JP5630231B2 - Color adjustment method, color adjustment apparatus, color adjustment program, and medium storing color adjustment program - Google Patents

Description

  The present invention relates to a color adjustment method, a color adjustment apparatus, a color adjustment program, and a medium storing a color adjustment program.

  Conventionally, an output color of a color printer is adjusted to a desired color by a color management system using a device profile.

In such a color management system, a device such as an L ^* a ^* b ^* color system or an XYZ color system from RGB values / CMYK values in a device-dependent color space such as an RGB color system or a CMYK color system. Color conversion is performed using a source profile for conversion to color system values in an independent color space, and a destination profile for conversion to CMYK values for a color printer that outputs from color space data. It has been broken.

  Further, in such a color management system, based on a normal profile, a correction profile that creates a large amount of replacement of CMY values with K values while maintaining color matching is created separately, and ink used in a color printer is used. In some cases, color materials such as toner and toner are saved to reduce the running cost of the color management system (for example, Patent Document 1).

JP 2009-17089 A

  By the way, in the conventional color management system, a plurality of profiles are often prepared and operated in response to differences in output conditions such as paper type and color matching method. In the color management system, if a profile dedicated to saving is prepared according to each condition, the profile management becomes complicated, and if multiple levels of color material savings are prepared, profiles for the number of stages are prepared. Furthermore, since it is necessary, the number becomes enormous, and it becomes more difficult to manage the number and combination of profiles.

  Furthermore, when the output status changes due to the environment of the color printer to be output or changes over time, if a profile is recreated to perform calibration, a new correction profile will be created each time, and considerable computation will be performed. It takes time and processing load is heavy.

  An object of the present invention is to store a color adjustment method, a color adjustment apparatus, a color adjustment program, and a color adjustment program that can reduce processing load and save color materials even when a profile for performing color conversion is changed. Is to provide a medium.

In order to solve the above problem, the invention according to claim 1 is a color adjustment method,
Color conversion for converting input image data into output CMYK values generated based on an output device profile indicating the relationship between input CMYK values in an output device and output color values indicating coordinates in a device-independent color space A color conversion step of obtaining output CMYK values from input image data using a table;
An input value adjustment table generated based on a difference between the output color value with respect to the input CMYK value specified from the standard profile in which the relationship between the input CMYK value and the output color value is determined in advance and the output device profile. An input value adjusting step for obtaining an adjusted CMYK value corresponding to a standard state from the output CMYK value obtained in the color conversion step, and a K component value from the adjusted CMYK value obtained in the input value adjusting step. And a component value decreasing step of obtaining a saved CMYK value by decreasing the sum of the component values of the adjusted CMYK value by decreasing the CMY component values corresponding to the K component value to be increased. Using the output value adjustment table generated by inverting the input / output values of the input value adjustment table, the component value decreasing step obtained in the step A color adjustment step having an output value adjustment step of about CMYK values to obtain the final CMYK value for outputting the image to the output device,
Only including,
In the component value reduction step, using the first saving conversion table for obtaining the output color value from the adjusted CMYK value generated based on the standard profile, the output color value from the adjusted CMYK value. And obtaining an increased K component value from the minimum value of the CMY component values in the adjusted CMYK value and the K component value in the adjusted CMYK value, and based on the first saving conversion table Output obtained from the increased K component value and the adjusted CMYK value using the second saving conversion table for obtaining the saving CMYK value from the K component value and the output color value generated Obtaining the saved CMYK value from the color value .

According to a second aspect of the invention, in the color adjustment method according to claim 1,
The second saving conversion table is set such that the sum of the component values of the saving CMYK values does not exceed a predetermined upper limit value.

According to a third aspect of the present invention, in the color adjustment method according to the second aspect ,
For the sum of the CMYK component values in the input CMYK value input to the first saving conversion table exceeding the upper limit value, the sum of the CMYK component values in the input CMYK value is less than or equal to the upper limit value. A reduction rate is calculated from the sum of CMY component values in the input CMYK values and the sum of CMY component values obtained by subtracting K component values in the input CMYK values from the target values. The rate is applied to each CMY component value in the input CMYK value to convert it into a reduced input CMYK value, and the output color value and the K component value obtained based on the converted reduced input CMYK value By setting the second saving conversion table so that saving CMYK values can be obtained, the sum of the component values of the saving CMYK values does not exceed a predetermined upper limit value. Characterized in that it is urchin set.

Invention of Claim 4 is the color adjustment method as described in any one of Claims 1-3 ,
Includes savings setting process to set savings,
In the component value decreasing step, the K component value to be increased is varied according to the saving amount set in the saving amount setting step.

The invention according to claim 5 is the color adjustment method according to any one of claims 1 to 4 ,
Output selection for selecting which of the output CMYK value obtained in the color conversion step and the final CMYK value obtained in the color adjustment step is a CMYK value for causing the output device to output an image Including a process.

According to a sixth aspect of the present invention, in the color adjustment method according to the fifth aspect ,
In the output selection step, when at least one component value of CMY in the output CMYK value obtained in the color conversion step is 0, the output CMYK value obtained in the color conversion step is used as the output device. The CMYK value is used to output an image on the screen.

The invention according to claim 7 is the color adjustment method according to claim 5 or 6 ,
In the output selection step, when the K component value in the output CMYK value obtained in the color conversion step is 0 and the minimum value among the CMY component values is less than or equal to a predetermined value, the color conversion step The output CMYK value obtained in step 1 is used as a CMYK value for causing the output device to output an image.

The invention according to claim 8 is the color adjustment apparatus,
An output device profile indicating a relationship between an input CMYK value in the output device and an output color value indicating coordinates in a device-independent color space, and from input image data generated based on the output device profile to an output CMYK value A storage unit for storing a color conversion table for conversion, and a standard profile in which a relationship between an input CMYK value and the output color value is predetermined;
An output value adjustment table is generated based on a difference of the output color value with respect to an input CMYK value specified from the standard profile and the output device profile, and an output in which input / output values of the input value adjustment table are inverted A value adjustment table is generated, an output CMYK value is obtained from input image data using the color conversion table, and an adjustment CMYK value corresponding to a standard state is obtained from the output CMYK value using the input value adjustment table. The total of the component values of the adjusted CMYK value is reduced by increasing the K component value from the adjusted CMYK value and decreasing the CMY component values corresponding to the increased K component value. A value is obtained, and an image is output from the saved CMYK value to the output device using the output value adjustment table. A control unit for acquiring the final CMYK value,
Equipped with a,
The control unit obtains the output color value from the adjusted CMYK value using the first saving conversion table for obtaining the output color value from the adjusted CMYK value generated based on the standard profile. Then, an increased K component value is obtained from the minimum value of the CMY component values in the adjusted CMYK value and the K component value in the adjusted CMYK value, and generated based on the first saving conversion table The output color value obtained from the increased K component value and the adjusted CMYK value using the second saving conversion table for obtaining the saved CMYK value from the K component value and the output color value To obtain the saved CMYK value .

The invention according to claim 9 is the color adjustment apparatus according to claim 8 ,
The control unit may generate the second saving conversion table such that a total of the component values of the saving CMYK values does not exceed a predetermined upper limit value.

According to a tenth aspect of the present invention, in the color adjustment apparatus according to the ninth aspect ,
The control unit calculates the sum of the CMYK component values in the input CMYK value when the sum of the CMYK component values in the input CMYK value that is input to the first saving conversion table exceeds the upper limit value. It converts to a target value that is less than or equal to the upper limit value, and the reduction rate is calculated from the sum of CMY component values in the input CMYK values and the sum of CMY component values obtained by subtracting K component values in the input CMYK values from the target values Calculate and apply the reduction rate to each CMY component value in the input CMYK value to convert it into a reduced input CMYK value, and output color values obtained based on the converted reduced input CMYK values and K By generating the second saving conversion table so that the saving CMYK value is obtained from the component value, the sum of the component values of the saving CMYK value is a predetermined upper limit. Characterized in that it does not exceed.

The invention according to claim 11 is the color adjustment apparatus according to any one of claims 8 to 10 ,
The control unit sets a saving amount and varies the K component value to be increased according to the set saving amount.

The invention according to claim 12 is the color adjustment apparatus according to any one of claims 8 to 11 ,
The control unit may select which of the output CMYK value and the final CMYK value is a CMYK value for causing the output device to output an image.

The invention described in claim 13 is the color adjustment apparatus according to claim 12 ,
The control unit is characterized in that when at least one component value of CMY in the output CMYK value is 0, the output CMYK value is set as a CMYK value for causing the output device to output an image.

The invention described in claim 14 is the color adjustment apparatus according to claim 12 or 13 ,
The control unit causes the output device to output an image when the K component value in the output CMYK value is 0 and the minimum value among the CMY component values is equal to or less than a predetermined value. Therefore, the CMYK value is used.

The invention according to claim 15 is :
Computer
A standard profile in which a relationship between an input CMYK value and an output color value indicating coordinates in a device-independent color space is predetermined, and an output device profile that indicates a relationship between the input CMYK value in the output device and the output color value An input value adjustment table is generated based on the difference of the output color value with respect to the input CMYK value specified from the above, and an output value adjustment table in which input / output values of the input value adjustment table are inverted is generated, and the output device An output CMYK value is obtained from the input image data using a color conversion table for converting the input image data into an output CMYK value generated based on the profile, and the output CMYK value is obtained using the input value adjustment table. get the adjustment CMYK values corresponding to the standard state from the said adjustment CMYK values, increasing the K component value In addition, the CMYK component value corresponding to the K component value to be increased is decreased to obtain a saved CMYK value in which the sum of the component values of the adjusted CMYK value is decreased, and the output value adjustment table is used. A color adjustment program for functioning as control means for obtaining a final CMYK value for causing the output device to output an image from the saved CMYK value ,
The control means obtains the output color value from the adjusted CMYK value using a first saving conversion table for obtaining the output color value from the adjusted CMYK value generated based on the standard profile. Then, an increased K component value is obtained from the minimum value of the CMY component values in the adjusted CMYK value and the K component value in the adjusted CMYK value, and generated based on the first saving conversion table The output color value obtained from the increased K component value and the adjusted CMYK value using the second saving conversion table for obtaining the saved CMYK value from the K component value and the output color value To obtain the saved CMYK value .

The invention according to claim 16 is the color adjustment program according to claim 15 ,
Wherein, the sum of the component values of the savings CMYK values and wherein the benzalkonium generates said second save conversion table so as not to exceed a predetermined upper limit value.

The invention described in claim 17 is the color adjustment program according to claim 16 ,
The control means calculates the sum of the CMYK component values in the input CMYK value when the sum of the CMYK component values in the input CMYK value input to the first saving conversion table exceeds the upper limit value. It converts to a target value that is less than or equal to the upper limit value, and the reduction rate is calculated from the sum of CMY component values in the input CMYK value and the sum of CMY component values obtained by subtracting the K component value in the input CMYK value from the target value. Calculate and apply the reduction rate to each CMY component value in the input CMYK value to convert it into a reduced input CMYK value, and output color values obtained based on the converted reduced input CMYK values and K By generating the second saving conversion table so that the saving CMYK value can be obtained from the component value, the sum of the component values of the saving CMYK value is increased by a predetermined amount. And wherein the to Turkey so as not to exceed the value.

The invention according to claim 18 is the color adjustment program according to any one of claims 15 to 17 ,
Said control means sets the savings, depending on the savings that are the set, characterized by a variable to Turkey an increased to K component value.

The invention according to claim 19 is the color adjustment program according to any one of claims 15 to 18 ,
The control means and Turkey to choose a CMYK value for outputting the image either with the final CMYK value and the output CMYK values to the output device.

The invention according to claim 20 is the color adjustment program according to claim 19 ,
Wherein, when at least one of component values of CMY at the output CMYK value is 0, and wherein the CMYK values and to Turkey for outputting an image the output CMYK values to the output device To do.

The invention according to claim 21 is the color adjustment program according to claim 19 or 20 ,
The control means causes the output device to output an image of the output CMYK value when the K component value in the output CMYK value is 0 and the minimum value among the CMY component values is not more than a predetermined value. and wherein the CMYK values and to Turkey for.

A twenty-second aspect of the invention is a computer-readable medium storing the color adjustment program according to any one of the fifteenth to twenty- first aspects.

  According to the present invention, even if the profile for performing color conversion is changed, the processing load can be reduced and the color material can be saved.

1 is a system configuration diagram of a color adjustment system according to the present embodiment. It is a block diagram which shows the functional structure of client PC. It is explanatory drawing of a 1st LUT. It is a schematic diagram showing a color chart. FIG. 5 is a schematic diagram showing a state where a color patch of K: 0% is arranged in the color chart of FIG. 4. It is a figure which shows the distribution of the sample point on the locus | trajectory by the value of CMY, and the value of a color system, and the point which performs an interpolation process. It is the figure which showed the order of the interpolation process about the combination of the value of CMY. It is a figure showing the one-dimensional LUT which converts each value of CMYK. It is explanatory drawing of a 2nd LUT. It is a figure which shows target value T 'in an a ^* L ^* coordinate system. It is a figure which shows the target value T in CM coordinate system. It is the figure which expanded the area | region V0 shown in FIG. FIG. 13 is a diagram illustrating a region V0 ′ corresponding to the region V0 illustrated in FIG. 12 in the a ^* L ^* coordinate system. It is a figure explaining color gamut mapping. It is a flowchart explaining the production | generation procedure of a device link profile. It is a flowchart explaining a CMYK input value correction curve generation process. It is a flowchart explaining an input value correction curve generation process. It is a flowchart explaining a CMYK output value correction curve generation process. It is a flowchart explaining the conversion table creation process for saving mode (low). It is a flowchart explaining the conversion table creation process for saving modes (large). It is a flowchart explaining the conversion table creation process for saving modes (large). It is a flowchart explaining a total amount restriction | limiting setting process. It is a figure explaining the change of a color gamut. It is a flowchart explaining a color conversion process. It is a figure explaining a K version production | generation curve. It is a figure explaining a saving mode selection process. It is a flowchart explaining the device link profile production | generation process for saving modes.

  Hereinafter, a color adjustment system according to an embodiment of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In addition, in the following description, what has the same function and structure attaches | subjects the same code | symbol, and abbreviate | omits the description.

  Further, in the embodiment of the present invention, the entire color adjustment system is referred to as a color adjustment system as a whole, but a part or all of the devices constituting the color adjustment system can of course be referred to as a color adjustment apparatus. It is.

  FIG. 1 shows an example of the configuration of a color adjustment system 1000 according to the present invention. The color adjustment system 1000 includes, for example, a color printer 1, a controller 2, a measuring device 3, and a client PC (Personal Computer) 10. The color adjustment system 1000 adjusts the color of image data output from a device (target device) that is a target of color adjustment, and reproduces the color of the image data with the color printer 1 (destination device). In the following description, the target device is assumed to be a color monitor device that outputs RGB color image data.

  The color printer 1 outputs a CMYK color image composed of three basic colors of CMY (cyan, magenta, yellow) and K (black) having different hues. The color printer 1 is connected to the controller 2 via a communication interface.

The controller 2 is a PC or the like. The controller 2 acquires a print job from another computer connected via the network. Then, the controller 2 generates raster image data by RIP (Raster Image Processor) development processing for the acquired print job.
Further, the controller 2 stores the device link profile transmitted from the client PC 10 in a storage device such as an HDD. The controller 2 can perform color conversion processing on the generated image data using a device link profile. The controller 2 transmits the image data subjected to the color conversion process to the color printer 1 for output.
Here, the device link profile is a profile obtained by integrating the device profile of the color monitor device and the device profile of the color printer 1. Specifically, the device link profile associates the RGB values of the color monitor device with the CMYK values of the color printer 1 without using a color space that does not depend on the device. Therefore, the controller 2 can directly convert RGB image data output from the color monitor device into CMYK colors using the device link profile.
In this embodiment, in order to reduce the amount of color material (toner material) used by the color printer 1, the controller 2 sends a saving mode conversion table and an input value transmitted from the client PC 10 as will be described later. The correction curve and the output value correction curve are stored in a storage device such as an HDD. Based on these, the controller 2 can correct the CMYK image data converted by the device link profile.

The measuring device 3 measures a color chart or spot color chart output from the color printer 1. Specifically, the measuring device 3 spectroscopically measures the color of each color patch included in the color chart and the color chart of the spot color. Then, the measuring instrument 3 transmits the measured value of the measured color to the client PC 10. Here, the measurement value obtained by the measuring instrument 3 is represented by a spectral reflectance value, a value of a color system that does not depend on a device such as XYZ and L ^* a ^* b ^* determined by the International Commission on Illumination (CIE), and the like. . Here, the spot color is not a color constituted by a combination of CMYK color materials, but other colors that cannot be represented by CMYK, or offset printing that is created by mixing each color material of CMYK. It is a special color ink used and may be included in image data for offset printing. Since the color printer 1 cannot output such a spot color as it is, it is necessary to perform measurement by the measuring device 3 and convert it into CMYK values as described later.
The measuring device 3 is connected to the client PC 10 via a communication interface. In addition, when the measurement value by the measuring device 3 is expressed by the spectral reflectance value or the XYZ value, the client PC 10 converts the measurement value into an L ^* a ^* b ^* value or a CIECAM02 value. Also good.
In the present embodiment, a case where the value of L ^* a ^* b ^* is used as a measurement value by the measuring device 3 will be described.

  For example, as shown in FIG. 2, the client PC 10 includes a CPU (Central Processing Unit) 11, a RAM (Random Access Memory) 12, a ROM (Read Only Memory) 13, an operation unit 14, a display unit 15, The storage unit 16 and the communication unit 17 are included.

The CPU 11 executes various programs (program codes) stored in the ROM 13 in accordance with input signals input from each unit of the client PC 10. Furthermore, the CPU 11 outputs an output signal to each unit based on the program related to the execution, and controls the overall operation of the client PC 10.
The CPU 11 creates a device profile for the color printer 1, for example. Further, the CPU 11 creates a device link profile using the device profile of the color printer 1 and the device profile of the color monitor device. That is, the CPU 11 adjusts the color of the image data output from the color monitor device, and creates a color conversion table for reproducing the color of the image data by the color printer 1. Further, the CPU 11 creates a spot color table for reproducing the color indicated by the spot color by the color printer 1 based on the measured value of the spot color measured by the measuring device 3. Further, as will be described later, the CPU 11 creates an input value correction curve and an output value correction curve based on the color difference between the standard state of the color printer 1 and the current state. Further, as will be described later, the CPU 11 creates a saving mode conversion table used in a saving mode for reducing the amount of color material (toner material) used by the color printer 1.

  The RAM 12 forms a work area for temporarily storing various programs executed by the CPU 11 and data related to the programs.

  The ROM 13 is composed of a nonvolatile semiconductor memory or the like. The ROM 13 is a medium that stores various programs executed by the CPU 11 in the form of program codes readable by the CPU 11. The ROM 13 stores parameters, files, and the like that are necessary for the CPU 11 to execute the program.

  The operation unit 14 includes a keyboard having cursor keys, character input keys, and various function keys, and a pointing device such as a mouse. The operation part 14 will output the operation signal according to operation content to CPU11, if the operation input by a user is received.

  The display unit 15 is configured by an LCD (Liquid Crystal Display) or the like. The display unit 15 displays various operation screens and various processing results in accordance with instructions from the CPU 11.

The storage unit 16 is a storage device such as an HDD (Hard Disk Drive). The storage unit 16 stores a device profile, a device link profile, and a spot color table of the color printer 1 created by the CPU 11.
The storage unit 16 also stores a saving mode conversion table, an input value correction curve, and an output value correction curve created by the CPU 11.
In addition, the storage unit 16 stores a standard profile indicating a relationship between a CMYK value in a standard state of the color printer 1 determined in advance and a device-independent color system value. This standard profile may be created by a manufacturer in advance and recorded on a predetermined recording medium, or a user may arbitrarily create a device profile and use it as a standard profile. Also good. Further, a standard profile may be downloaded from the outside via a network and used.
The storage unit 16 stores a device profile in sRGB format in advance as a device profile of the color monitor device. The device profile in the sRGB format is a device profile that conforms to an international standard defined by the International Electrotechnical Commission (IEC).

The communication unit 17 is a communication interface that connects the client PC 10 to the controller 2 and the measuring device 3. The communication unit 17 transmits and receives data between the controller 2 and the measuring device 3.
For example, the communication unit 17 receives the measurement value of the color chart transmitted from the measuring device 3. The communication unit 17 also transmits the device profile, device link profile, saving mode conversion table, input value correction curve, output value correction curve, and the like stored in the storage unit 16 to the controller 2.

  Next, a procedure for creating a device profile of the color printer 1 by the client PC 10 will be described. Here, the device profile of the color printer 1 is composed of two color conversion tables, a first LUT (Look Up Table) 100 and a second LUT 200. The first LUT 100 is a profile used when the device profile is selected on the input side when performing color adjustment, and the second LUT 200 is used when the device profile is selected on the output side. The profile used.

The first LUT 100 is a color conversion table for converting a combination of CMYK values into L ^* a ^* b ^* values of the color system. For example, as shown in FIG. 3, the first LUT 100 corresponds to an LUT input point (lattice point) that is a combination of CMYK values of C × M × Y × K: 9 × 9 × 9 × 9 = 6561 points. The four-dimensional input / 3-dimensional output LUT in which the value of L ^* a ^* b ^* is entered. Here, the values of the nine CMY values are C, M, and Y: 0%, 10%, 20%, 30%, 40%, 55%, 70%, 85%, and 100%. The nine K values are K: 0%, 10%, 20%, 30%, 40%, 50%, 60%, 80%, and 100%.
A procedure for creating the first LUT 100 will be described below.

  First, the CPU 11 of the client PC 10 causes the color printer 1 to output the color chart 110 shown in FIG. 4 via the controller 2 without performing color adjustment. Here, the image data for outputting the color chart 110 is stored in advance in the storage unit 16 or the like. As the color chart 110, for example, a general color chart conforming to the ISO12642 standard is used. Any color chart can be used. The color chart 110 divides the maximum value 100% of each value of CMYK into a plurality of colors, and includes color patches of colors according to combinations of the divided CMYK values. Here, even when the color chart 110 is output without performing color adjustment, the calibration correction processing for correcting the output fluctuation of the color printer 1 in the color printer 1 or the like, the improvement of fixing property, or the high In order to improve the output stability of the density part, a process of limiting the total value of CMYK (maximum 400%) to, for example, maximum 300% may be performed. Further, in the processing by the controller 2 instead of inside the color printer 1, processing for limiting the total value of CMYK after color adjustment and before transferring to the color printer 1 may be performed. Such processing may be performed in normal output processing in addition to the output of the color chart 110.

Specifically, as shown in FIG. 4, the color chart 110 includes (1) K: 0%, (2) K: 20%, (3) K: 40%, (4) K: 60%, ( 5) K: 80%, (6) K: 100% are provided. In the color chart 110, for each of (1) to (6), a plurality of color patches in which CMY values are combined are arranged. For example, at K: 0% in (1), as shown in FIG. 5, C × M × Y: 6 × 6 × 6 color patches are arranged. Here, the respective values of the six CMY are C, M, and Y: 0%, 10%, 20%, 40%, 70%, and 100%. Similarly, the color chart 110 includes color patches (C, M, Y: 0%, 10%, 20%, 40) of C × M × Y: 6 × 6 × 6 on K: 20% of (2). %, 70%, 100%), K: 40% of (3), C × M × Y: 5 × 5 × 5 color patches (C, M, Y: 0%, 20%, 40%) , 70%, 100%) to K: 60% of (4), C × M × Y: 5 × 5 × 5 point color patches (C, M, Y: 0%, 20%, 40%, 70%, 100%) to K: 80% of (5), C × M × Y: 4 × 4 × 4 color patches (C, M, Y: 0%, 40%, 70%, 100) %), K: 100% of (6), and C × M × Y: 2 × 2 × 2 color patches (C, M, Y: 0%, 100%), respectively. The color chart 110 includes (7) 13 gradation steps for each CMYK single color (3%, 7%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%). 70%, 80%, 90%).
That is, the color chart 110 includes 806 color patches of C × M × Y × K: 754 points + monochromatic 52 points in total of (1) to (7).

Next, the user measures each color patch of the output color chart 110 with the measuring device 3 in order. Then, the CPU 11 uses the measuring device 3 to obtain L ^* a ^* b ^* values (measured values) corresponding to the CMYK value combinations of 754 points and the CMYK single color 52 point values, respectively. You can get it.

Next, the CPU 11 calculates the values of L ^* a ^* b ^* corresponding to the combinations of CMYK values of C × M × Y × K: 9 × 9 × 9 × 9 = 6531 points, except for the above 806 points. To do.
Specifically, the CPU 11 uses C × M × Y: 6 × 6 × 6 points in (1) as sample points, and uses each value of CMY monochromatic gradation steps in (7) to obtain C × M × Y: Interpolation processing is performed for points with no measurement value (C, M, Y: 30%, 55%, 85%) among 9 × 9 × 9 points, and L ^* a ^* b ^{* of the} point with no measurement value Is calculated. Next, the CPU 11 (C) of (2) C × M × Y: 6 × 6 × 6 points, (3) C × M × Y: 5 × 5 × 5 points, (4) C × M × Y: Similar interpolation processing is performed for each of 5 × 5 × 5 points, (5) C × M × Y: 4 × 4 × 4 points, and (6) C × M × Y: 2 × 2 × 2 points. And calculate the value of L ^* a ^* b ^{* at} the point where there is no measured value. That is, the CPU 11 can interpolate C × M × Y × K: 9 × 9 × 9 × 6 points by performing interpolation processing using C × M × Y × K: 754 points as sample points.
Further, the CPU 11 performs the following interpolation processing for three points (K: 10%, 30%, 50%) having no measurement value among the K: 9 points. That is, for K: 10% C × M × Y: 9 × 9 × 9 points, the already obtained K: 0% C × M × Y: 9 × 9 × 9 points L ^* a ^* Interpolation processing is performed using the b ^* value, K: 20% C * M * Y: 9 * 9 * 9 L ^* a ^* b ^* values, and K monochromatic gradation step values. Go to calculate the value of L ^* a ^* b ^* for each point. In addition, for K: 30% C × M × Y: 9 × 9 × 9 points, the already obtained K: 20% C × M × Y: 9 × 9 × 9 points L ^* a ^* Interpolation is performed using the b ^* value, K: 40% C × M × Y: 9 × 9 × 9 point L ^* a ^* b ^* values, and K monochromatic gradation step values. Go to calculate the value of L ^* a ^* b ^* for each point. In addition, for K: 50% C × M × Y: 9 × 9 × 9 points, the already obtained K: 40% C × M × Y: 9 × 9 × 9 points L ^* a ^* Interpolation is performed using the b ^* value, K: 60% C × M × Y: 9 × 9 × 9 point L ^* a ^* b ^* values, and K monochromatic gradation step values. Go to calculate the value of L ^* a ^* b ^* for each point.
As described above, the CPU 11 can acquire the value of L ^* a ^* b ^* for the LUT input points of C × M × Y × K: 9 × 9 × 9 × 9 = 6561 points in the first LUT 100.

Incidentally, the interpolation processing is described in detail in, for example, Japanese Patent Application Laid-Open No. 2003-78773. As an example, the interpolation processing using (4) C × M × Y: 5 × 5 × 5 points as sample points will be briefly described.
CPU11 is the ^L * ^a * ^{b *} values of points for performing an interpolation process (not a point of measurement), and the sample point ^L * ^a * ^{b *} values, and the value of gradation steps in a single color of CMY, Calculate with Here, L ^* a ^* b ^{* at the} point where interpolation processing is performed is Lm ^* am ^* bm ^* , and L ^* a ^* b ^{* at} each sample point is Li ^* ai ^* bi ^* (i = 1 to 4).
In FIG. 6, the mark ● represents a sample point, and the marks Δ and x represent points at which interpolation processing is performed. The CPU 11 uses Lm ^* am by using different interpolation formulas when there are two sample points each before and after as indicated by Δ and when there are one and three sample points before and after as indicated by ^{×. *} Calculate the value of bm ^* .
Specifically, the interpolation equation for the former (Δ mark) is obtained by the following equations (1) to (3).
Lm ^* = − (1/16) L1 ^* + (9/16) L2 ^* + (9/16) L3 ^* − (1/16) L4 ^* (1)
am ^* = − (1/16) a1 ^* + (9/16) a2 ^* + (9/16) a3 ^* − (1/16) a4 ^* (2)
bm ^* = − (1/16) b1 ^* + (9/16) b2 ^* + (9/16) b3 ^* − (1/16) b4 ^* (3)
On the other hand, the interpolation formula for the latter (x mark) is obtained by the following formulas (4) to (6).
Lm ^* = (5/16) L1 ^* + (15/16) L2 ^* − (5/16) L3 ^* + (1/16) L4 ^* (4)
am ^* = (5/16) a1 ^* + (15/16) a2 ^* -(5/16) a3 ^* + (1/16) a4 ^* (5)
bm ^* = (5/16) b1 ^* + (15/16) b2 ^* − (5/16) b3 ^* + (1/16) b4 ^* (6)
Next, the CPU 11 uses the above interpolation formula to perform interpolation processing included in C × M × Y: 9 × 9 × 9 points in the order of numbers I to III shown in FIG. Repeat the interpolation process. As a result, when the interpolation processing is completed, the CPU 11 interpolates to C × M × Y: 9 × 9 × 9 points with the sample points of C × M × Y: 5 × 5 × 5 points in (4). Can do.

As described above, the CPU 11 can create the first LUT 100. However, as described above, the CPU 11 sets the CMY values for the first LUT 100 to C, M, Y: 0%, 10%, 20%, 30%, 40%, 55%, 70%, The values of 85%, 100%, and K are set to K: 0%, 10%, 20%, 30%, 40%, 50%, 60%, 80%, and 100%. That is, each of the nine CMYK values is not a value obtained by dividing the maximum value 100% into eight equal parts.
Therefore, the CPU 11 converts each value of CMYK into a value obtained by dividing 100% into eight equal parts by using the one-dimensional LUTs 120 and 130 shown in FIG. Then, the CPU 11 performs processing for inputting the converted values of CMYK to the first LUT 100. Specifically, the CPU 11 uses the one-dimensional LUT 120, C, M, Y: 10% to 12.5%, 20% to 25%, 30% to 37.5%, 40% to 50% %, 55% to 62.5%, 70% to 75%, and 85% to 87.5%. Further, the CPU 11 uses the one-dimensional LUT 130 to change K: 10% to 12.5%, 20% to 25%, 30% to 37.5%, 40% to 50%, 50% to 62%. Convert to 5%, 60% to 75%, and 80% to 87.5%.

The second LUT 200 converts the value of L ^* a ^* b ^* into a combination of CMYK values. Second LUT200, as shown in FIG. ^{9, L * × a * ×} b *: 33 × 33 × 33 = relative LUT input point of ^L * ^a * ^{b *} values of 35937 points, CMYK values Is a 3D input / 4D output LUT. In the present embodiment, only one second LUT 200 is described. For example, it is described in PDL (Page Description Language) included in the job data of a print job transmitted from the client PC 10 or the like. A plurality of second LUTs 200 are prepared corresponding to a plurality of types of object information such as text, graphics, and images, and a plurality of types of color matching methods such as “colorimetric”, “perceptual”, and “saturation”. May be.
A procedure for creating the second LUT 200 will be described below. For simplicity, the basic color will be described as two colors C and M. Note that C, M, Y, and K all take values of 0 to 100%.

First, the CPU 11 determines the C * M * Y * K: 9 * 9 * 9 * 9 in the first LUT 100 created as described above from the four-dimensional data that are L ^* a ^* b ^* values. × M × Y: Conversion to three-dimensional data that is L ^* a ^* b ^* values for 9 × 9 × 9 is performed. For this purpose, for example, the method described in the specification of Japanese Patent No. 2898030 can be used. For example, when the K value is added to emphasize the gray component obtained from the CMY minimum value, the K value is calculated based on the CMY minimum value, and the K value is added to the CMY value. ^{* A *} b ^* Determined by determining the value.

The K value can be obtained by the following equation (7). If the minimum value of CMY is min [C, M, Y],
K = 2.0 (min [C, M, Y] -50 (%)) (7)
However, if K <0, K = 0 (%).

Further, the L ^* a ^* b ^* value when this K value is added to the value of CMY can be obtained as follows, for example. Taking the case of C = M = Y = 70% as an example, K = 2.0 × (70−50) = 40 (%), and this 40% is C × M × Y × K: 9 × 9. Since it is 40% of the fifth of 9 points (0, 10, 20, 30, 40, 50, 60, 80, 100) of × 9 × 9, L ^* a ^* b ^* value is 9 The L ^* a ^* b ^* values of C = M = Y = 70% (seventh point) and K = 40% (fifth point) among the × 9 × 9 × 9 points.
In the above, the K value is 40%, and L ^* a for one that matches one of the nine points (0, 10, 20, 30, 40, 50, 60, 80, 100) of K ^* B ^* value is explained, but when the K value does not match the above 9 points of K, the L ^* a ^* b ^* values for the upper and lower 2 points of the K value respectively. An L ^* a ^* b ^* value can be obtained by performing an interpolation by multiplying the weights and adding them together.

  The above-mentioned example is a case where C = M = Y = 70%, but by performing this for C × M × Y: 9 × 9 × 9 = 729 points, C × M × Y × K: 9 × 9 C × M × Y: 9 × 9 × 9 three-dimensional data can be created from four-dimensional data of × 9 × 9.

Next, the CPU 11 derives a combination of CMYK values for L ^* × a ^* × b ^* : 33 × 33 × 33 LUT input points.
First, in a combination of L ^* × a ^* × b ^* : 33 × 33 × 33 points, a point where a measured value of L ^* a ^* b ^* exists (that is, a point inside the color gamut of the color printer 1). A procedure for deriving a combination of CMYK values will be described. Here, the color gamut is a color range that can be expressed or reproduced by a device that performs image data output processing such as the color printer 1.
The convergence calculation process used for the derivation is described in detail in, for example, Japanese Patent Laid-Open No. 2003-78773. Here, the derivation procedure will be briefly described.

FIG. 10 shows the lightness L ^* on the vertical axis and the lightness L ^* on the horizontal axis for a combination of C × M: 9 × 9 points (Y: 0%) consisting of two-dimensional CM values among the three-dimensional CMY values. This is a coordinate system in which a ^* is plotted. In FIG. 10, H1 ′ and H2 ′ represent saturation vertices, W ′ represents a white vertex, and B ′ represents a blue vertex. In practice, the CPU 11 performs a derivation process for a three-dimensional CMY value, but for the sake of simplicity, a derivation process for a two-dimensional CM value will be described.

In FIG. 10, the target value T ′ is the value of L ^* a ^* b ^* of a target point for which a combination of CMY values is to be obtained among L ^* × a ^* × b ^* : 33 × 33 × 33 points. It is. It is assumed that the target value T ′ is present in a region V0 ′ surrounded by the lattice points a ′ to d ′ in FIG. In this case, the CPU 11 estimates that the target value T, which is a combination of CM values in the CM coordinate system, is within the region V0 surrounded by the lattice points a to d shown in FIG. In FIG. 11, H1 and H2 correspond to the saturation vertices H1 ′ and H2 ′, W corresponds to the white vertex W ′, and B corresponds to the blue vertex B ′.
Next, the CPU 11 divides the region V0 surrounded by the lattice points a to d shown in FIG. 11 into four equal regions V1 to V4 at the dividing points e to i shown in FIG. Here, the CPU 11 calculates the values of the dividing points e to i by the weighted average using the surrounding grid points that have already been obtained. Then, the CPU 11 plots the values of L ^* a ^* b ^* corresponding to the dividing points e to i in the coordinate system shown in FIG. Dividing points e ′ to i ′ shown in FIG. 13 are plot points corresponding to dividing points e to i shown in FIG.
Further, the CPU 11 determines which region of the four regions V1 ′ to V4 ′ formed by the dividing points e ′ to i ′ has the target value T ′. For example, when the target value T ′ is in the region V2 ′ as shown in FIG. 13, the CPU 11 estimates that the target value T is in the region V2 corresponding to the region V2 ′ shown in FIG.

  Next, the CPU 11 divides the estimated region V2 into regions V5 to V8, and estimates which region of the divided regions V5 to V8 has the target value T. In the same manner, the CPU 11 repeats the division / estimation of the regions, and converges the regions V0, V1 to V4, V5 to V8, V9 to V12,. Then, the CPU 11 can obtain the target value T (combination of CM values) from the average value of the four grid points or division points that form the converged area. However, the actual CPU 11 calculates the target value T (combination of CMY values) for each target point one by one for the three-dimensional CMY values. Note that the CPU 11 performs the convergence calculation process because the conversion from the coordinate system of FIG. 11 to the coordinate system of FIG. 10 is known, but the reverse conversion is very complicated and is still a good conversion formula. This is because is not known.

  In the present embodiment, the method based on the convergence calculation as described above is described. However, for example, an interpolation method described in the specification of Japanese Patent No. 2895086 may be used.

^{Then, L * × a * × b} *: Among 33 × 33 × 33 ^points, for the case where L ^* a * ^{b *} value is outside the gamut, a procedure for deriving a combination of CMYK values explain. In this case, the CPU 11 executes color gamut mapping (color gamut mapping) processing. That is, the CPU 11 maps the value of L ^* a ^* b ^{* to} a value inside the color gamut and derives a combination of CMYK values by the above-described convergence calculation process. The color gamut mapping will be described below.

FIG. 14 is a cross section obtained by cutting the L ^* a ^* b ^* color system space in a direction including the L ^* axis with a certain hue. Here, in FIG. 14, B ′ represents a black vertex (black vertex). In FIG. 14, the shaded portion having four vertices including the saturation vertex H1 ′, the white vertex W ′, the saturation vertex H2 ′, and the black vertex B ′ is the color gamut of the color printer 1.

First, the CPU 11 calculates the hue angle h and the saturation C ^* using the values of a ^* and b ^* . The hue angle h can be calculated by the following formula (13), and the saturation C ^* can be calculated by the following formula (14).
h = arctan (b ^* / a ^* ) / π × 180 (13)
C ^* = ((a ^* ^ 2) + (b ^* ^ 2)) ^ 0.5 (14)

Next, the CPU 11 obtains the lightness L ^* and saturation C ^* of the saturation vertex H1 ′, the white vertex W ′, and the black vertex B ′ for the color gamut of the color printer 1 at the hue angle h. For example, the lightness L ^* and saturation C ^* of the saturation vertex H1 ′ are calculated as follows. CPU 11 has M: 100% and C, Y: 0% point, M, Y: 100% and C: 0% point, Y: 100% and M, C: 0% point, C, A point of Y: 100% and M: 0%, a point of C: 100% and M, Y: 0%, and a point of C, M: 100% and Y: 0% are connected. And CPU11 acquires the value of L ^* a ^* b ^* corresponding to the value of CMY of each connected point. Further, the CPU 11 calculates the hue angle h and the saturation C ^* from the acquired values of L ^* a ^* b ^* at each point. Further, the lightness L ^* and the saturation C ^* of the saturation vertex H1 ′ are calculated by performing an interpolation calculation using the hue angle h and the saturation C ^* of each point calculated by the CPU 11.

Next, the CPU 11 makes the hue angle h constant and determines which of the areas P1 to P5 shown in FIG. 14 belongs to a point (input point) outside the color gamut. Then, the CPU 11 maps the input point to the color gamut based on the mapping procedure determined for each of the regions P1 to P5, and determines the target point on the color gamut corresponding to the target value T ′.
Here, in the present embodiment, the high saturation color target point r1 is determined at a position where the saturation C ^* is smaller than the saturation vertex H1 ′. That is, as shown in FIG. 14, the CPU 11 arranges the target point r1 on the saturation vertex H1 ′ side on the line segment connecting the intermediate point r2 and the saturation vertex H1 ′. Further, the CPU 11 arranges a target point r3 of a color near the white vertex W ′. The CPU 11 determines the target point r3 so as to be positioned on a line segment connecting the white vertex W ′ and the intermediate point r2. The intermediate point r2 is a point that takes an intermediate value between the lightness L ^* of the white vertex W ′ and the lightness L ^* of the black vertex B ′.

First, the CPU 11 determines the boundaries of the areas P1 to P5 shown in FIG.
Specifically, the CPU 11 determines the inclinations of the region P2 and the region P4 based on a predetermined method. Here, the area P2 is an area that is located above the color gamut and that maps to the color gamut with the inclination determined by the CPU 11. The region P4 is located below the color gamut and is a region that maps to the color gamut with an inclination determined by the CPU 11.
And CPU11 creates boundary lines q1-q4 based on the inclination of field P2 and field P4. CPU11 defines the boundary of each area | region of the area | regions P1-P5 with the created boundary lines q1-q4. The boundary line q1 is a half line extending upward from the color gamut with the inclination of the region P2 from the target point r3. The boundary line q2 is a half line extending upward from the color gamut with the inclination of the region P2 from the target point r1. The boundary line q3 is a half straight line that extends downward from the target point r1 with a slope of the region P4 toward the lower side of the color gamut. The boundary line q4 is a half line extending downward from the color gamut with the inclination of the region P4 from the black vertex B ′.
Here, in FIG. 14, the lightness L ^* of the saturation vertex H1 ′ indicates a substantially intermediate value of the maximum value 100 of the lightness L ^* . However, the lightness L ^* of the saturation vertex H1 ′ may not show the substantially intermediate value depending on the hue to be cut. For example, when cut with yellow hue, the lightness L ^* of chroma vertex H1 ', indicating high brightness L ^* than 14. Further, when cut with a blue hue, the lightness L ^* of the saturation vertex H1 ′ indicates a lightness L ^* lower than that in FIG. In such a case, it is desirable for the CPU 11 to change the slopes of the areas P2 and P4 in accordance with the slopes of the straight lines from the saturation vertex H1 ′ to the white vertex W ′ and the black vertex B ′.

Next, the CPU 11 determines the slope of the line segment connecting the input point and the target point r3, the slope of the line segment connecting the input point and the target point r1, and the line segment connecting the input point and the intermediate point r2. Is calculated. Then, CPU 11 has a respective gradients calculated, and the result of comparison between the lightness L ^* lightness L ^* and chroma vertex H1 'of the input point, based on, any region of the input point region P1~P5 Determine if it belongs to.
Next, the CPU 11 determines a target point in the color gamut for mapping the input point according to the area to which the input point belongs. For example, when the CPU 11 determines that the input point belongs to the region P1, the CPU 11 determines the target point as the target point r3. On the other hand, when the CPU 11 determines that the input point belongs to the region P3, the CPU 11 determines the target point as the target point r1. Further, when the CPU 11 determines that the input point belongs to the region P5, the CPU 11 determines the target point as the black vertex B ′. When the CPU 11 determines that the input point belongs to the region P2, the CPU 11 passes through the input point and the line segment connecting the target point r1 and the white vertex W ′ or the line segment connecting the target point r3 and the intermediate point r2 through the input point P2. The intersection point with the straight line drawn with the inclination of is determined as the target point. When the CPU 11 determines that the input point belongs to the region P4, the CPU 11 passes the line segment connecting the target point r1 and the white vertex W ′ or the line segment connecting the black vertex B ′ and the intermediate point r2 and the input point. The intersection point with the straight line extended with the inclination of P4 is determined as the target point.
As a result, the CPU 11 can map the input point whose L ^* a ^* b ^* value is outside the color gamut to the target point within the color gamut. And CPU11 acquires the combination of the value of CMYK by performing a convergence calculation process about target value T 'of the said target point.

As described above, the CPU 11 derives a combination of CMYK values for each LUT input point of L ^* a ^* b ^* : 33 × 33 × 33 = 35937 points, and generates the second LUT 200.

  Next, a procedure for creating a device link profile executed in the color adjustment system 1000 will be described with reference to FIG.

First, the color chart 110 shown in FIG. 4 is output by the color printer 1, and the color chart 110 output by the measuring device 3 is measured as described above (step S1).
Next, based on the measurement result of the color chart 110, the CPU 11 of the client PC 10 creates the first LUT 100 as described above and stores it in the storage unit 16 (step S2).
Then, the CPU 11 creates the second LUT 200 based on the created first LUT 100 as described above, and stores it in the storage unit 16 (step S3).
Then, the CPU 11 reads out the second LUT 200 created as described above and stored in the storage unit 16 and the device profile of the color monitor device stored in advance in the storage unit 16 (step S4). The device profile of the color monitor apparatus read out here is a profile for acquiring L ^* a ^* b ^* values corresponding to RGB values as inputs, and may be referred to as a source profile. Also, the second LUT 200 read out here may be referred to as a destination profile.
Then, the CPU 11 creates a device link profile by using the read second LUT 200 as the destination profile and the device profile of the color monitor device as the source profile (step S5). More specifically, first, an L ^* a ^* b ^* value corresponding to RGB values at the grid points of the source profile is used as an input value of the second LUT 200, and an output value of CMYK is obtained by interpolation calculation. Then, a device link profile is created by configuring an “RGB-CMYK LUT” having the RGB values at the grid points of the source profile as the LUT input points and the CMYK values obtained as described above as output values. This device link profile is a normal mode device link profile in which a color conversion result in a normal time is obtained, in which color materials are not reduced in a saving mode, which will be described later.
In the present embodiment, a color adjustment process for reducing the color material is performed on the CMYK values obtained as a result of color conversion using the device link profile for normal mode as follows.

  Next, processing for color adjustment performed in the color adjustment system 1000 will be described with reference to FIGS. 16 to 25.

  First, when performing color adjustment processing, an input value correction curve, an output value correction curve, and a saving mode conversion table are created. First, the CMYK input value correction curve generation process will be described with reference to FIG. The CMYK input value correction curve generation process is a process executed by the CPU 11 of the client PC 10.

  First, in order to generate an input value correction curve corresponding to the cyan (C) color, the CPU 11 sets this as a target color (step S101). Then, the CPU 11 executes an input value correction curve generation process for generating an input value correction curve for the set target color (step S102).

Here, the input value correction curve generation processing will be described in detail with reference to FIG.
First, the CPU 11 obtains respective measured values of a plurality of gradations in a single target color from the first LUT 100 (step S201). Specifically, the CPU 11 first converts an L ^* a ^* b ^* value described in a grid point indicating a single target color among the grid points of the first LUT 100 into an XYZ table according to a known conversion formula. The value is converted into a value corresponding to the complementary color of the target color among the XYZ values in the color system. In addition, each value of XYZ is represented in the range of 0-1. For example, in the case of a cyan (C) color, the color complementary to C is R in RGB. Since the value corresponding to R among the XYZ values is the X value, when the target color is cyan, the value converted from the L ^* a ^* b ^* value is the X value. In the case of a magenta (M) color, the color complementary to M is G of RGB. Of the XYZ values, the value corresponding to G is the Y value. Therefore, when the target color is magenta, the value converted from the L ^* a ^* b ^* value is the Y value. In the case of yellow (Y), the color complementary to Y is B of RGB. Of the XYZ values, the value corresponding to B is the Z value. Therefore, when the target color is yellow, the value converted from the L ^* a ^* b ^* value is the Z value. Further, among the values of XYZ, any value corresponding to the black (K) color can be adopted. However, in the present embodiment, when the target color is a black color, from the L ^* a ^* b ^* value, A value to be converted is a Y value. Next, the CPU 11 raises the value obtained by the conversion as described above to the power of 0.4 and sets it as a measured value (X value, Y value, Z value) of the gradation of the target color. In the present embodiment, the numerical value that is a power of the XYZ value obtained by conversion from the L ^* a ^* b ^* value is set to 0.4, but is not limited to this, and can be set arbitrarily.

  Then, based on the measurement value obtained in step S201, the CPU 11 generates a first conversion curve in which the measurement value is output with the gradation value (0 to 100%) of the target color as an input (step S202). ). Here, the CPU 11 calculates a measured value by interpolation calculation for the gradation for which the measured value was not obtained in step S201, and generates a first conversion curve based on the calculated value. In the present embodiment, the gradation value for calculating the measurement value is set at 5% intervals, but can be set to any gradation value such as 1% interval.

  Next, the CPU 11 reads the standard profile from the storage unit 16 and obtains respective measured values of a plurality of gradations in a single target color (step S203). Here, each value of CMYK indicated by the grid points of the standard profile is the same as that of the first LUT 100, and the CPU 11 performs the gradation measurement values (X in the target color) in the same procedure as in step S201. Value, Y value, Z value).

  Then, based on the measurement value obtained in step S203, the CPU 11 generates a second conversion curve in which a single color gradation value of the target color is output using the measurement value as an input (step S204). Here, the CPU 11 calculates a measured value by interpolation calculation for the gradation for which the measured value was not obtained in step S203, and generates a second conversion curve based on the calculated value.

  Then, the CPU 11 generates an input value correction curve for correcting the difference between the measurement values using the first conversion curve and the second conversion curve obtained as described above (step S205). The process ends. Specifically, the CPU 11 inputs the gradation value of the target color by using the first conversion curve to acquire the measurement value, and inputs the acquired measurement value by using the second conversion curve. Get the tone value. Then, the CPU 11 receives the gradation value input to the first conversion curve, and generates a correction curve that outputs the gradation value obtained by the second conversion curve.

  The CPU 11 performs the above-described processing by executing the above-described input value correction curve generation processing in Step S104, Step S106, and Step S108, respectively, while changing the target color set in Step S103, Step S105, and Step S107. , CMYK color input value correction curves are generated.

  Next, the CMYK output value correction curve generation process will be described with reference to FIG. The CMYK output value correction curve generation process is a process executed by the CPU 11 of the client PC 10.

  First, the CPU 11 generates an output value correction curve corresponding to cyan (C) color (step S301). Specifically, the output value correction curve is generated by inverting the input value and the output value of the cyan input value correction curve obtained in the CMYK input value correction curve generation process. That is, the output value correction curve is generated as a correction curve that performs a correction opposite to the input value correction curve. Hereinafter, output value correction curves respectively corresponding to magenta (M) color, yellow (Y) color, and black (K) color are similarly generated (steps S302 to S304).

Next, the saving mode (low) conversion table creation processing will be described with reference to FIG. The saving mode (small) conversion table creation process is a process executed by the CPU 11 of the client PC 10. The saving mode conversion table created by the saving mode (low) conversion table creation processing is used when a saving mode for saving 5% with a small amount of color material to be saved is implemented, as will be described later. It is a table to be. In this saving mode (small) conversion table creation process, the K value of CMYK is equally divided into eight from the standard profile stored in the storage unit 16, and each K value (0%, 12.5%) obtained by the equalization is divided. , 25%, 37.5%, 50%, 62.5%, 75%, 87.5%, and 100%), the CMY- L ^* a ^* b ^* LUT (K = n%) ”and“ L ^* a ^* b ^* −CMY LUT (K = n%) ”as a second saving conversion table Create “CMY-L ^* a ^* b ^* LUT (K = n%)” is C * M * Y: L ^* a ^* for the LUT input point that is a combination of CMY values of 9 * 9 * 9 points ^. This is a three-dimensional input / three-dimensional output LUT containing the value of b ^* . Here, the values of the 9 CMY values are C, M, Y: 0%, 12.5%, 25%, 37.5%, 50%, 62.5%, 75%, 87.5%, 100%. The value of L ^* a ^* b ^* corresponding to the CMY value that cannot be obtained directly from the standard profile can be calculated by interpolation based on the value of L ^* a ^* b ^* described at the lattice points of the standard profile. Further, ^{"L * a * b * -CMY LUT} (K = n%) " ^{is, L * × a * × b} *: the 17 × 17 × 17-dot ^L * ^a * ^{b *} of the LUT input point value On the other hand, it is a three-dimensional input / three-dimensional output LUT in which CMY values are entered, and is created based on “CMY-L ^* a ^* b ^* LUT (K = n%)”. Here, ^{"L * a * b * -CMY LUT} (K = n%) " values of ^{L *} of ^L * ^a * ^{b *} in the LUT input point has a value of 0 to 100 16 equal parts L ^* : 0, 6.25, 12.5, 18.75, 25, 31.25, 37.5, 43.75, 50, 56.25, 62.5, 68.75 75, 81.25, 87.5, 93.75, 100. Further, the values of a ^* and b ^* are values obtained by dividing the value of −128 to 128 into 16 equal parts. A ^* , b ^* : −128, −112, −96, −80, −64, − 48, −32, −16, 0, 16, 32, 48, 64, 80, 96, 112, 128.

First, the CPU 11 reads the standard profile from the storage unit 16 and, as described above, “CMY-L ^* a ^* b ^* LUT (K = 0%) corresponding to K = 0% of the K values equally divided into eight. ) "Is created (step S401). That is, the CPU 11 obtains the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points, where the K value is 0%, and converts it into an LUT.
Then, the CPU 11 uses the “CMY-L ^* a ^* b ^* LUT (K = 0%)” created as described above, and uses the “L ^* a ^* b ^* −” corresponding to K = 0%. “CMY LUT (K = 0%)” is created (step S402). The creation of “L ^* a ^* b ^* -CMY LUT (K = 0%)” is performed in the same manner as the second LUT 200 described above. When the L ^* a ^* b ^* value is outside the color gamut, the color gamut mapping process described above is applied in the creation of the second LUT 200 to derive a combination of CMY values. As described above, the CPU 11 acquires the CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 0% and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 12.5%)” corresponding to K = 12.5% (step S403). In other words, the CPU 11 obtains L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with a K value of 12.5%, and converts the L ^* a ^* b ^* values into LUTs.
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 12.5%)” created as described above, and K = 12.5% as in step S402. "L ^* a ^* b ^* -CMY LUT (K = 12.5%)" corresponding to is created (step S404). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 12.5%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 25%)” corresponding to K = 25% (step S405). That is, the CPU 11 obtains the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with a K value of 25%, and converts it into an LUT.
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 25%)” created as described above, and corresponds to K = 25% as in step S402. L ^* a ^* b ^* -CMY LUT (K = 25%) "is created (step S406). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 25%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 37.5%)” corresponding to K = 37.5% (step S407). That is, the CPU 11 acquires the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with a K value of 37.5%, and converts it into an LUT.
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 37.5%)” created as described above, and K = 37.5% in the same manner as in step S402. "L ^* a ^* b ^* -CMY LUT (K = 37.5%)" corresponding to is created (step S408). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 37.5%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 50%)” corresponding to K = 50% (step S409). That is, the CPU 11 acquires the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with a K value of 50%, and converts it into an LUT.
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 50%)” created as described above, and corresponds to K = 50% as in step S402. L ^* a ^* b ^* -CMY LUT (K = 50%) "is created (step S410). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 50%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 62.5%)” corresponding to K = 62.5% (step S411). That is, the CPU 11 obtains L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with a K value of 62.5%, and converts them into LUTs.
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 62.5%)” created as described above, and K = 62.5% in the same manner as in step S402. "L ^* a ^* b ^* -CMY LUT (K = 62.5%)" corresponding to is created (step S412). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 62.5%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 75%)” corresponding to K = 75% (step S413). That is, the CPU 11 acquires the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with the K value of 75%, and converts it into an LUT.
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 75%)” created as described above, and corresponds to K = 75% in the same manner as in step S402. L ^* a ^* b ^* -CMY LUT (K = 75%) ”is created (step S414). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 75%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 87.5%)” corresponding to K = 87.5% (step S415). That is, the CPU 11 obtains the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with the K value of 87.5%, and converts the L ^* a ^* b ^* values into LUTs.
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 87.5%)” created as described above, and K = 87.5% in the same manner as in step S402. "L ^* a ^* b ^* -CMY LUT (K = 87.5%)" corresponding to is created (step S416). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 87.5%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 100%)” corresponding to K = 100% (step S417). In other words, the CPU 11 obtains L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with a K value of 100%, and converts it into an LUT.
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 100%)” created as described above, and corresponds to K = 100% as in step S402. L ^* a ^* b ^* -CMY LUT (K = 100%) ”is created (step S418), and this process ends. That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 100%, and converts them into LUTs.

Next, the saving mode (large) conversion table creation process will be described with reference to FIGS. The saving mode (large) conversion table creation process is a process executed by the CPU 11 of the client PC 10. As will be described later, the saving mode conversion table created by the saving mode (large) conversion table creation processing is implemented with saving modes that save 10% and 20% with a large amount of color material to be saved. It is a table sometimes used. The configuration of the saving mode conversion table created by the saving mode (large) conversion table creation process is the same as the saving mode conversion table created by the saving mode (small) conversion table creation process described above. , “L ^* a ^* b ^* −CMY LUT (K = n%)” is created after reducing the color gamut of CMYK as described later, so that a conversion table in which color materials are saved can be obtained. Created.

First, the CPU 11 reads the standard profile from the storage unit 16, and performs “CMY-L ^* a ^* b ^* LUT () corresponding to K = 0% in the same manner as Step S 401 of the saving mode (low) conversion table creation process. K = 0%) "is created (step S501).
Next, the CPU 11 executes a total amount restriction setting process for reducing the CMYK color gamut (step S502).

Here, the total amount restriction setting process will be described in detail with reference to FIG.
First, the CPU 11 determines whether or not there is an LUT input point to be converted among the LUT input points in the created “CMY-L ^* a ^* b ^* LUT (K = n%)” (step S1). S601). Specifically, the CPU 11 searches for a LUT input point where the sum of the CMYK values is 220% to 400% and the CMY value has not yet been converted as a conversion target. It should be noted that the total of the CMYK values to be converted of the LUT input points can be arbitrarily set.

When the CPU 11 determines that there is an LUT input point to be converted (step S601: Y), the CPU 11 sets the K value corresponding to the “CMY-L ^* a ^* b ^* LUT (K = n%)”. At the same time, each value of CMY and the L ^* a ^* b ^* value described in the LUT input point are read from the LUT input point to be converted (step S602).

  Then, the CPU 11 performs conversion so that the total of the read CMY values and the acquired K value is 270% or less (step S603). That is, the CPU 11 converts the sum of the values of CMYK in 220% to 400% so as to be 220% to 270% using a predetermined one-dimensional LUT.

  Then, the CPU 11 subtracts the K value before conversion from the total of the CMYK values converted in step S603 to calculate the total of the converted CMY values (converted CMY total value) (step S604). ).

  Then, the CPU 11 calculates a subtraction coefficient by dividing the converted CMY total value calculated in step S604 by the total of the CMY values before conversion (pre-conversion CMY total value) (step S605).

  Then, the CPU 11 multiplies each value of CMY at the LUT input point to be read in step S602 by the subtraction coefficient calculated in step S605, and uses each value of CMY after conversion (converted CMY value). Calculate (step S606).

  The above processing will be specifically described. For example, if each value of CMYK is C = 100%, M = 100%, Y = 75%, and K = 25%, the total value of CMYK is 300%. . When the total of CMYK values after conversion using the one-dimensional LUT is 250%, the converted CMY total value is 250−25 = 225%. Since the pre-conversion CMY total value is 275%, the subtraction coefficient is 225/275 = 0.818. Then, when this subtraction coefficient is multiplied to each value of CMY before conversion, C = 81.8%, M = 81.8%, and Y = 61.4%. Note that the K value is not multiplied by a subtraction coefficient.

When each value of CMY after conversion is calculated as described above, the CPU 11 calculates “CMY-L ^* a ^* b ^* LUT (K = n%) created in the conversion table creation process for saving mode (large). ) ”Is used to obtain an L ^* a ^* b ^* value corresponding to the converted CMY value by interpolation (step S607).

Next, the CPU 11 replaces the converted CMY values and the L ^* a ^* b ^* values acquired in step S607 with the LUT input points that were read in step S602 (step S608). Transition to processing.

The CPU 11 repeatedly executes the processing of step S601 to step S608 until there is no LUT input point to be converted, so that “CMY-L ^* a ^* b ^* LUT (K = n%) ".
If the CPU 11 does not determine in step S601 that there is an LUT input point to be converted (step S601: N), the CPU 11 ends this process.

When the CPU 11 executes the total amount restriction setting process in step S502 as described above to create “CMY-L ^* a ^* b ^* LUT (K = 0%)” in which the total amount of color material is restricted. , “L ^* a ^* b ^* -CMY LUT (K = 0%)” corresponding to K = 0% is created using this “CMY-L ^* a ^* b ^* LUT (K = 0)” (Step S503). The creation of “L ^* a ^* b ^* -CMY LUT (K = 0%)” is performed in the same manner as the second LUT 200 described above. If the L ^* a ^* b ^* value is outside the color gamut, the CPU 11 derives a combination of CMY values by applying the color gamut mapping process described above in the creation of the second LUT 200. Each LUT input of “CMY-L ^* a ^* b ^* LUT (K = 0%)” that is the basis for creating “L ^* a ^* b ^* -CMY LUT (K = 0%)” created by this processing Since the sum of CMYK values at a point is limited to 270% or less, the sum of CMY values obtained by “L ^* a ^* b ^* −CMY LUT (K = 0%)” is 270%. -K value or less. That is, the sum of the CMYK values does not exceed 270%. As a result, for example, as shown in FIG. 23, the lower outer edge of the color gamut indicated by the solid line is moved up to the position indicated by the broken line, and the color gamut becomes narrower so that the low-lightness portion rises. . In the present embodiment, the total of CMYK values at each LUT input point is limited to 270% or less, but the limiting value can be arbitrarily set. In addition, “L ^* a ^* b ^* -CMY LUT (K = 0%)” created by this processing is “CMY” in which the sum of all CMYK values at each LUT input point is limited to 270% or less. -L ^* a ^* b ^* LUT (K = 0%) "is created, so the CMY values obtained by" L ^* a ^* b ^* -CMY LUT (K = 0%) "are balanced. It can be reduced while maintaining. Even when an L ^* a ^* b ^* value other than the LUT input point is input, it is obtained by interpolation from the CMY values described in the LUT input point limited to 270% or less. Regarding the colors, the sum of the CMYK values does not exceed the limit value, and the color change from the surroundings can be made continuous without being suddenly collapsed to the limit value.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 12.5%)” corresponding to K = 12.5% (step S504). In other words, the CPU 11 obtains L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with a K value of 12.5%, and converts the L ^* a ^* b ^* values into LUTs.
Then, the CPU 11 executes the above-described total amount restriction setting process to create “CMY-L ^* a ^* b ^* LUT (K = 12.5%)” in which the total amount of color material is restricted (step S505). .
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 12.5%)” in which the total amount of color materials is limited, and K = 12.5 in the same manner as in step S503. "L ^* a ^* b ^* -CMY LUT (K = 12.5%)" corresponding to% is created (step S506). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 12.5%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 25%)” corresponding to K = 25% (step S507). That is, the CPU 11 obtains the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with a K value of 25%, and converts it into an LUT.
Then, the CPU 11 executes the above-described total amount restriction setting process to create “CMY-L ^* a ^* b ^* LUT (K = 25%)” in which the total amount of color material is restricted (step S508).
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 25%)” in which the total amount of color materials is limited, and corresponds to K = 25% in the same manner as in step S503. “L ^* a ^* b ^* −CMY LUT (K = 25%)” is created (step S509). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 25%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 37.5%)” corresponding to K = 37.5% (step S510). That is, the CPU 11 acquires the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with a K value of 37.5%, and converts it into an LUT.
Then, the CPU 11 executes the above-described total amount restriction setting process to create “CMY-L ^* a ^* b ^* LUT (K = 37.5%)” in which the total amount of color material is restricted (step S511). .
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 37.5%)” in which the total amount of color materials is limited, and K = 37.5 in the same manner as in step S503. "L ^* a ^* b ^* -CMY LUT (K = 37.5%)" corresponding to% is created (step S512). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 37.5%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 50%)” corresponding to K = 50% (step S513). That is, the CPU 11 acquires the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with a K value of 50%, and converts it into an LUT.
Then, the CPU 11 executes the above-described total amount restriction setting process to create “CMY-L ^* a ^* b ^* LUT (K = 50%)” in which the total amount of color material is restricted (step S514).
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 50%)” in which the total amount of color material is limited, and handles K = 50% in the same manner as in step S503. “L ^* a ^* b ^* −CMY LUT (K = 50%)” is created (step S515). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 50%, and converts them into LUTs.

Next, as shown in FIG. 21, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 62.5%)” corresponding to K = 62.5% (step S516). That is, the CPU 11 acquires the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with the K value of 62.5%, and converts it into an LUT.
Then, the CPU 11 executes the above-described total amount restriction setting process to create “CMY-L ^* a ^* b ^* LUT (K = 62.5%)” in which the total amount of color material is restricted (step S517). .
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 62.5%)” in which the total amount of color materials is limited, and K = 62.5 in the same manner as in step S503. "L ^* a ^* b ^* -CMY LUT (K = 62.5%)" corresponding to% is created (step S518). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 62.5%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 75%)” corresponding to K = 75% (step S519). That is, the CPU 11 acquires the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with the K value of 75%, and converts it into an LUT.
Then, the CPU 11 executes the above-described total amount restriction setting process to create “CMY-L ^* a ^* b ^* LUT (K = 75%)” in which the total amount of color material is restricted (step S520).
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 75%)” in which the total amount of color materials is limited, and corresponds to K = 75% in the same manner as in step S503. “L ^* a ^* b ^* −CMY LUT (K = 75%)” is created (step S521). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 75%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 87.5%)” corresponding to K = 87.5% (step S522). That is, the CPU 11 obtains the L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with the K value of 87.5%, and converts the L ^* a ^* b ^* values into LUTs.
Then, the CPU 11 executes the above-described total amount restriction setting process to create “CMY-L ^* a ^* b ^* LUT (K = 87.5%)” in which the total amount of color material is restricted (step S523). .
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 87.5%)” in which the total amount of color materials is limited, and K = 87.5 in the same manner as in step S503. "L ^* a ^* b ^* -CMY LUT (K = 87.5%)" corresponding to% is created (step S524). That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 87.5%, and converts them into LUTs.

Next, the CPU 11 creates “CMY-L ^* a ^* b ^* LUT (K = 100%)” corresponding to K = 100% (step S525). In other words, the CPU 11 obtains L ^* a ^* b ^* values corresponding to the CMY values of the 9 × 9 × 9 points with a K value of 100%, and converts it into an LUT.
Then, the CPU 11 executes the above-described total amount restriction setting process to create “CMY-L ^* a ^* b ^* LUT (K = 100%)” in which the total amount of color material is restricted (step S526).
Then, the CPU 11 uses “CMY-L ^* a ^* b ^* LUT (K = 100%)” in which the total amount of color materials is limited, and corresponds to K = 100% in the same manner as in step S503. “L ^* a ^* b ^* −CMY LUT (K = 100%)” is created (step S527), and this process ends. That is, the CPU 11 acquires CMY values corresponding to the L ^* a ^* b ^* values of the 17 × 17 × 17 points corresponding to the K value = 100%, and converts them into LUTs.

  A color conversion process performed after the saving mode conversion table, the input value correction curve, and the output value correction curve are created as described above will be described with reference to FIG. This color conversion process is a process executed by the CPU 2 of the controller 2, for example. The color conversion processing performs color conversion for converting input image data such as CMYK and RGB into CMYK data for output by the color printer 1 and color adjustment for saving color materials. It is a process for performing. Note that various tables such as profiles used in the color conversion process are transmitted from the client PC 10 and held in the storage device of the controller 2.

First, the controller 2 determines whether the color (color data) of image data input from the client PC 10 or the like indicates a spot color (step S701). When the controller 2 determines that the input color data indicates a spot color (step S701: Y), the controller 2 uses the second LUT 200 to specify L ^* a ^* specified from the color data indicating the spot color ^. The b ^* value is converted into a CMYK value by interpolation, and this is set as C ₁ M ₁ Y ₁ K ₁ (step S702). On the other hand, when the controller 2 determines that the input color data does not indicate a spot color, that is, determines that the input color data is RGB data (step S701: N), the controller 2 uses the normal mode device link profile, The input RGB value is converted to a CMYK value by interpolation, and this is set as C ₁ M ₁ Y ₁ K ₁ (step S703).

Then, the controller 2 determines whether or not the mode is a saving mode for saving color materials (step S704). The saving mode is preset by the user, for example. When it is determined that the controller 2 is in the saving mode (step S704: Y), the controller 2 determines whether or not each value of C ₁ M ₁ Y ₁ K ₁ is 0% (step S705). When the controller 2 does not determine that each value of C ₁ M ₁ Y ₁ K ₁ is 0% (step: S705: N), the controller 2 determines whether the color is any one of CMYK. (Step S706). That is, the controller 2 determines whether or not the color is monochromatic depending on whether or not only one of the values of C ₁ M ₁ Y ₁ K _{1 is} a value other than 0%. If the controller 2 does not determine that the color is any one of CMYK (step S706: N), the controller 2 determines whether the color is an RGB secondary color (step S707). That is, the controller 2 determines whether or not the color is configured by two colors of CMY. Then, the controller 2, when not determined that the secondary color RGB (step S707: N), a value of _{K 1 0%,} the minimum value among the values of C ₁ M _{1 Y 1} Is less than or equal to a predetermined threshold (th0) (step S708). Note that the threshold value set here can be appropriately set according to the performance and state of the color printer. Then, the controller 2, a 0% value of _{K 1,} when the minimum value among the values of C ₁ M _{1 Y 1} does not equal to or less than a predetermined threshold value (step S707: N), The process of step S709 is executed. On the other hand, when the controller 2 does not determine in step S704 that the mode is the saving mode (step S704: N), in step S705, the controller 2 determines that each value of C ₁ M ₁ Y ₁ K ₁ is 0%. When (step S705: Y), when it is determined in step S706 that it is one of CMYK single colors (step S706: Y), when it is determined in step S707 that it is a secondary color of RGB (step S707: Y), and, in step S 708, a 0% value of _{K 1 is,} when the minimum value among the values of C ₁ M _{1 Y 1} is equal to or less than a predetermined threshold value (step S707: Y) The process of step S716 described later is executed.

  The color corresponding to any of the conditions in step S705 to step S708 is a color that is not subject to the process of replacing each value of CMY with the K value or the process of limiting the total value of CMYK, and is not always changed. A calculation error may occur when the above-described processing is performed on a color corresponding to such a condition in the same manner as other colors. For this reason, in the present embodiment, these conditions are determined, and for the corresponding color, in order to reduce the influence due to the calculation error, the following processing for saving the coloring material is not performed. ing.

In step S709, the controller 2 converts each value of C ₁ M ₁ Y ₁ K ₁ into each value of C _i M _i Y _i K _i using the input value correction curve (step S709). Thereby, the calibration (calibration) to the value in the standard state of each value of C ₁ M ₁ Y ₁ K ₁ is performed.

Then, the controller 2 reads the saving mode conversion table corresponding to the set saving mode (step S710). That is, if the set saving mode is a saving mode that saves 5%, the controller 2 creates “CMY-L ^* a ^* b ^* LUT ( K = n%) ”and“ L ^* a ^* b ^* -CMY LUT (K = n%) ”. If the set saving mode is a saving mode that saves 10% and 20%, the controller 2 creates “CMY-L ^* a ^* b” created by the saving mode (large) conversion table creation process. ^* LUT (K = n%) "and" L ^* a ^* b ^* -CMY LUT (K = n%) "are read.

Then, the controller 2 converts each value of C _i M _i Y _i K _i into L ^* _i a ^* _i b ^* _i using the read conversion table for saving mode (step S711). That is, the controller 2 uses corresponding respectively to the nine K values corresponding to the saving mode ^{"CMY-L * a * b *} LUT (K = n%) ", ^L _* i ^a _* i b by interpolation ^{* Get} _i . For _example, C _i M _i Y _i values _{K i} of _{the, C i = 30%, M} i = 40%, Y i = 50%, L when a ^{_{K i = 40% * i a}} * i b * _The case of acquiring _i will be described. First, an L ^* a ^* b ^* value corresponding to C _i M _i Y _i in “CMY-L ^* a ^* b ^* LUT (K = 37.5%)”, and “ L ^* a ^* b ^* values corresponding to C _i M _i Y _i in “CMY-L ^* a ^* b ^* LUT (K = 50%)” are obtained by interpolation. Then, by obtaining a weighted average of these ^L * ^a * ^{b * values,} it is possible to obtain the ^{_{L * i a * i b *}} i. The weighting amount for each L ^* a ^* b ^* value is determined according to the distance from K _i (K = 40%) of K = 37.5% and K = 50%.

  Then, the controller 2 reads the K version generation curve corresponding to the saving mode (step S712). The K version generation curve is a table stored in advance in the storage device of the controller 2 and can obtain a K value by inputting a minimum value among CMY values corresponding to gray components. As an example, FIG. 25 shows four K version generation curves of K curve 0 to K curve 3 according to the saving mode. K curve 1 to K curve 3 are used when the saving mode is 5%, 10%, and 20%, respectively, and the start point and the slope are different from each other. Further, the K curve 0 is to be applied when the saving mode is not performed.

  K curve 0 is a straight line with a start point of 50% and a slope of 2. K curve 1 is a straight line with a start point of 37.5% and a slope of 1.6. K curve 2 is a straight line with a start point of 25% and an inclination of 1.3333. K curve 3 is a straight line with a start point of 12.5% and a slope of 1.1429. The K curve 0 to the K curve 3 are all illustrated as straight lines in FIG. 25, but may be a curve in the vicinity of the start point or a curve in its entirety.

Next, the controller 2 uses the read K plane generating _curve, identifying a _{C i M i Y i K i} K o from each value of (step S713). Specifically, the controller ₂ uses as the minimum value _{(MIN [C i M i Y} i]) input value out of the values of C _i M _{i Y i,} K-plate generation curve read Get the K value. Then, the acquired K value is compared with K _i , and when the acquired K value is equal to or greater than K _i , the acquired K value is set to _Ko, and when the acquired K value is smaller than K _i , K _{Let i} be _Ko .

Next, the controller 2 uses the saving mode conversion table read, _{C o M} o _Y o to get from the _{K o} and ^{_{L * i a * i b *}} i ( step S714). That is, the controller 2 uses “L ^* a ^* b ^* -CMY LUT (K = n%)” corresponding to each of the nine K values corresponding to the saving mode, and calculates C _o M _o Y _o by interpolation calculation. get. In step S713, when the K value increases and reaches K _o , C _o M _o Y _o in which each value of CMY is decreased is acquired. That is, each value of CMY reduced by an amount corresponding to the increase amount of the K value is obtained. When K _o is between nine K values, C _o M _o Y _o can be acquired by performing the interpolation calculation in the manner described in step S711. For _example, in K o = ^42%, the values of ^{_{L * i a * i b *}} i ^{_{is, L * i = 46.8, a}} * i = -5.9, is _b * i = -3.9 _C will be described. If the o _M o to obtain a _{Y o,} first, corresponding to the ^{_{L * i a * i b *}} i in the ^{"L * a * b * -CMY LUT} (K = 37.5%) " when and the values of CMY, ^{"L * a * b * -CMY LUT} (K = 50%) " in the ^{_{L * i a * i b *}} i corresponding to the values of CMY to be acquired by each interpolation operation. Then, C _o M _o Y _o can be obtained by calculating a weighted average of these CMY values. About the weighting amount with respect to each CMY value, it calculates | requires according to each distance from _Ko (K = 42%) of K = 37.5% and K = 50%. For example, ^{"L * a * b * -CMY LUT} (K = 37.5%) " values of CMY corresponding to ^{_{L * i a * i b *}} i in is, C = 41%, M = 18%, in Y = 21%, the value of CMY corresponding to ^{_{L * i a * i b *}} i in the ^{"L * a * b * -CMY LUT} (K = 50%) " is, C = 39%, M = 11 %, Y = 12%, the weighting amount for the former is (50-42) /12.5=0.64, and the weighting amount for the latter is (42-37.5) /12.5=0. .36. As a result of calculating the weighted average of each CMY value, C _o M _o Y _o is C _o = 40%, M _o = 15%, and Y _o = 18%.

Next, the controller 2 uses the output value correction curve to convert each value of C _o M _o Y _o K _o into each value of C ₂ M ₂ Y ₂ K ₂ (step S715), and then step S717. Execute the process. That is, the controller 2 uses the output value correction curve to correct each value of CMYK calibrated to the value in the standard state so that it returns to the value corresponding to the current state of the color printer.

On the other hand, in step S716, the controller 2 directly sets each value of C ₁ M ₁ Y ₁ K ₁ as C ₂ M ₂ Y ₂ K ₂ (step S716), and executes the process of step S717. That is, the controller 2 sets the values obtained in step S702 and step S703 as values for output by the color printer 1 as they are.

Then, the controller 2 outputs the _C 2 _M 2 _Y 2 _{K 2} obtained in step S715 and step S716 (step S717), the processing ends. The color printer 1 outputs a color image based on each value of the output C ₂ M ₂ Y ₂ K ₂₋ .

  Next, the saving mode selection process will be described with reference to FIG. This saving mode selection process is a process executed by the controller 2. This saving mode selection process is executed when there is a saving mode selection instruction from the client PC 10.

  First, when there is an instruction to select a saving mode from the client PC 10, the controller 2 sets the saving mode so that the saving mode according to the content of the instruction is executed (step S801). That is, the controller 2 sets either the normal mode, the 5% saving mode for saving 5%, the 10% saving mode for saving 10%, or the 20% saving mode for saving 20%.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
[Example 1]
According to the following method, the test images of Example 1 and Comparative Example 1 were output, and the color material saving amount was evaluated. In the following examples, an N3A (fruit basket) image was used as a test image from “JIS X 9201: 2001 (ISO 12640-1: 1997) high-definition color digital standard image (CMYK / SCID)”. Further, based on the profile corresponding to the test image and the device profile in the sRGB format, the CMYK image data in the test image is converted into RGB image data, and the converted RGB value is input to output the test image. Here, as Example 1, a test image composed of CMYK color images in the 20% saving mode is output by the color printer 1 of the color adjustment system 1000 applied to the present embodiment, and a test image composed only of the C component, A test image composed of only the M component, a test image composed of only the Y component, and a test image composed of only the K component were each output using K color toner. Further, as Comparative Example 1, a test image based on a CMYK color image in a normal mode that does not save color materials is output, a test image composed only of the C component, a test image composed only of the M component, and a Y component A test image composed of only K and a test image composed only of the K component were each output using K color toner.

[result]
According to visual observation of the obtained CMYK color test image of Example 1 and the CMYK color test image of Comparative Example 1, it was found that reproducibility almost unchanged was obtained.

Then, a test image composed of only the C component of the first embodiment, a test image composed of only the M component, a test image composed of only the Y component, and a test image composed of only the C component of Comparative Example 1. According to the visual observation of the test image composed only of the M component and the test image composed only of the Y component, the CMY components of the first embodiment are each a coloring material than the CMY components of the first comparative example. It was found that each test image of Example 1 appeared lighter, and in particular, the concentration of each CMY component in the shadow portion was reduced.
On the other hand, according to visual observation of the test image composed only of the K component of Example 1 and the test image composed of only the K component of Comparative Example 1, the K component of Example 1 is It was found that the amount of the color material was larger than that of the K component of 1, and the image appeared dark overall.

  Further, when the quantity of each CMYK toner material used in the output of the test image is evaluated, the usage amount of the toner material in Example 1 is 77 when the usage amount of the toner material in Comparative Example 1 is 100%. It turned out to be 23%, and it was found that 23% was saved.

[Example 2]
Further, the test images of Example 2 and Comparative Example 2 were output according to the following method, and the color change was evaluated. In the following examples, a color chart image of “ISO 12642” was used as a test image. As Example 2, a color chart image in CMYK color in the 20% saving mode is output by the color printer 1 of the color adjustment system 1000 applied to the present embodiment, and L ^* a ^* for a predetermined 809 color patches ^. Measurement was carried out using b ^* values. Further, as Comparative Example 2, a color chart image in CMYK color in the normal mode was output, and measurement was performed with L ^* a ^* b ^* values for predetermined 809 color patches. And the color difference in Example 2 and the comparative example 2 was calculated | required for every color patch, and the average color difference and the maximum color difference were calculated | required.

[result]
As a result, the average color difference between Example 2 and Comparative Example 2 was 1.7, and the maximum color difference was 17.3. From this result, it was found that since the total amount of each component of CMYK was restricted, the maximum color difference was large, but the average color difference was small, so that high color reproduction accuracy was obtained.

As described above, according to the embodiment of the present invention, the storage unit 16 stores the input CMYK value in the color printer 1 and the output L ^* a ^* b ^* value indicating the coordinates on the device-independent color space. A first LUT 100 indicating the relationship, and a color conversion table (normal mode) for converting input image data (RGB values, L ^* a ^* b ^* values) into output CMYK values generated based on the first LUT 100 Device link profile, second LUT 200), and a standard profile in which the relationship between the input CMYK value and the output L ^* a ^* b ^* value is predetermined. The CPU 11 generates an input value adjustment table based on the difference between the output L ^* a ^* b ^* values with respect to the input CMYK values specified from the standard profile and the first LUT 100, and the input / output values of the input value adjustment table. An output value adjustment table in which is inverted is generated. Then, the controller 2 acquires the C ₁ M ₁ Y ₁ K ₁ value from the input image data using the color conversion table. Then, the controller 2 acquires the C _i M _i Y _i K _i value from the C ₁ M ₁ Y ₁ K ₁ value using the input value adjustment table. Then, the controller 2 increases the K component value from the C _i M _i Y _i K _i value and decreases the CMY component values corresponding to the increased K component value to thereby increase the C _i M _i Y _i K. _The C _o M _o Y _o K _o value obtained by reducing the sum of the component values of the _i value is acquired. Then, the controller 2 uses the output value adjustment table to obtain a C ₂ M ₂ Y ₂ K ₂ value for causing the color printer 1 to output an image from the C _o M _o Y _o K _o value. As a result, the CMYK values obtained by the color conversion table are corrected to the standard state by the input value adjustment table, and then the K value is increased to decrease each component value of the CMY value, and the output value adjustment table Therefore, even if the color conversion table is changed by changing the output condition of the color printer or re-creating the profile, it is obtained from the device that outputs the standard profile. Create an input value adjustment table and an output value adjustment table to correct the color difference from the device profile, and apply them to handle the processing to save color materials and the data table regardless of changes to the color conversion table. Can be used in common. Therefore, the processing load and processing time for changing the data table and the processing for saving the color material accompanying the change of the color conversion table are reduced. In addition, since processing for saving color materials is performed based on the CMYK values obtained from the color conversion table, CMYK for output by a color printer, with or without color material saving. The value can be easily switched.

Further, according to the embodiment of the present invention, the CPU 11 uses the first saving conversion table for obtaining the output L ^* a ^* b ^* value from the C _i M _i Y _i K _i value based on the standard profile. Is generated. Then, based on the first saving conversion table, the CPU 11 obtains a C _o M _o Y _o K _o value from the K component value and the output L ^* a ^* b ^* value. Generate a table. Then, the controller 2 acquires the output L ^* a ^* b ^* value from the C _i M _i Y _i K _i value based on the first saving conversion table. _Then, the controller 2 obtains a minimum value of the CMY component values in C _i M _i Y _{i K i value,} the K component value of the increased and a K component value of C _i M _i Y _{i K i} value To do. Then, the controller 2 uses the second saving conversion table to calculate C _o M _o from the increased K component value and the output L ^* a ^* b ^* value acquired from the C _i M _i Y _i K _i value. Get Y _o K _o value. As a result, the relationship between the K component value to be increased and decreased and the CMY component values to be decreased can be made constant regardless of the change of the color conversion table, so that less data is used to save the color material. Data management becomes easy and the memory capacity can be reduced.

Further, according to the embodiment of the present invention, the CPU 11 generates the second saving conversion table so that the total of the component values of the C _o M _o Y _o K _o values does not exceed 270%. As a result, each component value of CMYK can be defined and an image can be output, so that the management of the color material saving amount is facilitated.

Further, according to the embodiment of the present invention, the CPU 11 determines each CMYK value in the input CMYK value when the sum of the CMYK component values in the input CMYK value input to the first saving conversion table exceeds 270%. Converts the sum of component values into a target value that is 270% or less, and decreases from the sum of CMY component values in the input CMYK values and the sum of CMY component values obtained by subtracting the K component values in the input CMYK values from the target values. The rate is calculated, and the reduction rate is applied to each CMY component value in the input CMYK value to convert it into a reduced input CMYK value. The output L ^* a ^* b obtained based on the converted reduced input CMYK value ^* from the value and the K component value by generating a second save conversion table as _{C o M} o _Y o _K o value is _{obtained, C o M o Y o K} o value of component values The total should not exceed 270%. As a result, it is possible to output an image with high color reproduction accuracy while limiting the component values of CMYK.

  Further, according to the embodiment of the present invention, the controller 2 sets the saving amount. Then, the controller 2 varies the K component value to be increased according to the set saving amount. As a result, it is possible to set a saving amount in consideration of color reproduction accuracy, so that convenience can be improved.

Further, according to the embodiment of the present invention, the controller 2 uses the C ₁ M ₁ Y ₁ K ₁ value and the output value adjustment table to convert the C ₂ M converted from the C _o M _o Y _o K _o value. _{The 2} Y ₂ K _binary value is selected as the CMYK value for causing the color printer 1 to output an image. As a result, when the color material is not saved, the processing for saving the color material can be omitted by using the CMYK values obtained from the color conversion table as they are, and the processing efficiency is improved.

Further, according to the embodiment of the present invention, the controller 2 determines that the C ₁ M ₁ Y ₁ K ₁ value is at least one of the component values of CMY in the C ₁ M ₁ Y ₁ K ₁ value. Are CMYK values for causing the color printer 1 to output an image. As a result, for colors that are not subject to processing to save color materials, the CMYK values obtained from the color conversion table can be used as they are, and processing can be omitted and color materials can be saved. Therefore, it is possible to suppress a decrease in color reproduction accuracy because there is no possibility of occurrence of calculation error when performing the processing for this.

Further, according to the embodiment of the present invention, the controller 2 is configured such that when the K component in the C ₁ M ₁ Y ₁ K ₁ value is 0 and the minimum value among the CMY component values is equal to or less than a predetermined value. In addition, the C ₁ M ₁ Y ₁ K ₁ value is set as a CMYK value for causing the color printer 1 to output an image. As a result, for colors that are not subject to processing to save color materials, the CMYK values obtained from the color conversion table can be used as they are, and processing can be omitted and color materials can be saved. Therefore, it is possible to suppress a decrease in color reproduction accuracy because there is no possibility of occurrence of calculation error when performing the processing for this.

  The description in the embodiment of the present invention is an example of the color adjustment system according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of each functional unit constituting the color adjustment system can be appropriately changed.

  In the present embodiment, after color conversion is performed based on the source profile and the destination profile, the color for saving the color material by the input value correction curve, the saving mode conversion table, and the output value correction curve is used. The adjustment process is performed. For example, the device link profile for saving mode in which the RGB / CMYK values at the LUT input point of the source profile are associated with the adjusted CMYK values obtained by the color adjustment process. And color conversion processing may be performed based on this. Here, a saving mode device link profile generation process, which is an example of a process for creating a saving mode device link profile, will be described with reference to FIG. This saving mode device link profile generation processing is, for example, processing executed by the CPU 11 of the client PC 10. Note that, in the description of the saving mode device link profile generation process, only the outline of the process is described and the detailed description is omitted with respect to the contents of the process overlapping the color conversion process shown in FIG.

  First, the CPU 11 selects a saving mode (step S901). Specifically, for the selection of the saving mode, the saving mode set in the saving mode selection process shown in FIG. 26 is selected.

Next, the CPU 11 reads the normal device link profile stored in the storage unit 16, reads the output CMYK value corresponding to the input RGB value at one LUT input point from the normal device link profile, and reads this value as C ₃ and M ₃ Y ₃ K ₃ (step S902).

Then, the CPU 11 determines whether or not each value of C ₃ M ₃ Y ₃ K ₃ is 0% (step: S903). Then, when the CPU 11 does not determine that each value of C ₃ M ₃ Y ₃ K ₃ is 0% (step: S903: N), the CPU 11 determines whether the color is any one of CMYK. (Step S904). If the CPU 11 does not determine that the color is any one of CMYK (step S904: N), the CPU 11 determines whether it is an RGB secondary color (step S905). Then, CPU 11, when not determined that the secondary color RGB (step S905: N), a value of 0% of _{K 3,} the minimum value among the respective values of C ₃ M _{3 Y 3} is It is determined whether it is below a predetermined threshold value (step S906). On the other hand, when the CPU 11 determines that each value of C ₃ M ₃ Y ₃ K ₃ is 0% in step S903 (step S903: Y), it is any one of CMYK in step S904. in: (Y step S904), step S905, when it is determined that the secondary color RGB when it is judged (step S905: Y), and, in step S906, the value of _{K 3} is 0% When it is determined that the minimum value among the values of C ₃ M ₃ Y ₃ is equal to or smaller than the predetermined threshold (step S906: Y), the process of step S914 described later is executed.

In step S907, the CPU 11 converts each value of C ₃ M ₃ Y ₃ K ₃ into each value of C _i M _i Y _i K _i using the input value correction curve (step S907).
Then, the CPU 11 reads a saving mode conversion table corresponding to the set saving mode (step S908).
Then, the CPU 11 converts each value of C _i M _i Y _i K _i into L ^* _i a ^* _i b ^* _i using the read saving mode conversion table (step S909).
Then, the CPU 11 reads the K version generation curve corresponding to the saving mode (step S910).
Next, the CPU 11 specifies K _o from each value of C _i M _i Y _i K _i using the read K version generation curve (step S911).
Then, CPU 11 uses the saving mode conversion table read, _{C o M} o _Y o to get from the _{K o} and ^{_{L * i a * i b *}} i ( step S912).
Next, the CPU 11 converts each value of C _o M _o Y _o K _o into each value of C ₄ M ₄ Y ₄ K ₄ using the output value correction curve (step S913), and then in step S915. Execute the process.
On the other hand, in step S914, the CPU 11 sets each value of C ₃ M ₃ Y ₃ K ₃ as it is to C ₄ M ₄ Y ₄ K ₄ (step S914), and executes the process of step S915.

  Then, the CPU 11 determines whether conversion data creation has been completed for all the LUT input points of the normal device link profile (step S915). That is, the CPU 11 determines whether or not conversion data for each CMYK value after color adjustment has been created for all LUT input points of the normal device link profile.

When the CPU 11 does not determine that the creation of conversion data has been completed for all LUT input points (step S915: N), the CPU 11 proceeds to step S902, and conversion data to CMYK values after adjustment has not been created. The above-described processing is performed for other output CMYK values. On the other hand, when the CPU 11 determines that the creation of conversion data has been completed for all LUT input points (step S915: Y), each input RGB value and C ₄ M ₄ Y ₄ K _{4 of the} normal device link profile. Are created, a device link profile for saving mode is created with the RGB values at the lattice points of the source profile as LUT input points and the corresponding C ₄ M ₄ Y ₄ K ₄ as output values, 16 (step S916), the process is terminated.

Further, in the present embodiment, a table such as various profiles is created in the client PC 10 and processing for saving color material is executed in the controller 2. You may comprise so that it may be performed by either one of PC and a controller.
Further, each function of the client PC and the controller may be realized by a single device.
Further, the color printer may be configured to have the functions of the client PC and the controller.

  In the embodiment of the present invention, the input value and the output value are represented by a maximum value of 100% and a value of 0 to 100%. However, the maximum value is set to 255, which is a maximum value of 1 byte, and 0 to 100%. It may be expressed by a value of 255.

Further, the embodiment of the present invention can be applied to various color printers such as an electrophotographic system and an inkjet system.
In the embodiment of the present invention, the CMYK four-color printer is used. However, the present invention may be applied to a color printer including other colors such as light cyan and light magenta.

  Further, in the embodiment of the present invention, various tables such as profiles created in the client PC 10 are stored in the storage unit 16 of the client PC 10 and the table necessary for color conversion is held in the controller 2. However, a part or all of the created various tables may be stored in the controller 2.

  Further, in the embodiment of the present invention, the CMYK color data that does not save the color material is not subjected to the process for saving the color material, and is based on the CMYK value obtained by the normal color conversion process. Although output by the color printer 1 is performed, processing for saving the color material may be performed on CMYK color data that does not save the color material. For example, for a CMYK value that does not save color materials, a saving mode conversion table may be configured so that the output CMYK value does not change.

  In the embodiment of the present invention, the color adjustment system 1000 that inputs RGB color image data and obtains CMYK values is adopted. However, the color adjustment system that inputs CMYK color image data and obtains CMYK values can also be used. Good. Alternatively, both RGB image data and CMYK color image data may be input.

In the embodiment of the present invention, the color material savings that can be set are 5%, 10%, and 20%, but the savings can be arbitrarily set.
Further, although a plurality of types of color material savings that can be set are provided, one type may be used.

Further, in the embodiment of the present invention, the CMY component is decreased and the K component is increased by the saving mode conversion table in which the total amount of each component of the K plate generation curve and CMYK is limited. Although the saving is performed, the color material may be saved by only one of the K-mode generation curve and the saving mode conversion table in which the total amount of each component of CMYK is limited.
Further, the processing for saving the color material will be described in the present embodiment as long as the configuration is implemented after correcting the CMYK values obtained by the normal color conversion processing to a predetermined standard state. Not only what was done, but any aspect may be sufficient. That is, the process for saving the color material may be any process that can be used in common even if the device profile or source profile of the color printer is changed.

  In the embodiment of the present invention, the CMYK value obtained by the normal color conversion process and the CMYK value subjected to the process for saving the color material can be selectively output. However, only CMYK values for which processing for saving color materials has been performed may be output.

  In the embodiment of the present invention, a device link profile is created in normal color conversion processing, and color conversion is performed using the device link profile. However, the device link profile is not created, and the source profile and the destination profile are It may be used to perform color conversion.

  In the present embodiment, an example in which a hard disk, a semiconductor nonvolatile memory, or the like is used as a computer-readable medium for the program according to the present invention is disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. A carrier wave is also used as a medium for providing program data according to the present invention via a communication line.

1000 Color adjustment system 1 Color printer 2 Controller 3 Measuring instrument 10 Client PC
11 CPU
16 Storage unit 100 First LUT
200 Second LUT

Claims (22)

Color conversion for converting input image data into output CMYK values generated based on an output device profile indicating the relationship between input CMYK values in an output device and output color values indicating coordinates in a device-independent color space A color conversion step of obtaining output CMYK values from input image data using a table;
An input value adjustment table generated based on a difference between the output color value with respect to the input CMYK value specified from the standard profile in which the relationship between the input CMYK value and the output color value is determined in advance and the output device profile. An input value adjusting step for obtaining an adjusted CMYK value corresponding to a standard state from the output CMYK value obtained in the color conversion step, and a K component value from the adjusted CMYK value obtained in the input value adjusting step. And a component value decreasing step of obtaining a saved CMYK value by decreasing the sum of the component values of the adjusted CMYK value by decreasing the CMY component values corresponding to the K component value to be increased. Using the output value adjustment table generated by inverting the input / output values of the input value adjustment table, the component value decreasing step obtained in the step A color adjustment step having an output value adjustment step of about CMYK values to obtain the final CMYK value for outputting the image to the output device,
Only including,
In the component value reduction step, using the first saving conversion table for obtaining the output color value from the adjusted CMYK value generated based on the standard profile, the output color value from the adjusted CMYK value. And obtaining an increased K component value from the minimum value of the CMY component values in the adjusted CMYK value and the K component value in the adjusted CMYK value, and based on the first saving conversion table Output obtained from the increased K component value and the adjusted CMYK value using the second saving conversion table for obtaining the saving CMYK value from the K component value and the output color value generated A color adjustment method comprising a step of obtaining the saved CMYK value from a color value . 2. The color adjustment method according to claim 1 , wherein the second saving conversion table is set so that a total of the component values of the saving CMYK values does not exceed a predetermined upper limit value. For the sum of the CMYK component values in the input CMYK value input to the first saving conversion table exceeding the upper limit value, the sum of the CMYK component values in the input CMYK value is less than or equal to the upper limit value. A reduction rate is calculated from the sum of CMY component values in the input CMYK values and the sum of CMY component values obtained by subtracting K component values in the input CMYK values from the target values. The rate is applied to each CMY component value in the input CMYK value to convert it into a reduced input CMYK value, and the output color value and the K component value obtained based on the converted reduced input CMYK value By setting the second saving conversion table so that saving CMYK values can be obtained, the sum of the component values of the saving CMYK values does not exceed a predetermined upper limit value. Color adjustment method according to claim 2, characterized in that the sea urchin set. Includes savings setting process to set savings,
In the component value reduction step, in response to said savings set in savings setting step, the color adjustment according to the K component value is increased in any one of claim 1 to 3, characterized in that variable Method. Output selection for selecting which of the output CMYK value obtained in the color conversion step and the final CMYK value obtained in the color adjustment step is a CMYK value for causing the output device to output an image The method according to any one of claims 1 to 4 , further comprising a step. In the output selection step, when at least one component value of CMY in the output CMYK value obtained in the color conversion step is 0, the output CMYK value obtained in the color conversion step is used as the output device. The color adjustment method according to claim 5 , wherein CMYK values for outputting an image are used. In the output selection step, when the K component value in the output CMYK value obtained in the color conversion step is 0 and the minimum value among the CMY component values is less than or equal to a predetermined value, the color conversion step The color adjustment method according to claim 5 or 6 , wherein the output CMYK value obtained in step 1 is used as a CMYK value for causing the output device to output an image. An output device profile indicating a relationship between an input CMYK value in the output device and an output color value indicating coordinates in a device-independent color space, and from input image data generated based on the output device profile to an output CMYK value A storage unit for storing a color conversion table for conversion, and a standard profile in which a relationship between an input CMYK value and the output color value is predetermined;
An output value adjustment table is generated based on a difference of the output color value with respect to an input CMYK value specified from the standard profile and the output device profile, and an output in which input / output values of the input value adjustment table are inverted A value adjustment table is generated, an output CMYK value is obtained from input image data using the color conversion table, and an adjustment CMYK value corresponding to a standard state is obtained from the output CMYK value using the input value adjustment table. The total of the component values of the adjusted CMYK value is reduced by increasing the K component value from the adjusted CMYK value and decreasing the CMY component values corresponding to the increased K component value. A value is obtained, and an image is output from the saved CMYK value to the output device using the output value adjustment table. A control unit for acquiring the final CMYK value,
Equipped with a,
The control unit obtains the output color value from the adjusted CMYK value using the first saving conversion table for obtaining the output color value from the adjusted CMYK value generated based on the standard profile. Then, an increased K component value is obtained from the minimum value of the CMY component values in the adjusted CMYK value and the K component value in the adjusted CMYK value, and generated based on the first saving conversion table The output color value obtained from the increased K component value and the adjusted CMYK value using the second saving conversion table for obtaining the saved CMYK value from the K component value and the output color value The color adjusting device is characterized in that the saved CMYK value is obtained from 9. The color adjustment according to claim 8 , wherein the control unit generates the second saving conversion table such that a total of the component values of the saving CMYK values does not exceed a predetermined upper limit value. 10. apparatus. The control unit calculates the sum of the CMYK component values in the input CMYK value when the sum of the CMYK component values in the input CMYK value that is input to the first saving conversion table exceeds the upper limit value. It converts to a target value that is less than or equal to the upper limit value, and the reduction rate is calculated from the sum of CMY component values in the input CMYK values and the sum of CMY component values obtained by subtracting K component values in the input CMYK values from the target values Calculate and apply the reduction rate to each CMY component value in the input CMYK value to convert it into a reduced input CMYK value, and output color values obtained based on the converted reduced input CMYK values and K By generating the second saving conversion table so that the saving CMYK value is obtained from the component value, the sum of the component values of the saving CMYK value is a predetermined upper limit. The color adjustment device according to claim 9, characterized in that not exceed. The color control apparatus according to claim 8 , wherein the control unit sets a saving amount and varies a K component value to be increased according to the set saving amount. . Wherein the control unit, any one of claims 8-11, characterized in that selects whether the CMYK values for outputting the image either with the final CMYK value and the output CMYK values to the output device The color adjusting device according to item. The control unit, when at least one component value of CMY in the output CMYK value is 0, sets the output CMYK value as a CMYK value for causing the output device to output an image. Item 13. The color adjustment device according to Item 12 . The control unit causes the output device to output an image when the K component value in the output CMYK value is 0 and the minimum value among the CMY component values is equal to or less than a predetermined value. The color adjusting apparatus according to claim 12 , wherein the color adjusting apparatus uses a CMYK value for the purpose. Computer
A standard profile in which a relationship between an input CMYK value and an output color value indicating coordinates in a device-independent color space is predetermined, and an output device profile that indicates a relationship between the input CMYK value in the output device and the output color value An input value adjustment table is generated based on the difference of the output color value with respect to the input CMYK value specified from the above, and an output value adjustment table in which input / output values of the input value adjustment table are inverted is generated, and the output device An output CMYK value is obtained from the input image data using a color conversion table for converting the input image data into an output CMYK value generated based on the profile, and the output CMYK value is obtained using the input value adjustment table. get the adjustment CMYK values corresponding to the standard state from the said adjustment CMYK values, increasing the K component value In addition, the CMYK component value corresponding to the K component value to be increased is decreased to obtain a saved CMYK value in which the sum of the component values of the adjusted CMYK value is decreased, and the output value adjustment table is used. A color adjustment program for functioning as control means for obtaining a final CMYK value for causing the output device to output an image from the saved CMYK value ,
The control means obtains the output color value from the adjusted CMYK value using a first saving conversion table for obtaining the output color value from the adjusted CMYK value generated based on the standard profile. Then, an increased K component value is obtained from the minimum value of the CMY component values in the adjusted CMYK value and the K component value in the adjusted CMYK value, and generated based on the first saving conversion table The output color value obtained from the increased K component value and the adjusted CMYK value using the second saving conversion table for obtaining the saved CMYK value from the K component value and the output color value And obtaining the saved CMYK value. 16. The color adjustment according to claim 15 , wherein the control unit generates the second saving conversion table such that a total of the component values of the saving CMYK values does not exceed a predetermined upper limit value. program. The control means calculates the sum of the CMYK component values in the input CMYK value when the sum of the CMYK component values in the input CMYK value input to the first saving conversion table exceeds the upper limit value. It converts to a target value that is less than or equal to the upper limit value, and the reduction rate is calculated from the sum of CMY component values in the input CMYK value and the sum of CMY component values obtained by subtracting the K component value in the input CMYK value from the target value. Calculate and apply the reduction rate to each CMY component value in the input CMYK value to convert it into a reduced input CMYK value, and output color values obtained based on the converted reduced input CMYK values and K By generating the second saving conversion table so that the saving CMYK value can be obtained from the component value, the sum of the component values of the saving CMYK value is increased by a predetermined amount. Color adjustment program according to claim 16, he characterized in that it does not exceed the value. Said control means sets the savings, depending on the savings that are the setting, color adjustment program according to K component value to increase to any one of claims 15 to 17, characterized in that the variable . 19. The control unit according to claim 15 , wherein the control unit selects which of the output CMYK value and the final CMYK value is a CMYK value for causing the output device to output an image. The color adjustment program described in the item. The control means, wherein at least one component value of CMY at the output CMYK values when it is 0, characterized by the CMYK values for outputting the image the output CMYK values to the output device Item 20. The color adjustment program according to Item 19 . The control means causes the output device to output an image of the output CMYK value when the K component value in the output CMYK value is 0 and the minimum value among the CMY component values is not more than a predetermined value. 21. The color adjustment program according to claim 19 , wherein the color adjustment program is a CMYK value. A computer-readable medium storing the color adjustment program according to any one of claims 15 to 21 .

Images