arithmetic unit 101> Figure 4 is a flowchart showing an example of the color conversion correction data generation process by the arithmetic unit 101. The arithmetic unit 101 starts the process shown in Figure 4, for example, in response to an operation input to the image forming apparatus 100.

[0042] First, in step S41, the arithmetic unit 101 converts the original image data Im input from the input device 105 into raster image data Im1 using the rasterization unit 201.

[0043] Next, in step S42, the arithmetic unit 101 performs pixel alignment processing between the sample image data Sm and the raster image data Im1 using the position matching unit 202.

[0044] Next, in step S43, the arithmetic unit 101 uses the chromaticity value acquisition unit 203 to acquire the first chromaticity value C1, which is the chromaticity value of the provisional conversion image data Im2 obtained by color conversion of the raster image data Im1 using the color conversion table 120, and the second chromaticity value C2, which is the chromaticity value of the sample image data Sm.

[0045] Next, in step S44, the arithmetic unit 101 generates a tone curve Tc in which the first chromaticity value C1 and the second chromaticity value C2 acquired by the chromaticity value acquisition unit 203 are associated by the chromaticity value matching unit 204.

[0046] Next, in step S45, the arithmetic unit 101 generates color conversion correction data Dt by curve fitting the tone curve Tc generated by the chromaticity value correspondence unit 204 using the correction data generation unit 205.

[0047] Next, in step S46, the arithmetic unit 101 outputs the color conversion correction data Dt generated by the correction data generation unit 205 to the color conversion unit 210 via the output unit 206.

[0048] As described above, the arithmetic unit 101 can perform the color conversion correction data Dt generation process.

[0049] [First Embodiment] <Example of tone curve Tc and color conversion correction data Dt> Figure 5 illustrates the L* color conversion correction data Dt according to the first embodiment. In Figure 5, the horizontal axis represents the first chromaticity value C1, and the vertical axis represents the second chromaticity value C2. Although Figure 5 illustrates the L* color conversion correction data Dt, the arithmetic unit 101 can similarly generate the a* and b* color conversion correction data Dt.

[0050] In Figure 5, the color conversion correction data Dt, shown as a dotted line, is an approximate curve obtained by curve fitting the tone curve Tc.

[0051] <Effects of the color conversion correction data generation device 200> A known method for achieving desired color reproduction using an image forming apparatus involves printing a color conversion table creation chart composed of multiple color patches, reading the printed color conversion table creation chart, and then generating a color conversion table from the data read from the chart.

[0052] Furthermore, a color conversion table generation device is disclosed that reads the target printout and the printout output from the printing device, and creates a color conversion table from the correspondence between the chromaticity values ​​of the target printout and the chromaticity values ​​of the printout output from the printing device, with their respective positions associated.

[0053] Furthermore, in order to improve the accuracy of reproducing specific colors when bringing the color of a printing device closer to the color of a sample printing device, a technique is disclosed that predicts the output color value of a specific color based on the correspondence between sample data and colorimetric values, and corrects the correspondence between sample data and colorimetric values ​​according to the difference from the target color value.

[0054] However, with conventional technology, if the color conversion table is used on printed materials other than the one used to generate the table, sufficient color reproduction accuracy may not be obtained, such as due to tonal steps occurring. Here, tonal steps refer to the difference in gradation that occurs between consecutive colors. Tonal steps are likely to occur in the color reproduction of colors not included in the printed material, because the printed material used to generate the color conversion table cannot contain all colors.

[0055] In this embodiment, the color conversion correction data generation device 200 has a chromaticity value acquisition unit 203 that acquires a first chromaticity value C1 obtained from original image data Im (image data to be converted) and a second chromaticity value C2 of sample image data Sm, which is the result of reading a sample print. The color conversion correction data generation device 200 also has an output unit 206 that outputs color conversion correction data Dt generated by curve fitting a tone curve Tc (chromaticity value corresponding data) to which the first chromaticity value C1 and the second chromaticity value C2 acquired by the chromaticity value acquisition unit 203 are associated.

[0056] In this embodiment, color omissions in the color conversion table 120 that occur when there are colors not included in the printed material during the generation of the color conversion table 120 are interpolated by curve fitting of the tone curve Tc, thereby suppressing gradation steps. In this embodiment, a color conversion correction data generation device is provided that improves the color reproduction accuracy of color conversion using a color conversion table by suppressing gradation steps.

[0057] Furthermore, in this embodiment, the chromaticity value acquisition unit 203 acquires the second chromaticity value C2 after converting the sample image data Sm, which is represented in the RGB color space (first color space), so that it can be represented in the Lab color space (second color space). For example, in the RGB color space, color reproduction may be reduced due to variations in the characteristics of reading devices such as the scanner 104. In this embodiment, by using the second chromaticity value C2 of the sample image data Sm, which is represented in the Lab color space, the influence of variations in the characteristics of reading devices can be suppressed, and the color conversion accuracy can be improved.

[0058] In this embodiment, an example is shown using a first chromaticity value C1 and a second chromaticity value C2 expressed in the Lab color space, but the invention is not limited to this. The color conversion correction data generation device 200 can also generate color conversion correction data Dt using a first chromaticity value C1 and a second chromaticity value C2 expressed in the CMYK color space or the RGB color space.

[0059] Furthermore, in the image forming apparatus 100 according to this embodiment, an example is shown in which the color conversion unit 210 corrects the original image data Im, which has been color converted by the color conversion table 120, using color conversion correction data Dt. However, the color conversion method by the color conversion unit 210 is not limited to this. The color conversion unit 210 may update the color conversion table 120 using the color conversion correction data Dt. For example, if the color conversion table 120 has chromaticity values ​​for each grid point of a multidimensional lookup table, the color conversion unit 210 can update the color conversion table 120 by correcting the chromaticity values ​​of each grid point using the color conversion correction data Dt.

[0060] [Second Embodiment] Next, a color conversion correction data generation device 200a according to the second embodiment will be described. Note that the same reference numerals are used for components identical to those in the first embodiment, and redundant explanations are omitted as appropriate.

[0061] In this embodiment, the first chromaticity value C1 and the second chromaticity value C2 are each grouped into multiple chromaticity groups, and the output unit 206 outputs color conversion correction data Dt generated for each of the multiple chromaticity groups.

[0062] Figure 6 is a block diagram illustrating the functional configuration of the color conversion correction data generation device 200a. The color conversion correction data generation device 200a includes a chromaticity grouping unit 207.

[0063] The chromaticity grouping unit 207 groups the first chromaticity value C1 and the second chromaticity value C2 received from the chromaticity value acquisition unit 203 into multiple hue groups.

[0064] Based on the grouped first chromaticity value C1a and second chromaticity value C2a, the chromaticity value mapping unit 204 generates a tone curve Tc for each hue group, and the correction data generation unit 205 generates color conversion correction data Dt for each hue.

[0065] The chromaticity grouping unit 207 may also group colors using saturation, lightness, etc., in addition to hue, or it may group colors using multiple color characteristics such as hue and lightness.

[0066] The hue is determined using the a* and b* values ​​in the Lab value, tan -1 It can be calculated from (b* / a*). Table 2 below shows Table 1 with hue added. The h value in the rightmost column of Table 2 represents the hue. [Table 2]

[0067] Figure 7 illustrates an example of hue grouping. Figure 7 shows an example where the circle W representing the Lab color space is grouped into three groups according to hue. In the example in Figure 7, the points 71 and 72 are grouped into three sector regions: Group G1, which includes points 72 and 73; Group G2, which includes points 72 and 73; and Group G3, which includes points 73 and 71.

[0068] Tone curves Tc may be generated for each of groups G1, G2, and G3, but this may result in a loss of color continuity. In this embodiment, tone curves Tc are generated in the boundary regions of groups G1, G2, and G3, and in regions other than the boundary regions of groups G1, G2, and G3, tone curves are generated by interpolating the generated tone curves Tc. The boundary regions of groups G1 and G2 correspond to the region on the line connecting point 72 and the center 74, the boundary regions of groups G2 and G3 correspond to the region on the line connecting point 73 and the center 74, and the boundary regions of groups G3 and G1 correspond to the region on the line connecting point 71 and the center 74.

[0069] Specifically, let Tc1 be the tone curve at the boundary region between groups G1 and G2, and Tc2 be the tone curve at the boundary region between groups G2 and G3. Also, let θ1 be the angle between the line connecting point 75 and center 74 and the line connecting point 72 and center 74, and let θ2 be the angle between the line connecting point 75 and center 74 and the line connecting point 71 and center 74. The tone curve Tc at point 75 is expressed by the following equation (1).

number

[0070] The color conversion correction data generation device 200a can also perform interpolation using the tone curve Tc0 at the center 74 where the saturation is 0, and calculate the tone curve Tc at point 75.

[0071] When the tone curve Tc is unknown, applying a previously obtained color tone curve to equation (1) yields equations for multiple tone curves. The color conversion correction data generation device 200a can calculate the optimal tone curve by solving the obtained equations using the least squares method or the like. If, as a result of grouping, no colors are included in the grouped region, the color conversion correction data generation device 200a may choose not to generate a tone curve.

[0072] The color conversion correction data generation device 200a generates color conversion correction data Dt for each of several chromaticity groups, which further suppresses gradation steps and improves color conversion accuracy compared to generating color conversion correction data Dt using the entire color space.

[0073] [Other Preferred Embodiments] In the first and second embodiments described above, the second chromaticity value of the sample image data Sm was converted using the tone curve Tc, but it is also possible to generate the tone curve after converting to a different color space.

[0074] For example, one possible configuration is to correct the chromaticity value of the original image data Im without changing the color conversion table 120 in order to approximate the color of a sample print. In this case, the color conversion table 120 searches for an input chromaticity value to output the target chromaticity value, and the relationship with the chromaticity value of the original image data Im may be expressed as a tone curve.

[0075] Here, we will explain how to correct the chromaticity value of the original image data (Im). The chromaticity value obtained from the sample image data (Sm) is inversely converted using a temporary color conversion table to convert it to the same color space as the chromaticity value of the original data.

[0076] The rightmost column in Table 3 below represents the chromaticity value of the sample image data Sm after inverse conversion using the color conversion table. This chromaticity value is expressed in the CMYK color space. [Table 3] The color conversion correction data generation device 200 or 200a creates a tone curve that associates the chromaticity value of the original image data Im with the chromaticity value obtained by inverse conversion from the sample image data Sm. In this case as well, the color conversion using the color conversion table 120 can be corrected.

[0077] For example, the input to the color conversion table 120 is corrected using a tone curve, and then the color conversion is performed using the color conversion table 120 again. The conversion result can then be saved as the chromaticity value of the corresponding grid point.

[0078] Although embodiments have been described above, the present invention is not limited to the embodiments specifically disclosed above, and various modifications and changes are possible without departing from the scope of the claims.

[0079] The embodiment also includes a method for generating color conversion correction data. For example, the color conversion correction data generation method is a color conversion correction data generation method using a color conversion correction data generation device, wherein the color conversion correction data generation device acquires a first chromaticity value obtained from the image data to be converted and a second chromaticity value of the sample image data which is the result of reading the sample printed material, and outputs the color conversion correction data generated by curve fitting the chromaticity value correspondence data to which the first chromaticity value and the second chromaticity value acquired by the acquisition unit are associated, using an output unit. The same effect as the color conversion correction data generation device described above can be obtained with such a liquid discharge method. Note that such a color conversion correction data generation method may be implemented by a CPU, LSI or other circuit, IC card or standalone module, etc.

[0080] The embodiment also includes a program. For example, the program causes the color conversion correction data generation device to perform the following processing: the acquisition unit acquires a first chromaticity value obtained from the image data to be converted and a second chromaticity value of the sample image data which is the result of reading the sample printed material; and the output unit outputs the color conversion correction data generated by curve fitting the chromaticity value correspondence data to which the first and second chromaticity values ​​acquired by the acquisition unit are associated. With such a program, the same effects as the color conversion correction data generation device described above can be obtained.

[0081] Furthermore, the ordinal numbers, quantities, and other figures used above are all illustrative to specifically explain the technology of the present invention, and the present invention is not limited to these illustrative figures. Also, the connection relationships between the components are illustrative to specifically explain the technology of the present invention, and the connection relationships that realize the functions of the present invention are not limited to these.

[0082] Furthermore, each function of the embodiments described above can be realized by one or more processing circuits. Hereinafter, "processing circuit" as used herein includes processors programmed to execute each function by software, such as processors implemented by electronic circuits, as well as devices such as ASICs (Application Specific Integrated Circuits), DSPs (digital signal processors), FPGAs (field programmable gate arrays), and conventional circuit modules designed to execute each of the functions described above. [Explanation of Symbols]

[0083] 71, 72, 73, 75 points 74 center 100 Image forming apparatus 101 Arithmetic equipment 102 Storage device 103 Printer Engine 104 Scanners 105 Input device 106 Control device 110 Paper feeder 111 Post-processing device 120 Color Conversion Table 200, 200a Color Conversion Correction Data Generation Device 201 Rasterization Section 202 Positioning attachment part 203 Chromaticity Value Acquisition Unit 204 Chromaticity Value Correspondence Section 205 Correction Data Generation Unit 206 Output section 207 Chromaticity Grouping Unit 210 Color conversion unit Dt color conversion correction data Groups G1, G2, and G3 Image data of the original document (an example of image data to be converted) Im1 raster image data Im2 temporary conversion image data Sm sample image data C1, C1a First chromaticity value C2, C2a Second chromaticity value Tc, Tc1, Tc2 tone curves W yen [Prior art documents] [Patent Documents]

[0084] [Patent Document 1] Patent No. 6150779 [Patent Document 2] Japanese Patent Publication No. 2009-049839

Claims

1. A color conversion correction data generation device that generates color conversion correction data for correcting the color conversion of image data to be converted using a color conversion table, A chromaticity value acquisition unit that acquires a first chromaticity value obtained from the image data to be converted and a second chromaticity value of the sample image data which is the result of reading the sample printout, A chromaticity value mapping unit generates chromaticity value mapping data to which the first chromaticity value and the second chromaticity value acquired by the chromaticity value acquisition unit are associated, The system includes an output unit that outputs color conversion correction data generated by curve fitting the chromaticity value correspondence data generated by the chromaticity value correspondence unit, The chromaticity value correspondence unit is a color conversion correction data generation device that generates the chromaticity value correspondence data in the hue boundary region.

2. The color conversion correction data generation device according to claim 1, wherein the chromaticity value acquisition unit converts the sample image data, which is represented in a first color space, to be represented in a second color space, and then acquires the second chromaticity value.

3. The color conversion correction data generation apparatus according to claim 1, wherein the first chromaticity value and the second chromaticity value are grouped based on hue.

4. An image forming apparatus having a color conversion unit that performs color conversion using the color conversion correction data output from the color conversion correction data generation device according to any one of claims 1 to 3 and the image data to be converted using the color conversion table.

5. A method for generating color conversion correction data using a color conversion correction data generation device, wherein the color conversion correction data generation device is The chromaticity value acquisition unit acquires a first chromaticity value obtained from the image data to be converted and a second chromaticity value of the sample image data, which is the result of reading the sample print. The chromaticity value correspondence data, to which the first chromaticity value and the second chromaticity value acquired by the chromaticity value acquisition unit are associated, is generated by the chromaticity value correspondence unit. The color conversion correction data generated by curve fitting the chromaticity value correspondence data generated by the chromaticity value correspondence unit is output by the output unit. The chromaticity value correspondence unit is a color conversion correction data generation method that generates the chromaticity value correspondence data in the hue boundary region.

6. The chromaticity value acquisition unit acquires a first chromaticity value obtained from the image data to be converted and a second chromaticity value of the sample image data, which is the result of reading the sample print. The chromaticity value correspondence data, to which the first chromaticity value and the second chromaticity value acquired by the chromaticity value acquisition unit are associated, is generated by the chromaticity value correspondence unit. The color conversion correction data generated by curve fitting the chromaticity value correspondence data generated by the chromaticity value correspondence unit is output by the output unit. The chromaticity value correspondence unit generates the chromaticity value correspondence data in the hue boundary region. A program that causes a color conversion and correction data generation device to perform the processing.

Images