JP6729098B2 - Color processing device, color processing system, and color processing program - Google Patents

Description

The present invention relates to a color processing device, a color processing system, and a color processing program.

Patent Document 1 discloses an image processing apparatus that causes a reading unit to read a predetermined document and sets appropriate processing parameters, and an input unit that reads the document in advance by the reading unit and inputs the obtained image data. A determination unit that determines whether the input image data is within the input range of the reading unit, and a setting unit that sets the processing parameter using the image data within the input range based on the result of the determination. An image processing apparatus characterized by having is disclosed.

In Patent Document 2, the first color information in the first color space and the first color information is output in the second color space when input to a color-adjusting unit that performs image color adjustment. It is output when the first related information in which the first output color information as a target to be associated is associated, and the first color information and the first color information are input to the color adjustment means. Relative information acquisition unit that acquires second related information that associates the second output color information in the second color space of the image, and the first color information that is used in the second related information An output unit that outputs the second color information in the first color space, which has a reduced number, to the color-adjusting means, and the color-receiving area when the second color information is input to the color-adjusting means. An output color information acquisition unit that acquires third output color information in the second color space output by the adjusting unit, and the second relation newly applied based on the third output color information. Based on the prediction unit that predicts information by predicting the second output color information, and the second related information and the first related information that are predicted, the target in the first color space is used. There is disclosed a color processing device, comprising: a conversion relationship creating unit that creates a conversion relationship for performing color adjustment of a color adjusting unit.

In Patent Document 3, a plurality of read data on a device-dependent color space generated by reading a plurality of color patches, a plurality of reference data on a device-independent color space for the plurality of color patches, and Receiving means for receiving a plurality of specific color component data representing a specific color component for each color patch in a plurality of color patches, and a plurality of read data, the plurality of reference data and the plurality of specific color component data , Conversion information in which the presence or absence or the amount of a specific color component included in each of the color patches is reflected as information for converting the input data in the device-dependent color space into the output data in the device-independent color space. An image processing device is disclosed, which comprises: conversion information creating means for creating.

In Patent Document 4, a reading unit reads a document, a unit that stores the read value, and a unit that stores a correction target value for correcting the color conversion table applied to the reading unit. A means for preparing a correction lookup table for converting an image signal converted from a device-dependent color space into a device-independent color space according to the reading means into a device-independent color space; and the stored read value. Means for correcting the value of the device-independent color space of the correction look-up table according to the stored target value; and means for updating the color conversion table using the corrected correction look-up table. The image processing apparatus is characterized in that the original is composed of at least patches smaller than the number of grid points of the correction look-up table, and the read value and the target value are obtained according to the patch. ing.

JP-A-09-006956 JP, 2005-119422, A JP, 2005-073152, A JP, 2010-193076, A

Conventionally, when performing color management of an image forming apparatus (so-called printer), a color conversion model for converting a color in a first space into a color in a second space is created in advance for each printer, and the color conversion model is used. The color may be managed. In this case, the color conversion model is preferably created by a printer that has been calibrated (color adjustment), but it may be created by a printer that has not been calibrated. In addition, the calibration target value may have been changed after the color conversion model was created.

Before and after the calibration by the printer, the gradation of the color, especially the gradation of the specific color (K color) may change. In that case, since the linearity of the gradation of the specific color (K color) is not guaranteed in the color conversion model, the accuracy of the color conversion decreases.

The present invention compares the color of the first space with the color of the second space as compared with the case where the density of the specific color in the color conversion model for converting the color of the first space into the color of the second space is not corrected. An object is to provide a color processing device, a color processing system, and a color processing program that can perform conversion with high accuracy.

The color processing device according to claim 1, wherein an acquisition unit that acquires first relationship information representing a relationship between a color in the first color space and a color in the second color space as a color conversion model, and K color in the color conversion model. The color value of the first color space is corrected by the correction unit that corrects the density of the K color of the color conversion model so that the characteristic value of C approaches the target characteristic value of the K color, and the corrected color conversion model. A conversion unit that converts the color into the color of the second color space.

According to a second aspect of the present invention, there is provided the color processing device according to the first aspect, wherein the correction unit is configured to determine the lightness of the K color in the first relational information and the color of the first color space obtained by measurement. The density of the K color in the color conversion model is corrected so as to approach the brightness of the K color in the second relationship information that represents the relationship with the color in the second color space.

The color processing apparatus according to claim 3, in the invention of claim 2, wherein the correction means, when correcting the color transformation model, the K color which represents the variation in the concentration of K color in a plurality of types of original color The density range is not corrected.

According to a fourth aspect of the present invention, in the color processing apparatus according to the first aspect, the correction means sets the color conversion model so that the density of the K color of the first relation information corresponds to a calibration target value. Correct the K color density .

Color processing apparatus according to claim 5, in the invention of claim 4, wherein said correcting means, said plurality of color density of the concentration of K color is different in the first relationship information, the plurality of color calibration The density of K color of the first relation information is corrected so as to correspond to the target value.

According to a sixth aspect of the present invention, in the color processing device according to any one of the first to fifth aspects, the lightness of the K color in the first relational information is the color of the first color space obtained by measurement. And a first correction method for correcting the density of K color in the color conversion model so as to approach the brightness of K color in the second relationship information that represents the relationship between the color of the second color space and the color of the second color space. the concentration of K color, so as to correspond to the target value of the calibration, a receiving means for receiving one of the selection of the second correction method for correcting the concentration of the K-color of the color conversion model, by the reception unit the accepted correction method setting means for setting a correction method by the correction means, further wherein the receiving means is selected by the user, either the first correction method and the second correction method accepting an correction method.

A color processing system according to a seventh aspect includes the color processing apparatus according to the second or sixth aspect , and a measuring unit that measures the color of the read image formed by the image forming apparatus that is the target of the color processing.

A color processing program according to claim 8 is a program for causing a computer to function as each unit that constitutes the color processing apparatus according to any one of claims 1 to 6 .

According to the inventions of claims 1, 7 and 8 , the color of the first space is compared with the case where the density of the K color in the color conversion model for converting the color of the first space into the color of the second space is not corrected. It is possible to accurately perform the color conversion for converting into the color of the second space.

According to the invention of claim 2, as compared with the case where the color conversion model is corrected without using the second relationship information indicating the relationship between the color of the first space and the color of the second space obtained by the measurement, The color conversion for converting the color of the first space into the color of the second space can be performed accurately.

According to the invention of claim 3, the value of K color in the first relationship information representing the relationship between the color of the first space and the color of the second space is compared with the case where the value is corrected in the entire range of the density of K color. As a result, it is possible to prevent the color accuracy from deteriorating due to the characteristics of each type of document.

According to the invention of claim 4, as compared with the case where the color conversion model is corrected without using the calibration target value, the color conversion for converting the color of the first space into the color of the second space is performed with high accuracy. be able to.

According to the invention of claim 5, compared with the case where the color conversion model is corrected without using the calibration target values of a plurality of colors having different densities of K color, the first space can be measured without performing the color measurement. It is possible to perform the color conversion for converting the color of the color into the color of the second space.

According to the invention of claim 6, it is possible to avoid changing the correction method each time color conversion is performed, as compared with the case where the K color correction method in the color conversion model is not fixed.

1 is a block diagram showing an overall configuration of a color processing system according to an embodiment. It is a block diagram showing a functional composition of a color processing device concerning an embodiment. 3 is a block diagram showing an electrical configuration of the color processing device according to the embodiment. FIG. 6 is a flowchart showing a program flow of a conversion data set creation process according to the embodiment. FIG. 6 is a schematic diagram for explaining a method of creating a conversion data set according to the embodiment. FIG. 6 is a schematic diagram for explaining a method of creating a measurement data set according to the embodiment. It is a schematic diagram which shows the relationship between conversion color data and measurement color data. An example of the relationship between Cin[%], the K density of conversion color data, and the K density of measured color data, and an example of the relationship between Cin[%] and Cout[%] of K color according to the embodiment will be described. It is a table. 6 is a graph showing an example of a relationship between Cin [%] of conversion color data and lightness L* according to the embodiment. 6 is a graph showing an example of the relationship between Cin [%] of measured color data and lightness L* according to the embodiment. 1 is a graph in which an example of the relationship between Cin[%] of conversion color data and lightness L* and an example of the relationship of Cin[%] of measurement color data and lightness L* are displayed in an overlapping manner. is there. 6 is a graph showing an example of a method of correcting the K color value of the conversion color data according to the embodiment. 9 is a graph showing an example of a relationship between Cin[%] and Cout[%] of K color as a conversion LUT according to the embodiment. 6 is a graph showing an example of a relationship between Kin Cin [%] and lightness L* according to the embodiment. 6 is a flowchart showing the flow of a program for color conversion processing according to the embodiment. It is a flow chart which shows the flow of the program of the setting processing concerning a 2nd embodiment. It is a flow chart which shows the flow of the program of the setting processing concerning a 3rd embodiment. The relationship between the Cin[%] of the K color after color conversion and the lightness L* when the K color value of the conversion color data is corrected by the color processing apparatus according to the embodiment, and the K color of the conversion color data 7 is a graph showing an example of the relationship between Cin[%] of K color after color conversion and lightness L* when the value is not corrected. The number of measured colors after color conversion, when the K color value of the conversion color data is corrected by the color processing device according to the embodiment and when the K color value of the conversion color data is not corrected, It is a table showing the average color difference, the maximum color difference of the top 95%, and the maximum color difference. The average color difference after color conversion when the K color value of the conversion color data is corrected by the color processing apparatus according to the embodiment and when the K color value of the conversion color data is not corrected, the top 95 It is a graph showing the maximum color difference of% and the maximum color difference.

Hereinafter, the color processing system according to the present embodiment will be described with reference to the accompanying drawings.

As shown in FIG. 1, the color processing system 1 according to the present embodiment includes a color processing device 2 described later and an image forming device 3 that forms an image on a sheet 4. Further, in the color processing system 1, the image formed on the sheet 4 by the image forming apparatus 3 (so-called scanner) 5 that is an example of a reading unit that reads the image formed on the sheet 4 by the image forming apparatus 3 and the image forming apparatus 3. It has a color measuring device 6 for measuring the color of an image. Examples of the color measuring device 6 include a spectrocolorimeter and an LED (light emitting diode) colorimeter.

As shown in FIG. 2, the color processing device 2 includes a read image creation unit 12, a read data acquisition unit 14, a correction unit 16, a color conversion unit 18, and a color processed data storage unit 22. The color processing data storage unit 22 also includes a calibration data storage unit 22a, a conversion color data storage unit 22b, and a corrected color data storage unit 22c.

As shown in FIG. 3, the color processing apparatus 2 according to the present embodiment has, for example, a CPU (Central Processing Unit) 30, a RAM (Random Access Memory) 32, and a ROM (Read Only Memory) 34 that stores various programs. It is composed of a computer device provided with. In the present embodiment, the CPU reads and executes a program stored in a storage unit such as a ROM or a hard disk, whereby the above hardware resources and the program cooperate with each other to realize the above-described functions. The computer device also includes a storage unit 36 such as a non-volatile memory that stores various information used for the processing of the CPU 30. The color processing data storage unit 22 is provided in the storage unit 36.

Further, the CPU 30 is connected to a communication line I/F (interface) unit 38 that inputs/outputs data to/from an external device connected to the color processing device 2. Further, the CPU 30 is connected to a keyboard, a mouse, etc. for inputting data, and an operation display unit 40 having a display, etc. for displaying data.

The calibration data storage unit 22a stores calibration data for performing calibration for each image forming apparatus 3. In this embodiment, as the calibration data, a plurality of sets of Cin [%] representing the density of the specific color (K color) and the target value of the lightness L* are stored. When the image forming apparatus 3 is calibrated, Cin[%] is corrected such that the K color of Cin[%] has the lightness L* which is the target value.

The conversion color data storage unit 22b stores conversion color data, which is an example of the first relationship information, as a color conversion model. The conversion color data is information in which RGB values, K values, and Lab values related to a large number (for example, 1500 points) of colors are associated with each other. When the image forming apparatus 3 forms an image, a color-adjusted image is formed using the conversion color data.

Here, the flow of the conversion color data creation process in which the color processing device 2 creates the conversion color data will be described with reference to the flowchart shown in FIG.

The conversion color data may be created using an image forming apparatus that is the target of color processing or an image forming apparatus that is not the target of color processing. Further, the conversion color data may be created using a paper of a type that is a target of color processing or may be created using a paper of a type that is not a target of color processing.

In step S101, the CPU 30 acquires the RGB data of the RGB space, which is an example of the first color space, obtained by reading the plurality of reading images formed by the image forming apparatus 3. The read image 42 is an image for adjusting the color for each image forming apparatus or each type of paper. In the present embodiment, as shown in FIG. 5, the image forming apparatus 3 forms a pattern image 42A in which a plurality of reading images 42 having different colors are arranged in a grid on the paper 4. In addition, the image reading device 5 creates the RGB data 44A of the pattern image 42A by reading the formed pattern image 42A. Further, the color processing device 2 acquires the rgb data 44A of the pattern image 42a from the image reading device 5.

In step S103, the CPU 30 obtains Lab data in the Lab space, which is an example of the second color space, obtained by measuring the color of the reading image formed by the image forming apparatus 3. In the present embodiment, as shown in FIG. 5, the image forming apparatus 3 forms the pattern image 42A on the paper 4. Further, the color measuring device 6 creates the Lab data 46A of the pattern image 42A by measuring the color of the formed pattern image 42A. Further, the color processing device 2 acquires the Lab data 46A of the pattern image 42a from the color measuring device 6.

In step S<b>105, the CPU 30 causes the information indicating the drawing position of each reading image 42 included in the pattern image 42</b>A and the density (K value) of the specific color (K color in this embodiment) of each reading image 42. The specific color information 48A including the information indicating) is acquired.

In step S107, the CPU 30 selects one of the read images 42 included in the pattern image 42A. In the present embodiment, each of the reading images 42 arranged in a grid pattern is sequentially selected from the upper left.

In step S109, the CPU 30 determines whether or not the reading image 42 selected in step S107 includes K color based on the specific color information 48A acquired in step S105. If it is determined in step S109 that the K color is included (S109, Y), the process proceeds to step S111, and if it is determined that the K color is not included (S109, N), the process proceeds to step S113.

In step S111, the CPU 30 includes, in the conversion data set A, information in which the RGB value of the selected reading image, the K value of the selected reading image, and the Lab value of the selected reading image are associated with each other. Control goes to step S115. As shown in FIG. 5, a conversion data set A in which RGBK data 441A including K values in RGB data including K colors and Lab data 461A including K colors are associated with each other is generated.

In step S113, the CPU 30 includes, in the conversion data set B, information in which the RGB value and the Lab value of the reading image selected in step S107 are associated with each other, and the process proceeds to step S115. As shown in FIG. 5, a conversion data set B is generated in which RGB data 442A that does not include K color and Lab data 462A that does not include K color are associated with each other.

In step S115, it is determined whether or not there is an unprocessed reading image 42, that is, the reading image 42 that has not undergone the processes of steps S105 to S113. If it is determined in step S115 that there is an unprocessed read image 42 (S115, Y), the process proceeds to step S105, the unprocessed read image 42 is selected in step S105, and the processes of steps S107 to S113 are performed. .. If it is determined in step S115 that there is no unprocessed read image 42 (N in S115), the process proceeds to step S117.

In step S117, the CPU 30 stores the conversion data set A and the conversion data set B as conversion color data in the conversion color data storage unit 22b, and ends the execution of the program for the conversion color data creation process.

The conversion color data storage unit 22b stores in advance the conversion color data created in this way. The conversion color data is used, for example, as a color conversion model when converting RGBK data into Lab data.

Here, when the color processing apparatus 2 causes the image forming apparatus 3 to form an image, the color of the formed image is the original image depending on the type of the image forming apparatus 3 and the type of paper to be image-formed. It may be different from the color of. Therefore, when the reading image for adjusting the color is prepared in advance, the color processing device 2 changes the prepared reading image to the color of the image obtained by reading the image with the image reading device 5. Adjust the color based on. Further, when the reading image is not prepared in advance, the color processing apparatus 2 causes the image forming apparatus 3 to form the reading image, and the formed reading image is read by the image reading apparatus 5 to be obtained. Adjust the color based on the color of the image.

The image forming unit for reading 12 causes the image forming apparatus 3 to form an image and adjusts the color based on the color of the image obtained by reading the formed image with the image reading apparatus 5, as shown in FIG. As described above, the correction pattern image 42B in which the reading images 42 of a plurality of colors are arranged in a grid pattern is created. At this time, the read image creation unit 12 also creates specific color information 48B including information indicating the density of the K color of each read image 42. Further, the read image creating unit 12 sends the image data indicating the created correction pattern image 42B to the image forming apparatus 3. The image forming apparatus 3 forms the correction pattern image 42B on the sheet 4 based on the received image data. The correction pattern image 42B may be composed of the read image 42 of one color.

In addition, the reading image creating unit 12 reads the correction pattern image of the reading image of one color determined in advance for performing the calibration of the image forming apparatus 3 or the reading of a plurality of predetermined colors having different densities of K colors. A correction pattern image in which the use images are arranged in a grid is created. In this case as well, similarly, the read image creating unit 12 also creates specific color information including information indicating the density of K color of each read image. Further, the read image creating unit 12 sends image data indicating the created correction pattern image to the image forming apparatus 3. The image forming apparatus 3 forms a correction pattern image on the sheet 4 based on the received image data.

The read data acquisition unit 14 acquires the RGB data 44B in which the correction pattern image 42B formed on the paper 4 is read by the image reading device 5.

The read data acquisition unit 14 uses the image data obtained by converting each of the RGB data 44B into the color of the Lab space by using the color conversion model that converts the color of the RGB space into the color of the Lab space. Convert to some Lab data 46B. In the present embodiment, the correspondence relationship between each color in the RGB space and each color in the Lab space is obtained in advance using the plurality of reading images 42, and the color conversion model based on this correspondence relationship is stored in the color processing data storage unit 22. doing. Then, the read data acquisition unit 14 uses the stored color conversion model to create Lab data 46B in which each color of the RGB data is converted to a color in the Lab space.

The read data acquisition unit 14 also sets the measurement data set C in which the RGBK data 461B including the K value to the RGB data 441B including the K color and the Lab data 461B including the K color are associated with each other, as an example of the second relationship information. Is created as measurement color data. The read data acquisition unit 14 also creates a measurement data set D in which the RGB data 442B that does not include K color and the Lab data 462B that does not include K color are associated with each other.

The correction unit 16 determines that the characteristic value of K color (for example, lightness, density, color difference, etc.) of the conversion color data stored in the conversion color data storage unit 22b is the measurement color created by the read data acquisition unit 14. The K color value in the conversion color data is converted so as to approach the K color characteristic value of the data. Further, the correction unit 16 causes the post-correction color data storage unit 22c to store the conversion color data obtained by converting the K color value as post-correction color data.

That is, as shown in FIG. 7, when the K color values of the colors 52A, 52B... In the conversion color data and the K color values of the corresponding colors 54A, 54B. There is. In such a case, it is preferable that the K color value when forming an image is set based on the K color value in the measurement color data obtained by the measurement. Further, when the difference between the K color value in the conversion color data and the K color value in the measurement color data is calculated, the K color Cin of the conversion color data and the K color Cin of the measurement color data are different. Then, the difference between the RGB values includes an error. Therefore, it is desirable to align the K color value corresponding to the K color Cin of the conversion color data and the K color value corresponding to the K color Cin of the measurement color data.

At this time, it is desirable to directly obtain the K color value of the reading image 42 included in the correction pattern image 42B and create the color conversion model in the RGBK density state. However, the K color value of the reading image 42 is desired. It is difficult to ask directly. Therefore, in the present embodiment, the K color value corresponding to the K color Cin of the conversion color data and the K color value corresponding to the K color Cin of the measurement color data are aligned with a single color density.

As an example, FIG. 8 is a table 56A showing the relationship between the lightness L* of K in the conversion color data for Cin of K color and the lightness L* of K in the measurement color data for Cin of K color, and FIG. Table 56B showing the relationship between Cin and Cout is shown. Further, FIG. 9A shows a graph showing the relationship between the Cin of K color and the lightness L* of K in the conversion color data. Further, FIG. 9B shows a graph showing the relationship between Cin of K color and lightness L* of K in the measured color data. Further, FIG. 9C shows a graph in which the graph of FIG. 9A and the graph of FIG. 9B are superimposed.

According to the example shown in FIG. 9C, as the K color Cin becomes higher in the range where the K color Cin is about 10% or more, the K color Cin in the measurement color data is for conversion corresponding to the same lightness L*. It is higher than Cin of K in the color data. In this case, for the K color Cin, the K color having a higher density than originally is extracted from the conversion color data.

Therefore, in the present embodiment, as shown in FIG. 10, the Cin of K color in the conversion color data corresponds to the characteristic value of K color in the Cin of the K color (here, the lightness L*), and the measured color A color conversion model is created after conversion to K color Cin in the data. For example, referring to FIG. 10, since the lightness L* of Cin 80% in the conversion color data corresponds to Cin 89% in the measurement color data, Cin of the conversion color data is converted from 80% to 89%. In this way, each Cin value in the conversion color data is converted into Cout based on Cin in the measurement color data. The correction method for correcting the K color value corresponds to the correction method A described later.

When Cin in the measured color data, which corresponds to the lightness L* of Cin in the conversion color data, exceeds 100%, Cin in the conversion color data is converted to 100%.

Further, in the present embodiment, the Cin of the conversion color data is converted so that the lightness L* of Cin in the conversion color data and the lightness L* of Cin in the measurement color data are equivalent, but the present invention is not limited to this. .. The Cin of the conversion color data may be converted so that the Cin lightness L* of the conversion color data approaches the Cin lightness L* of the measurement color data.

Further, in the area on the paper white (original color) side of the paper 4 (area where the K density is low), the value of K color is low, and the value of K color greatly varies depending on the characteristics of each type of paper. Therefore, within the range from the lowest value (0%) of Cin of the conversion color data to the predetermined control point (the range showing the variation for each color type of the document), Cin is not converted and Cout is directly used. And It should be noted that the control point mentioned here represents the maximum value of Cin of the colors of a plurality of types of originals that may be used in the image forming apparatus 3, and in the present embodiment, the control point is Cin=30%. As a result, by correcting the K color, it is possible to prevent the color accuracy from decreasing due to the characteristics of each type of the paper 4.

FIG. 11 shows, as a conversion LUT, a graph showing the relationship between Cin and Cout obtained by converting each Cin value in the conversion color data based on Cin in the measurement color data. The correction unit 16 converts the K color value (Cin) of the conversion color data into the K′ value (Cout) based on the conversion LUT as the corrected color data, and outputs the corrected color data storage unit 22c. Memorize.

On the other hand, as shown in FIG. 12 as an example, the lightness L* for Cin [%] of K color in the measurement color data is compared with the target value of lightness L* for Cin of K color (represented by a dotted line in FIG. 12). , There may be deviation. In consideration of such a case, in a general image forming apparatus, the color is adjusted so that the density of K color in the formed image corresponds to the calibration target value. Therefore, in the present embodiment, the color processing device 2 adjusts the Cin of the K color so that the density of the K color in the color conversion model corresponds to the target value of the calibration, so that the image forming device 3 forms the image. Adjust the image color. The correction method for correcting the K color value corresponds to the correction method B described later.

As described above, the color processing device 2 uses one of the following correction methods (correction method A) and (correction method B) to correct the K color in the color conversion model stored in the conversion color data storage unit 22b. Make a correction.

(Correction Method A; First Correction Method) The K color value of the conversion color data is corrected based on the measurement color data obtained by reading the correction pattern image 42B in which the plurality of reading images 42 are arranged. ..
(Correction Method B; Second Correction Method) Assuming that the image forming apparatus 3 is calibrated, conversion is performed based on the target value of the lightness L* corresponding to each K color value in the calibration. The K color value of the working color data is corrected.

The color conversion unit 18 generates a color conversion model based on the measured color data created by the read data acquisition unit 14 and the corrected color data stored in the corrected color data storage unit 22c. In the present embodiment, when color conversion is performed using the corrected color data, the color conversion is performed based on the RGBK-Lab value of the color most similar to the conversion source color in the corrected color data, but the present invention is not limited to this. Absent. For example, a conversion formula may be created from the corrected color data with the information of the color of the conversion source as an argument, and the color conversion may be performed based on the created conversion formula.

Next, a flow in which the color processing device 2 according to the present embodiment performs color conversion processing will be described with reference to the flowchart shown in FIG.

In the present embodiment, the program for color conversion processing is stored in the storage unit 36 in advance, but the present invention is not limited to this. For example, the color conversion processing program may be received from an external device via the communication line I/F unit 38 and executed. Further, the color conversion processing may be executed by reading a program for the color conversion processing recorded on a recording medium such as a CD-ROM with a CD-ROM drive or the like.

In the present embodiment, the color conversion processing program is executed when an execution instruction is input by the user operating the operation display unit 40. However, the execution timing is not limited to this, and may be executed at the timing when the image forming apparatus 3 is activated, for example.

In step S201, the correction unit 16 acquires the color conversion model by reading the conversion color data from the conversion color data storage unit 22b.

In step S203, the correction unit 16 determines whether or not the number of K-color single-color reading images 42 among the reading images 42 used to create the measurement color data is equal to or greater than a predetermined threshold value (for example, three). Determine whether. When it is determined in step S203 that the number of K-color single-color reading images 42 is equal to or larger than the threshold value (S203, Y), the process proceeds to step S205, and it is determined that the number of K-color single-color reading images 42 is less than the threshold value. If yes (S203, N), the process proceeds to step S207.

In step S205, the correction unit 16 corrects the K color value in the conversion color data acquired as the color conversion model by the correction method described above (correction method A), and then corrects the corrected conversion color data. The color data after correction is stored in the corrected color data storage unit 22c.

In step S207, the correction unit 16 corrects the K color value in the conversion color data acquired as the color conversion model by the correction method described above (correction method B), and then corrects the corrected conversion color data. The color data after correction is stored in the corrected color data storage unit 22c.

In step S209, the color conversion unit 18 performs color conversion based on the corrected color data stored in the corrected color data storage unit 22c, and the execution of the program for the main color conversion process ends.

As described above, in the present embodiment, the first relationship information indicating the relationship between the color of the first color space and the color of the second color space is acquired as the color conversion model, and the characteristic value of the specific color in the color conversion model is The color conversion model is corrected so as to approach the target characteristic value of the specific color. Further, in this embodiment, the color of the first color space is converted to the color of the second color space by the corrected color conversion model. As a result, even when the color conversion model is created before the calibration of the image forming apparatus 3, the K color can be appropriately corrected, and the accuracy of the color of the image formed on the paper 4 is improved. To do.

[Second Embodiment]

Next, the color processing system 1 according to the second embodiment will be described.

In the first embodiment, when any one of (correction method A) and (correction method B) is selected in accordance with the number of K single-color reading images 42 used to create the measurement color data I explained. On the other hand, in the second embodiment, (correction method A) is performed according to whether or not the K-color Cin of the K-color single-color reading image 42 is fixed and the number of K-color single-color reading images 42. A case will be described in which any of the correction methods (1) and (correction method B) is selected.

As shown in FIGS. 1 and 2, the configuration of the color processing system 1 according to the second embodiment is the same as that of the color processing system 1 according to the first embodiment. Therefore, the description of each component is omitted here.

Next, a flow in which the color processing device 2 according to the present embodiment performs the setting process will be described with reference to the flowchart shown in FIG.

In the present embodiment, the setting processing program is stored in the storage unit 36 in advance, but the present invention is not limited to this. For example, the setting processing program may be received from an external device via the communication line I/F unit 38 and executed. Further, the setting process may be executed by reading a setting process program recorded on a recording medium such as a CD-ROM with a CD-ROM drive or the like.

In the present embodiment, the setting processing program is executed when an execution instruction is input by the user operating the operation display unit 40. However, the execution timing is not limited to this, and may be executed at the timing when the image forming apparatus 3 is activated, for example.

In step S301, the correction unit 16 determines whether the Cin of the K-color single-color reading image 42 is fixed. When it is determined in step S301 that the Cin of the K-color single-color reading image 42 is fixed (S301, Y), the process proceeds to step S303, and the Cin of the K-color single-color reading image 42 is not fixed. If determined (S301, N), the process proceeds to step S307.

In step S303, the correction unit 16 determines whether or not the number of K-color single-color reading images 42 is equal to or larger than a predetermined threshold value (for example, three). It should be noted that the predetermined threshold value here may be any number as long as the gradation characteristic of K color is obtained. If it is determined in step S303 that the number of K-color single-color reading images 42 is equal to or greater than the threshold value (S303, Y), the process proceeds to step S305, and it is determined that the number of K-color single-color reading images 42 is less than the threshold value. If so (S303, N), the process proceeds to step S307.

In step S305, the correction unit 16 sets the correction method by the correction unit 16 to (correction method A), and ends the execution of the program for this setting processing. At this time, the correction unit 16 causes the color processing data storage unit 22 to store information indicating that the correction method by the correction unit 16 is set to (correction method A), for example. When the correction unit 16 corrects the K color of the conversion color data, the correction method (correction method A) is used based on the information stored in the color processing data storage unit 22.

In step S307, the correction unit 16 sets the correction method by the correction unit 16 to (correction method B), and ends the execution of the program for this setting processing. At this time, the correction unit 16 causes the color processing data storage unit 22 to store information indicating that the correction method by the correction unit 16 is set to (correction method B), for example. When the correction unit 16 corrects the K color of the conversion color data, the correction method (correction method B) is used based on the information stored in the color processing data storage unit 22.

As described above, in the present embodiment, when the density of the K color of the K-color single-color reading image 42 is not fixed in advance, (correction method B) is set as the correction method by the correction unit 16. When the number of K-color single-color reading images 42 is equal to or larger than a predetermined threshold value, (correction method A) is set as a correction method by the correction unit 16. This appropriately sets the K color correction method when performing color conversion, and avoids changing the correction method each time color conversion is performed.

[Third Embodiment]

Next, the color processing system 1 according to the third embodiment will be described.

In the second embodiment described above, (correction method A) and (correction method A) depending on whether or not the K-color Cin of the K-color single-color reading image 42 is fixed and the number of K-color single-color reading images 42. The case where any one of the correction methods B) is selected has been described. On the other hand, in the third embodiment, a case where a correction method is selected according to the correction method designated by the user will be described.

As shown in FIGS. 1 and 2, the configuration of the color processing system 1 according to the second embodiment is the same as that of the color processing system 1 according to the first embodiment. Therefore, the description of each component is omitted here.

Next, a flow in which the color processing device 2 according to the present embodiment performs the setting process will be described with reference to the flowchart shown in FIG.

In the present embodiment, the setting processing program is stored in the storage unit 36 in advance, but the present invention is not limited to this. For example, the setting processing program may be received from an external device via the communication line I/F unit 38 and executed. Further, the setting process may be executed by reading a setting process program recorded on a recording medium such as a CD-ROM with a CD-ROM drive or the like.

In the present embodiment, the setting processing program is executed when an execution instruction is input by the user operating the operation display unit 40. However, the execution timing is not limited to this, and may be executed at the timing when the image forming apparatus 3 is activated, for example.

In step S401, the correction unit 16 causes the operation display unit 40 to display a selection screen for selecting either the correction method (correction method A) or the correction method (correction method B). The user selects one of the correction method (correction method A) and the correction method (correction method B) using the operation display unit 40 while referring to the displayed selection screen.

In step S403, the correction unit 16 determines whether or not the correction method (correction method A) is selected by the user. When it is determined that the correction method of (correction method A) is selected in step S403 (S403, Y), the process proceeds to step S405, and when it is determined that the correction method of (correction method B) is selected (S403, N) Moves to step S407.

In step S405, the correction unit 16 sets the correction method by the correction unit 16 to (correction method A), and ends the execution of the program for this setting processing. At this time, the correction unit 16 causes the color processing data storage unit 22 to store information indicating that the correction method by the correction unit 16 is set to (correction method A), for example. When the correction unit 16 corrects the K color of the conversion color data, (correction method A) is used as the correction method based on the information stored in the color processing data storage unit 22.

In step S407, the correction unit 16 sets the correction method by the correction unit 16 to (correction method B), and ends the execution of the program for this setting processing. At this time, the correction unit 16 causes the color processing data storage unit 22 to store information indicating that the correction method by the correction unit 16 is set to (correction method B), for example. When the correction unit 16 corrects the K color of the conversion color data, (correction method B) is used as the correction method based on the information stored in the color processing data storage unit 22.

As described above, in this embodiment, the color conversion model is corrected (correction method A) so that the characteristic value of K color in the conversion color data approaches the characteristic value of K color in the measurement color data. Any selection of correcting the color conversion model (correction method B) so that the K color characteristic value of the color data corresponds to the calibration target value is accepted. Further, in the present embodiment, the accepted correction method is set as the correction method by the correction unit 16. This avoids changing the K color correction method each time color conversion is performed.

FIG. 16 shows the relationship between the Cin[%] of the K color after color conversion and the lightness L* when the K color value of the conversion color data is corrected by the color processing device 2 according to this embodiment, and The relationship between the Cin [%] of the K color after color conversion and the lightness L* when the K color value of the color data is not corrected is shown. As an example, as shown in FIG. 16, when the K color value of the conversion color data is not corrected, the lightness L* is in the range of 20% to 90% of Cin[%] of the K color. It deviates from the target value. On the other hand, when the K color value of the conversion color data is corrected, the lightness L* at each Cin [%] of the K color shows a value equivalent to the target value.

FIG. 17 shows color measurement when the color processing device 2 according to the present embodiment corrects the K color value of the conversion color data and when the K color value of the conversion color data is not corrected. A table showing the number, the average color difference after color conversion, the maximum color difference of the top 95%, and the maximum color difference is shown. In addition, FIG. 18 shows the color when the K color value of the conversion color data is corrected by the color processing device 2 according to the present embodiment and when the K color value of the conversion color data is not corrected. The graphs showing the average color difference after conversion, the maximum color difference of the top 95%, and the maximum color difference are shown. The color difference here is a color difference with respect to the target value of the lightness L* corresponding to each K color value.

As an example, as shown in FIGS. 17 and 18, the number of measured colors is 391, and the average color difference when the K color value of the conversion color data is corrected is 0.76, while the average color difference is 0.76. The average color difference when the K value of the color data was not corrected was 0.86. Further, when the K color value of the conversion color data is corrected, the maximum color difference of the upper 95% where the color difference is small is 1.72, whereas the K color value of the conversion color data is not corrected. In this case, the maximum color difference of the top 95% with less color difference was 2.30. The maximum color difference when the K color value of the conversion color data was corrected was 4.31, whereas the maximum color difference when the K color value of the conversion color data was not corrected was 6.31. It was 95. Thus, the average color difference and the maximum color difference when the K color value of the conversion color data is corrected are compared with the average color difference and the maximum color difference when the K color value of the conversion color data is not corrected. , You can see that it is getting smaller.

In the present embodiment, the case where the color processing device 2, the image forming device 3, the image reading device 5, and the color measuring device 6 are separately provided has been described, but the present invention is not limited to this. For example, the present invention is also applied to a color processing system in which the color processing device 2, the image forming device 3, the image reading device 5, and the color measuring device 6 are integrally formed. The present invention is also applied to a color processing system in which the color processing device 2, the image forming device 3, and the image reading device 5 are integrally formed, and the color measuring device 6 is connected to the color processing device 2. It

1 color processing system 2 color processing device 3 image forming device 4 paper 5 image reading device 6 color measuring device 12 image forming unit for reading 14 read data acquisition unit 16 correction unit 18 color conversion unit 22 color processing data storage unit 22b calibration data Storage unit 22b Conversion color data storage unit 22c Corrected color data storage unit 30 CPU
32 ROM
34 RAM
36 storage unit 38 communication line I/F unit 40 operation display unit

Claims (8)

An acquisition unit that acquires, as a color conversion model, first relationship information representing a relationship between a color in the first color space and a color in the second color space;
And correction means characteristic value of K color, to correct the concentration of the K-color of the color transformation model to approach the characteristic value of the K color as a target in the color transformation model,
Conversion means for converting the color of the first color space into the color of the second color space by the corrected color conversion model;
Color processing device equipped with. Said correction means, the lightness of K color in the first relationship information, obtained by measuring, K color in the second relationship information indicating the relationship between the color of said second color space of the first color space The color processing apparatus according to claim 1, wherein the density of K color of the color conversion model is corrected so as to approach the brightness of the color conversion model. The color processing apparatus according to claim 2, wherein the correction unit, when correcting the color conversion model, does not correct a range of K- color densities representing variations in K- color densities among colors of a plurality of types of originals. Wherein the correction means, the concentration of K color of the first relationship information, so as to correspond to the target value of the calibration, the color processing apparatus according to claim 1, wherein correcting the concentration of the K-color of the color transformation model. Said correction means, said plurality of color density of the concentration of K color is different in the first relationship information, so as to correspond to the target value of the calibration of the plurality of colors, the concentration of K color of the first relationship information The color processing apparatus according to claim 4, wherein The lightness of K color in the first relationship information approaches the lightness of K color in the second relationship information, which is obtained by measurement and represents the relationship between the color of the first color space and the color of the second color space. in a first correction method of correcting the density of the K-color of the color transformation model, the concentration of K color of the first relationship information, so as to correspond to the target value of the calibration, the K color of the color transformation model Accepting means for accepting any one of the selection of the second correction method for correcting the density of
Setting means for setting the correction method received by the receiving means as a correction method by the correction means;
Further equipped with ,
The reception unit receives any one of the first correction method and the second correction method selected by the user.
The color processing device according to claim 1. A color processing device according to claim 2 or 6 ,
Measuring means for measuring the color of the read image formed by the image forming apparatus to be subjected to color processing;
Color processing system with. Computer, according to claim 1-6 or color processing program for causing to function as each means of a color processing apparatus according to one of.

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