JP6809163B2 - Color processing equipment, image forming equipment and image forming system - Google Patents

Description

The present invention relates to a color processing apparatus, an image forming apparatus, and an image forming system.

In recent years, the printing market has been gradually shifting from offset printing machines to on-demand digital printing machines. Reprinting is one of the use cases for on-demand printers. Then, there are cases where a large number of copies are printed by an offset printing machine and then reprinted by a small number of copies by an on-demand printer, and cases where reprinting is performed only by an on-demand printer without using an offset printing machine.
In order to match the color of the printed matter output in the past with the printed matter at the time of reprinting at the time of such reprinting, the color patch printed in the past is measured to create a color conversion profile, or the past print output conditions ( It is necessary to output under the same conditions as the color conversion profile settings).

Patent Document 1 describes an alignment means for aligning the first output image data and the original image data, the second output image data and the original image data, and the first color component value associative data. , And the color component value mapping means for generating the second color component value mapping data, the color tone conversion parameter determining means for generating the color tone conversion parameter for converting the color tone, and the manuscript image data by the color tone conversion parameter. An image processing apparatus including a color tone conversion means for converting a pixel value of the above is disclosed.

Japanese Unexamined Patent Publication No. 2013-30996

The present invention creates a conversion relationship with higher accuracy even if there is an error or misalignment due to color conversion in creating a conversion relationship for matching the color of the printed matter output from the image forming means to a desired color. The purpose is.

The invention according to claim 1 is a color data acquisition unit that acquires color data of a first image output by a first image forming means based on image data, and the image data and the acquired color data. For each, a main color range extraction unit that extracts the main color range as the color range of the main color, which is the main color used, and a specific area on the image are extracted as a region group based on the main color range. Creating a first correspondence relationship by associating the region group extraction unit with the main color ranges of the image data and the color data to create a first correspondence relationship which is a correspondence relationship between the image data and the color data. A color processing apparatus comprising a unit and, wherein the image data and the color data in the area group are used for creating the first correspondence relationship in the first correspondence relation creation unit. ..
The invention according to claim 2 is the first aspect of the invention, based on the similarity of the characteristics of the pixels included in the main color range extracted for each of the image data and the acquired color data. The color processing apparatus according to claim 1, wherein a main color range used for creating a correspondence is determined.
The invention according to claim 3 is characterized in that the main color range extraction unit determines the main color range of the color data based on the number of pixels included in the main color range of the image data. Item 2. The color processing apparatus according to item 1 or 2.
The invention according to claim 4 is based on the image data from the first correspondence relationship and the second correspondence relationship regarding the second image forming means corresponding to the first correspondence relationship. A conversion relationship creating unit that creates a conversion relationship for adjusting the color of the second image forming means so that the color of the second image output by the image forming means of the above is the color of the first image. The color processing apparatus according to any one of claims 1 to 3 , characterized in that it has.
In the invention according to claim 5 , in the first correspondence relationship, the image data and the acquired color data of the first image are applied to the first correspondence relationship candidate prepared in advance. The color processing apparatus according to any one of claims 1 to 4 , wherein the color processing apparatus is created by matching.
The invention according to claim 6 is a color data acquisition unit that acquires color data of a first image output by a first image forming means based on image data, and the image data and the acquired color data. For each, the main color range extraction unit that extracts the main color range as the color range of the main color, which is the main color used, is associated with the main color range of the image data and the color data, and the image data is linked. A first correspondence relationship creating unit that creates a first correspondence relationship that is a correspondence relationship between the color data and the color data, and the main color range extraction unit includes each of the image data and the acquired color data. The color processing apparatus is characterized in that the main color range used for creating the first correspondence is determined from the similarity of the number of pixels included in the extracted main color range.
The invention according to claim 7 is a second image forming means for forming an image on a recording material based on image data, and a color adjusting means for adjusting the color of an image formed by the second image forming means. A conversion relationship creating means for creating a conversion relationship used for performing color adjustment by the color adjusting means, and the conversion relationship creating means outputs by the first image forming means based on the image data. For each of the color data acquisition unit that acquires the color data of the first image and the acquired image data and the acquired color data, the main color range is extracted as the color range of the main color that is mainly used. The main color range extraction unit is associated with the region group extraction unit that extracts a specific region on the image as a region group based on the main color range, and the main color ranges of the image data and the color data. , The first correspondence creating unit that creates the first correspondence that is the correspondence between the image data and the color data, the first correspondence, and the first that corresponds to the first correspondence. From the second correspondence relationship with respect to the second image forming means, the color of the second image output by the second image forming means based on the image data becomes the color of the first image. A conversion relationship creating unit that creates a conversion relationship that adjusts the color of the second image forming means is provided , and the image data and the color data in the region group are produced by the first correspondence relationship creating unit. It is an image forming apparatus characterized in that it is used to create a correspondence between .
The invention according to claim 8 comprises a first image forming means for forming an image on a recording material based on image data, and a second image forming means for forming an image on a recording material based on the image data. A color adjusting means for adjusting the color of an image formed by the second image forming means and a conversion relationship creating means for creating a conversion relationship used for performing the color adjustment with the color adjusting means are provided. The conversion relationship creating means includes a color data acquisition unit that acquires color data of the first image output by the first image forming means based on the image data, and the image data and the acquired color data. For each, a main color range extraction unit that extracts the main color range as the color range of the main color, which is the main color used, and a specific area on the image are extracted as a region group based on the main color range. Creating a first correspondence relationship by associating the region group extraction unit with the main color ranges of the image data and the color data to create a first correspondence relationship which is a correspondence relationship between the image data and the color data. From the second correspondence relationship between the unit, the first correspondence relationship, and the second image forming means corresponding to the first correspondence relationship, the second image forming means is used based on the image data. The area includes a conversion relationship creating unit that creates a conversion relationship that adjusts the color of the second image forming means so that the color of the output second image becomes the color of the first image. The image forming system is characterized in that the image data and the color data in the group are used by the first correspondence creating unit to create the first correspondence .

According to the invention of claim 1, in creating a conversion relationship for matching the color of the printed matter output from the image forming means to the desired color, the accuracy is higher even if there is an error or misalignment due to the color conversion. A color processing apparatus capable of creating a conversion relationship can be provided. In addition, it becomes easier to grasp the color difference between the first image and the second image.
According to the invention of claim 2, the first correspondence relationship can be obtained more accurately, and a conversion relationship with higher accuracy can be created.
According to the invention of claim 3, it becomes easier to associate the main color ranges of the image data and the color data.
According to the invention of claim 4 , based on the printed matter output from the first image forming means and the image data, the color of the printed matter output from the first image forming means is matched, and the second image forming means is used. Printed matter can be output.
According to the invention of claim 5 , the accuracy of the first correspondence is further improved.
According to the invention of claim 7, in creating a conversion relationship for matching the color of the printed matter output from the image forming means with the desired color, the accuracy is higher even if there is an error or misalignment due to the color conversion. An image forming apparatus capable of creating a transformation relationship can be provided. In addition, it becomes easier to grasp the color difference between the first image and the second image.
According to the invention of claim 8, it is possible to provide an image forming system capable of performing color adjustment even if the user does not have specialized skills. In addition, it becomes easier to grasp the color difference between the first image and the second image.

It is a figure which shows an example of the whole structure of the image formation system which concerns on this embodiment. It is an external view of the image forming apparatus which concerns on this embodiment. It is a figure which shows the internal structure of the image forming apparatus which concerns on this embodiment. It is a block diagram which shows the signal processing system in a control device. It is a block diagram explaining the functional structure of the color processing part in 1st Embodiment. (A) to (d) are diagrams showing a method in which a main color range extraction unit and a main color range extraction unit extract a main color range. (A) to (d) are diagrams for explaining Step 2 when the first correspondence creating unit creates the first correspondence. In the first embodiment, it is the flowchart explaining the procedure at the time of performing the color adjustment for outputting the image which matched the color of the image forming apparatus with an image forming apparatus. (A) to (i) are diagrams showing the actual processing when the image forming apparatus performs color adjustment for outputting an image matching the color of the image forming apparatus. It is a block diagram explaining the functional structure of the color processing part in 2nd Embodiment. (A) to (f) are diagrams showing the main color range extracted by the main color range extraction unit and the main color range extracted by the main color range extraction unit. (A) to (d) are diagrams showing another example in which noise is likely to be added when an image is read by using an image reading device of an image forming apparatus. (A) to (d) are diagrams showing a method of determining the validity of whether or not the validity determination unit associates each of the main color ranges. In the second embodiment, it is the flowchart explaining the procedure at the time of performing the color adjustment for outputting the image which matched the color of the image forming apparatus with an image forming apparatus. It is a block diagram explaining the functional structure of the color processing part in 3rd Embodiment. (A) to (b) are diagrams showing how the main color range extraction unit extracts the main color range from the color data. In the third embodiment, it is the flowchart explaining the procedure at the time of performing the color adjustment for outputting the image which matched the color of the image forming apparatus with an image forming apparatus.

<Explanation of the overall configuration of the image formation system>
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing an example of the overall configuration of the image forming system according to the present embodiment.
The illustrated image forming system S includes an image forming apparatus 1 and an image forming apparatus 2.
The image forming apparatus 1 and the image forming apparatus 2 are printing mechanism units that form an image on paper (recording material) based on image data, which will be described in detail later, and use at least one kind of color material to form an image on paper. To form. This image data is, for example, about an image of a print job sent from a user.
In the present embodiment, the image forming apparatus 1 and the image forming apparatus 2 are, for example, an electrophotographic type. After printing on the paper, the image forming apparatus 1 and the image forming apparatus 2 output the paper as printed matter to the outside of the apparatus. In FIG. 1, when the image forming apparatus 1 forms an image G1 (first image) on the paper P1 and outputs it, and the image forming apparatus 2 forms an image G2 (second image) on the paper P2 and outputs it. Is shown.
Further, as will be described in detail later, at least the image forming apparatus 2 is provided with an image reading apparatus 100 for reading an image, and the image reading apparatus 100 reads the image G1 formed on the paper P1.

<Overall explanation of image forming apparatus>
Next, the entire image forming apparatus 1 and the image forming apparatus 2 will be described. However, the configurations of the image forming apparatus 1 and the image forming apparatus 2 are basically the same. Therefore, the image forming apparatus 2 will be described below as an example.
FIG. 2 is an external view of the image forming apparatus 2 according to the present embodiment. FIG. 3 is a diagram showing an internal structure of the image forming apparatus 2 according to the present embodiment.
The image forming apparatus 2 includes an image reading apparatus 100 that reads an image of a document, and an image recording apparatus 200 as an example of an image forming means that forms an image on paper based on image data. The image recording device 200 functions as a first image forming means in the image forming device 1, and functions as a second image forming means in the image forming device 2. Further, the image forming apparatus 2 includes a user interface (UI) 300 for receiving operation input from the user and displaying various information to the user, and a control device 900 for controlling the operation of the entire image forming apparatus 2.

The image reading device 100 is an example of the image reading means, and is arranged above the image forming device 2. Further, the image recording device 200 is arranged below the image reading device 100 and has a built-in control device 900. The user interface 300 is arranged on the front side of the upper part of the image forming device 1, that is, on the front side of the image reading unit 110 described later of the image reading device 100.

First, the image reading device 100 will be described.
The image reading device 100 includes an image reading unit 110 that reads an image of a document, and a document conveying unit 120 that conveys the document to the image reading unit 110. The document transport unit 120 is arranged above the image reading device 100, and the image reading unit 110 is arranged below the image reading device 100.
The document transporting unit 120 has a document accommodating unit 121 for accommodating documents and a document discharging unit 122 for ejecting documents transported from the document accommodating unit 121, and the document is transmitted from the document accommodating unit 121 to the document discharging unit 122. To carry.

The image reading unit 110 includes a platen glass 111, a light irradiation unit 112 that irradiates the surface to be read (image surface) of the document with light, and the light irradiation unit 112 that irradiates the surface to be read of the document with light L. It includes a light guide unit 113 that guides the light L reflected by the surface to be read, and an imaging lens 114 that forms an optical image of the light L guided by the light guide unit 113. Further, the image reading unit 110 is composed of a photoelectric conversion element such as a CCD (Charge Coupled Device) image sensor that photoelectrically converts the light L imaged by the imaging lens 114, and detects an imaged optical image. A unit 115 and an image processing unit 116 that is electrically connected to the detection unit 115 and transmits an electric signal obtained by the detection unit 115 are provided.
The image reading unit 110 reads an image of the original document conveyed by the document conveying unit 120 and an image of the original document placed on the platen glass 111.

Next, the image recording device 200 will be described.
The image recording device 200 includes an image forming unit 20 that forms an image on the paper, a paper supply unit 60 that supplies the paper P to the image forming unit 20, and a paper P on which an image is formed by the image forming unit 20. A paper ejection unit 70 for ejecting an image, and an inverted conveying unit 80 for inverting the front and back of the paper P on which an image is formed on one side of the image forming unit 20 and conveying the paper P toward the image forming unit 20 again. ing.

The image forming unit 20 has four image forming units 21 (21Y, 21M, 21C) of yellow (Y), magenta (M), cyan (C), and black (K) arranged in parallel at regular intervals. , 21K). Each image forming unit 21 defines in advance an electrostatic latent image formed by laser irradiation by a photoconductor drum 22, a charger 23 that uniformly charges the surface of the photoconductor drum 22, and an optical system unit 50 described later. It is provided with a developer 24 that develops and visualizes with the obtained color component toner. Further, the image forming unit 20 is provided with toner cartridges 29Y, 29M, 29C and 29K for supplying toner of each color to the developing units 24 of the image forming units 21Y, 21M, 21C and 21K.

The image forming unit 20 includes an optical system unit 50 that irradiates the photoconductor drum 22 of the image forming units 21Y, 21M, 21C, 21K with a laser beam below the image forming units 21Y, 21M, 21C, 21K. There is. The optical system unit 50 includes a semiconductor laser (not shown), a modulator, a polygon mirror (not shown) that deflects and scans the laser beam emitted from the semiconductor laser, and a glass window (not shown) that passes the laser beam. , A frame (not shown) for sealing each component is provided.

Further, the image forming unit 20 includes an intermediate transfer unit 30 for multiplex transfer of toner images of each color formed on the photoconductor drums 22 of the image forming units 21Y, 21M, 21C, and 21K onto the intermediate transfer belt 31, and an intermediate transfer unit. It is provided with a secondary transfer unit 40 that transfers the toner image formed on the sheet P onto the paper P, and a fixing device 45 that heats and pressurizes the toner image formed on the paper P to fix the toner image. ..

The intermediate transfer unit 30 includes an intermediate transfer belt 31, a drive roller 32 for driving the intermediate transfer belt 31, and a tension roller 33 for applying a constant tension to the intermediate transfer belt 31. Further, the intermediate transfer unit 30 is a plurality of intermediate transfer units 30 for transferring the toner image formed on the photoconductor drum 22 facing each other with the intermediate transfer belt 31 interposed therebetween (this implementation). In this form, the primary transfer roller 34) and the backup roller 35 facing the secondary transfer roller 41 described later via the intermediate transfer belt 31 are provided.

The intermediate transfer belt 31 is attached to a plurality of rotating members such as a drive roller 32, a tension roller 33, a plurality of primary transfer rollers 34, a backup roller 35, and a driven roller 36. Then, the intermediate transfer belt 31 is circulated and driven at a predetermined speed in the arrow direction by a drive roller 32 that is rotationally driven by a drive motor (not shown). As the intermediate transfer belt 31, for example, one molded from rubber or resin is used.
Further, the intermediate transfer unit 30 is provided with a cleaning device 37 for removing residual toner and the like existing on the intermediate transfer belt 31. The cleaning device 37 removes residual toner, paper dust, and the like from the surface of the intermediate transfer belt 31 after the toner image transfer step is completed.

The secondary transfer unit 40 includes a secondary transfer roller 41 that is provided at the secondary transfer position and presses the backup roller 35 via the intermediate transfer belt 31 to secondarily transfer the image onto the paper P. The secondary transfer position where the toner image transferred to the intermediate transfer belt 31 is transferred to the paper P by the secondary transfer roller 41 and the backup roller 35 facing the secondary transfer roller 41 via the intermediate transfer belt 31. It is composed.
The fixing device 45 fixes the image (toner image) on the paper P secondarily transferred by the intermediate transfer unit 30 to the paper P by the heat fixing roller 46 and the pressure roller 47 using heat and pressure.

The paper supply unit 60 includes a paper storage unit 61 that stores paper on which an image is recorded, a delivery roll 62 that feeds out the paper P stored in each of the paper storage units 61, and a paper P that is fed out by the delivery roll 62. It is provided with a transport path 63 for transporting the paper P, and transport rolls 64, 65, 66 for transporting the paper P arranged along the transport path 63 and fed by the delivery roll 62 to the secondary transfer position.

The paper ejection unit 70 is provided above the image forming unit 20, and is provided with a first loading tray 71 for loading the paper on which the image is formed by the image forming unit 20, and the first loading tray 71 and image reading. A second loading tray 72 for loading the paper on which the image is formed by the image forming unit 20 is provided between the device 100 and the device 100.
The paper ejection unit 70 is provided on the downstream side in the transport direction from the fixing device 45, and is provided on the transport roll 75 for transporting the paper P on which the toner image is fixed and on the downstream side in the transport direction of the transport roll 75. It is provided with a switching gate 76 for switching the conveying direction of the paper P. Further, the paper ejection unit 70 transfers the paper P to be conveyed to the first loading tray 71 on the downstream side of the switching gate 76 in the conveying direction and to one side of the conveying direction (right side in FIG. 3) switched by the switching gate 76. A first discharge roll 77 for discharging is provided. Further, the paper ejection unit 70 includes a transport roll 78 for transporting the paper P transported to the downstream side of the switching gate 76 in the transport direction to the other side (upper side in FIG. 3) of the transport direction switched by the switching gate 76. It includes a second discharge roll 79 that discharges the paper P conveyed by the transfer roll 78 to the second loading tray 72.

The reversing transport unit 80 transports the inverted paper P to the side of the fixing device 45 by rotating the transport roll 78 in the direction opposite to the direction in which the paper P is discharged to the second loading tray 72. The reverse transport path 81 is provided. A plurality of transport rolls 82 are provided in the reverse transport path 81 along the reverse transport path 81. The paper P conveyed by these transfer rolls 82 is again fed to the secondary transfer position by the transfer roll 82.

Further, the image recording device 200 includes a device main frame 11 that directly or indirectly supports the image forming section 20, the paper supply section 60, the paper ejection section 70, the reverse transfer section 80, and the control device 900, and the device main body. It includes a device housing 12 that is attached to the frame 11 to form the outer surface of the image forming device 1.
The apparatus main body frame 11 is provided with a switching gate 76, a first discharge roll 77, a transfer roll 78, a second discharge roll 79, and the like on the one end side in the lateral direction of the image forming apparatus 1, and is vertically and vertically provided. It includes a reader support unit 13 that extends in the direction and supports the image reader 100. The reading device support portion 13 supports the image reading device 100 in cooperation with a portion on the back side of the device main body frame 11.

Further, the image recording device 200 is provided as a part of the device housing 12 on the front side of the image forming unit 20, and also includes a front cover 15 that is openably and closably attached to the device main body frame 11.
By opening the front cover 15, the user can replace the intermediate transfer unit 30 and the toner cartridges 29Y, 29M, 29C, and 29K of the image forming unit 20 with new ones.

The user interface 300 is, for example, a touch panel. By using the user interface 300 as a touch panel, various information such as image forming conditions of the image forming apparatus 1 is displayed on the touch panel. The user also touches the touch panel to perform input operations such as image formation conditions.

<Example of functional configuration of control device>
FIG. 4 is a block diagram showing a signal processing system in the control device 900. Here, among various functions of the control device 900, those related to signal processing are selected and shown.
The control device 900 has a data acquisition unit 91 that acquires image data created for outputting an image by the image recording device 200, and a PDL generation that receives the image data and converts it into a page description language (PDL). A unit 92, a rasterize unit 93 that creates a raster image from the PDL generated by the PDL generation unit 92, a color conversion processing unit 94 that converts RGB data into CMYK data, and a color that adjusts the color of CMYK data. The adjustment unit 95, the color processing unit 96 that creates a profile for color adjustment by the color adjustment unit 95, the raster image adjustment unit 97 that adjusts the raster image converted by the color adjustment unit 95, and halftone processing. It is provided with a halftone processing unit 98 for performing the above, and an image data output unit 99 for outputting the color-converted image data to the image recording device 200.

In the present embodiment, the data acquisition unit 91 first receives the image data. This image data is image data that a user using a PC wants to print by the image forming apparatus 2.
Then, the image data is sent to the PDL generation unit 92, and the PDL generation unit 92 converts this into code data described in PDL and outputs it.

The rasterization unit 93 converts the code data described in the PDL output from the PDL generation unit 92 into raster data for each pixel to obtain a raster image. Then, the rasterization unit 93 outputs the converted raster data as RGB (Red, Green, Blue) video data (RGB data). At this time, the rasterization unit 93 outputs RGB data for each page.

The color conversion processing unit 94 converts the RGB data input from the rasterization unit 93 into a device-independent XYZ color value, and then reproduces the color of the image recording device 200 (color of toner as a coloring material: cyan (C)). ), Magenta (M), yellow (Y), black (K)) and output after conversion to CMYK data. This CMYK data includes C color data, M color data, Y color data, and K color data separated for each color.

The color adjustment unit 95 adjusts the color of the image formed by the image recording device 200. The color adjustment unit 95 adjusts the color of the CMYK data so as to correspond to the CMYK data and match the target color that should be originally output by the image recording device 200. In the image forming apparatus 2, the color adjusting unit 95 is also used to perform color adjustment for producing an image that matches the color of the printed matter output by the image forming apparatus 1. This matter will be described later.
Color adjustment, for _example, C _in M _{in Y} in _K a _in data is converted into _{C out M} out _Y out _K out data _{((C in, M in,} Y in, K in) → (C out, M out, Y _out , K _out )) processing. In the present embodiment, this conversion _is without converting the C _in M _{in Y in K in} data to another color space such as ^L * ^a * ^{b *} color _space, and C _in M _{in Y in K in} data This is done by using a so-called device link profile that directly converts C _out M _out Y _out K _out data in the same CMYK color space. Color adjusting unit 95 stores the device link _profile, by applying the C _in M _{in Y in K in} the data in the device link profile, perform color adjustment.
In the present embodiment, the color adjusting unit 95 functions as a color adjusting means for adjusting the color of the image formed by the image recording device 200 of the image forming device 2. The device link profile is an example of a conversion relationship, and can be created as, for example, a four-dimensional LUT (Look up Table).

The color processing unit 96 creates a device link profile used for color adjustment in the color adjustment unit 95, which will be described in detail later. The color processing unit 96 is an example of a color processing apparatus. Further, the color processing unit 96 is an example of a conversion relationship creating means for creating a conversion relationship (device link profile) used for performing color adjustment in the color adjusting unit 95.

The raster image adjustment unit 97 records better image quality by performing γ conversion, definition processing, halftone processing, etc. on the C _out M _{out You out} K _out data input from the color adjustment unit 95. Make various adjustments to obtain with the device 200.

The halftone processing unit 98 performs halftone processing on the image data by the dither mask processing using the dither mask having predetermined threshold arrays in the main scanning direction and the sub scanning direction. As a result, the image data is changed from, for example, a multi-valued one to a binary-valued one.

The image data output unit 99 outputs image data that has undergone image processing such as color conversion processing to the image recording device 200.

<Explanation of color processing unit>
Next, the color processing unit 96 of the image forming apparatus 2 will be described in detail. Here, a case where the color processing unit 96 adjusts the color to match the color of the printed matter output by the image forming apparatus 1 will be described.
The color processing unit 96 creates a device link profile used for performing color adjustment as described above. Here, the color processing unit 96 will be described separately for the first to third embodiments.

[First Embodiment]
FIG. 5 is a block diagram illustrating the functional configuration of the color processing unit 96 in the first embodiment.
The color processing unit 96 includes an image data acquisition unit 961, a color conversion unit 962, a main color range extraction unit 963, an L ^* C ^* H ^* image area group extraction unit 964, and a CMYK image area group extraction unit 965. Color data acquisition unit 966, color conversion unit 967, main color range extraction unit 968, L ^* C ^* H ^* image area group extraction unit 969, L ^* a ^* b ^* image area group extraction unit 970, and the first It includes a correspondence relationship creation unit 971, a second correspondence relationship acquisition unit 972, a second correspondence relationship storage unit 973, and a conversion relationship creation unit 974.

The image data acquisition unit 961 acquires image data from the color conversion processing unit 94. That is, this image data is CMYK data as well as raster data.

The color conversion unit 962 color-converts CMYK data, which is the image data acquired by the image data acquisition unit 961. Here, CMYK data is converted into color values in the LCH color space that expresses colors by lightness, saturation, and hue, and L ^* C ^* consists of lightness (L ^* ), saturation (C ^* ), and hue (H ^* ) ^. H ^* Data.

The main color range extraction unit 963 extracts the main color range as the color range of the main color, which is the color mainly used, for the image data, which will be described in detail later. Here, the color conversion unit 962 extracts the main color range from the L ^* C ^* H ^* data after the color conversion.

The L ^* C ^* H ^* image region group extraction unit 964 extracts an image region corresponding to the main color range extracted by the main color range extraction unit 963. That is, here, this image area is extracted in the state of L ^* C ^* H ^* data.

The CMYK image area group extraction unit 965 extracts an image area corresponding to the image area extracted by the L ^* C ^* H ^* image area group extraction unit 964 from the CMYK data. That is, the image area at the same position as the image area extracted by the L ^* C ^* H ^* image area group extraction unit 964 is extracted from the CMYK data acquired by the image data acquisition unit 961.

The color data acquisition unit 966 acquires the color data (first color data) of the image G1 (first image) output by the image recording device 200 of the image forming apparatus 1. This color data is acquired, for example, by reading the printed matter using the image reading device 100 of the image forming device 2. That is, the image reading unit 110 of the image reading device 100 reads the chromaticity of the printed matter and generates color data. As the color data, for example, L ^* a ^* b ^* data is used as device-independent data. The L ^* a ^* b ^* data is data defined in the L ^* a ^* b ^* color space, which is also called the CIELAB color space. The L ^* a ^* b ^* color space is represented by a Cartesian coordinate color space centered on the lightness L ^* and the chromaticities a ^* and b ^* that represent the tint.

The CCD provided in the image reading unit 110 usually reads an image with RGB data. However, the image reading unit 110 outputs color data of the L ^* a ^* b ^* value by converting RGB to L ^* a ^* b ^* using a multidimensional table according to the reading characteristics of the CCD after reading. Can be done. For this multidimensional table, for example, an ICC profile created according to the reading characteristics of the CCD can be used.

The color conversion unit 967 color-converts the L ^* a ^* b ^* data, which is the color data acquired by the color data acquisition unit 966. Here, the L ^* a ^* b ^* data is converted into the color value of the LCH color space to obtain the L ^* C ^* H ^* data.

The main color range extraction unit 968 extracts the main color range, which is the color range of the main color, which is the color mainly used, from the color data, which will be described in detail later. Here, the color conversion unit 967 extracts the main color range from the L ^* C ^* H ^* data after the color conversion.

The L ^* C ^* H ^* image region group extraction unit 969 extracts an image region corresponding to the main color range extracted by the main color range extraction unit 968. That is, here, this image area is extracted in the state of L ^* C ^* H ^* data.

The L ^* a ^* b ^* image region group extraction unit 970 extracts an image region corresponding to the image region extracted by the L ^* C ^* H ^* image region group extraction unit 969 with respect to the L ^* a ^* b ^* data. That is, the image area at the same position as the image area extracted by the L ^* C ^* H ^* image area group extraction unit 969 is extracted with respect to the L ^* a ^* b ^* data acquired by the color data acquisition unit 966.

L ^* C ^* H ^* image area group extraction unit 964, CMYK image area group extraction unit 965, L ^* C ^* H ^* image area group extraction unit 969, and L ^* a ^* b ^* image area group extraction unit 970 are the main components. It functions as a region group extraction unit that extracts a specific region on the image as a region group based on the color range.

The first correspondence relationship creation unit 971 creates the first correspondence relationship which is the correspondence relationship between the image data and the color data.
This first correspondence is CMYK data which is image data and L ^* a ^* b ^* data which is color data (first color data) (hereinafter, this first color data is referred to as "L ^* ₁ a ^* " ^. It is a correspondence relationship (CMYK-L ^* ₁ a ^* ₁ b ^* ₁ ) with (sometimes referred to as " ₁ b ^* ₁ data"). A detailed method for creating this first correspondence will be described later.

The second correspondence acquisition unit 972 acquires the second correspondence of the image recording device 200 corresponding to the first relationship between the image data and the image forming apparatus 2.
This second correspondence is CMYK data and L ^* a ^* b ^* data which is color data (second color data) (hereinafter, this second color data is referred to as "L ^* ₂ a ^* ₂ b ^* _2". It becomes a correspondence relationship (CMYK-L ^* ₂ a ^* ₂ b ^* ₂ ) with (sometimes referred to as "data"). The second correspondence is stored in the second correspondence storage unit 973, and the second correspondence acquisition unit 972 acquires the second correspondence from the second correspondence storage unit 973.

The second correspondence is created in advance and stored in the second correspondence storage unit 973. A conventional method can be used to create the second correspondence. For example, an image of a color patch covering the entire color gamut of the image recording device 200 of the image forming device 2 is printed. Then, this is measured with a colorimeter or the like to acquire color data. The color data acquired at this time becomes the second color data (L ^* ₂ a ^* ₂ b ^* ₂ data). Therefore, a second correspondence can be obtained by associating the image data for printing the image of the color patch with the second color data.

The conversion relationship creation unit 974 sets the image forming apparatus 2 so that the color of the image G2 (second image) becomes the color of the image G1 (first image) based on the first correspondence and the second correspondence. A conversion relationship for adjusting the color of the image recording device 200 of the above is created.

Specifically, the L ^* a ^* b ^* data (L ^* ₁ a ^* ₁ b ^* ₁ data and L ^* ₂ a ^* ₂ b ^* ₂ data) of both the first correspondence and the second correspondence are used. Compare and create a correspondence between CMYK data when the L ^* a ^* b ^* data match. That is, the first correspondence relationship represents the relationship between the CMYK data, which is the image data, and the color of the image G1 printed by the image forming apparatus 1 when the CMYK data is input. The second correspondence represents the relationship with the color of the image G2 printed by the image forming apparatus 2 when the same CMYK data is input. Even if the same CMYK data is input, the printed image G1 and the image G2 usually do not have the same color because their device characteristics are different. However, the conversion relationship represents the relationship between the CMYK data when the colors of the images printed by the image forming apparatus 1 and the image forming apparatus 2 are the same. Therefore, if the CMYK data which is the image data is converted by using the conversion relationship and the image forming apparatus 2 prints using the converted CMYK data, the same color as the image G1 printed by the image forming apparatus 1 is obtained. Image G2 will be output. That is, by using this conversion relationship, the color of the printed matter output by the image forming apparatus 2 can be adjusted according to the color of the printed matter output from the image forming apparatus 1. As described above, this conversion relationship is a four-dimensional LUT and a device link profile. This device link profile is sent to the color adjustment unit 95, and the color adjustment unit 95 uses this device link profile to perform color adjustment of the image formed by the image recording device 200.

<Explanation of how to extract the main color range>
Next, the main color range extraction unit 963 and the main color range extraction unit 968 will explain a method of extracting the main color range from the image data and the color data, respectively.
The main color is a color mainly used for image data and color data as described above. There are usually multiple of these major colors. Further, the main color range is a color range that the main color can take in the image region that takes the main color. That is, in the image region that takes the main color, the colors are not uniform even if they are similar colors, and there are variations. The main color range represents the color range in which colors are included in this image area.

6 (a) to 6 (d) are diagrams showing a method in which the main color range extraction unit 963 and the main color range extraction unit 968 extract the main color range.
Of these, FIG. 6A shows an example of an image G1 (first image) formed based on the image data. Here, the image G1 is composed of the letter "F". In this case, the part of the character "F" and the part of the background have different colors. For example, the letter "F" is green and the background is yellow.

On the other hand, FIG. 6B shows an example in which the color data (first color data) when the image G1 is read is used as an image. The image of this color data is composed of the letter "F" like the image G1.

Further, FIG. 6C shows a case where the image data is converted into a histogram for each color value of L ^* , C ^* , and H ^* for the L ^* C ^* H ^* data after the color conversion by the color conversion unit 962. ..
Similarly, in FIG. 6 (d), the color data (first color data) is converted into L ^* C ^* H ^* data by the color conversion unit 967 for each color value of L ^* , C ^* , and H ^*. The case of making a histogram is shown.
In FIGS. 6 (c) and 6 (d), the horizontal axis represents each color value of L ^* , C ^* , and H ^* , and the vertical axis represents the frequency (number of pixels). Then, in FIGS. 6 (c) and 6 (d), histograms of L ^* , C ^* , and H ^* are shown for the background portion of the character “F”.

In the present embodiment, the portion having a peak for each of L ^* , C ^* , and H ^* in FIGS. 6 (c) and 6 (d) is set as the main color range. In FIGS. 6 (c) and 6 (d), this main color range is illustrated by double-headed arrows.

In the example of FIG. 6, focusing on the background of the letter "F", the color of this part (for example, yellow) was used as the main color, but focusing on the part of the letter "F", the color of this part. (For example, green) may be the main color. Further, if other colors are used in the images G1 and G2, these colors may be used as the main colors.

And ^{L * C} * ^H * data after color conversion by the color conversion unit 962 the image data, the color-converted color data (first color data) in the color conversion unit 967 and the ^{L * C} * ^H * data, Even if they are in the same image area (in this case, the area in the background of the letter "F"), they do not always match due to the influence of the color conversion error. When this is used as a histogram, the positions of the peaks of L ^* , C ^* , and H ^* are shifted (the main color range is shifted) as shown in FIGS. 6 (c) and 6 (d). However, if these positions are close to each other, it can be seen that they are from the same image area. That is, in this case, when looking at FIGS. 6 (c) and 6 (d), the same image region (for each of L ^* , C ^* , and H ^* , for the main color range having a similar frequency (number of pixels)) In this case, it can be seen that it is from the background area of the letter "F").

That is, according to this method, it is not easily affected by the color conversion error in the color conversion unit 962 and the color conversion unit 967 described above. Further, when the image reading device 100 reads the image G1 (first image) and acquires the color data (first color data), a misalignment may occur, but even if this misalignment occurs. , Less susceptible to that.

<Explanation of how to create the first correspondence>
Next, a method in which the first correspondence creating unit 971 creates the first correspondence will be described. Here, the first correspondence is created in two stages, Step1 and Step2.

In Step 1, the first correspondence creating unit 971 associates the main color ranges of the image data and the color data, and creates the first correspondence which is the correspondence between the image data and the color data.
As described above, for each of L ^* , C ^* , and H ^* , the main color range in which the peak positions are close to each other is from the same image area (in this case, the background area of the letter "F"). Therefore, these major color ranges are associated. The first correspondence relationship creation unit 971 has the average value (CMYK data) of the pixel values of the image area extracted by the CMYK image area group extraction unit 965 and the image extracted by the L ^* a ^* b ^* image area group extraction unit 970. Corresponds with the average value (L ^* a ^* b ^* data) of the pixel values of the area. In addition, since there are usually a plurality of main colors, they are also associated in the same manner. As a result, the first correspondence of CMYK-L ^* ₁ a ^* ₁ b ^* ₁ in the same image area can be created.

As described above, in the present embodiment, the L ^* C ^* H ^* image area group extraction unit 964, the CMYK image area group extraction unit 965, the L ^* C ^* H ^* image area group extraction unit 969, and the L ^* a ^* b ^* The image data and color data in the area group extracted by the image area group extraction unit 970 are used by the first correspondence relationship creation unit 971 to create the first correspondence relationship.

However, the colors included in the image data cannot usually be said to cover the entire color gamut of the image forming apparatus 1. Therefore, at the stage of Step 1, the number of first correspondences (CMYK-L ^* ₁ a ^* ₁ b ^* ₁ ) is usually small, and it cannot be said that the number is sufficient to create an accurate conversion relation. In many cases. Therefore, in the next Step 2, a process of compensating for the shortage is performed.

7 (a) to 7 (d) are diagrams illustrating Step 2 when the first correspondence creating unit 971 creates the first correspondence.
The first correspondence relationship creation unit 971 applies the image data and the acquired color data of the image G1 (first color data) to a color gamut wider than the color gamut occupied by the color data (first color data). It is applied and matched to the first correspondence candidate prepared in advance.
FIG. 7A is a conceptual diagram showing the first correspondence candidate prepared in advance.
The first correspondence candidate shown in FIG. 7A is the first correspondence (CMYK-L ^* ₁ a ^* ₁ b ^* ₁ ) for the entire color gamut (region represented by the diamond) of the image forming apparatus _1. ) Indicates that the candidates are prepared in advance.

Further, FIG. 7B shows the first correspondence (CMYK-L ^* ₁ a ^* ₁ b ^* ₁ ) obtained in Step ₁ . In this case, the first correspondence consists of 6 pieces of data.
Then, in the present embodiment, as shown in FIG. 7 (c), the image data shown in FIG. 7 (b) and the acquired color data are obtained with respect to the first correspondence candidate shown in FIG. 7 (a). Apply (first color data) and synthesize.

However, since the data included in FIGS. 7 (a) and 7 (b) are not necessarily consistent, they are not only applied but also matched. For example, from each data included in FIG. 7 (b), data closer than a predetermined Euclidean distance is removed from FIG. 7 (a). Alternatively, a weight is set according to the Euclidean distance from each data included in FIG. 7 (b), and each data included in FIG. 7 (b) is weighted by this weight.

FIG. 7D is a diagram showing the Euclidean distance d and the weight w set.
In FIG. 7D, the horizontal axis represents the Euclidean distance d and the vertical axis represents the weight w. And the relationship is w = 1 / (1 + d).
In this case, the weight w to be set becomes smaller as the Euclidean distance d from each data included in FIG. 7B is closer. For example, when the Euclidean distance d is 0, the weight w is 0, and in this case, the data shown in FIG. 7A is the same as none. Further, the weight w to be set becomes larger as the Euclidean distance d from each data included in FIG. 7B is farther. When the Euclidean distance d is larger than the predetermined Euclidean distance d ₀ , the weight w becomes 1. When the weight w is 1, it is the same as the case where the weight w is not set.

In FIG. 7 (c), among the data included in FIG. 7 (a), the positions of the data to be removed or weighted are shown by D1 to D3.
By doing so, the first correspondence creating unit 971 makes up for the shortage of the number of first correspondences in Step 1, and the first correspondence (CMYK) covering the entire color gamut of the image forming apparatus 1. -L ^* ₁ a ^* ₁ b ^* ₁ ) is created. That is, the first correspondence creating unit 971 first sets the image data and the color data (first color data) based on the color data (first color data) of the image G1 acquired in the region group in Step1. As the correspondence relationship of, the first correspondence relationship that partially covers the color range of the image forming apparatus 1 is created. Then, in the next Step 2, image formation is performed by applying and matching the first correspondence relationship that partially covers the color gamut of the image forming apparatus 1 to the first correspondence relationship candidate prepared in advance. A first correspondence relationship that covers the entire color gamut of the device 1 is created.

Note that the first correspondence (CMYK-L ^* ₁ a ^* ₁ b ^* ₁ ) obtained in Step 1 may be that the colors included in the image data cover the entire color gamut of the image forming apparatus 1. possible. In this case, the above-mentioned Step 2 processing is not necessary. Therefore, a determination unit may be provided in the first correspondence creating unit 971 as to whether or not the processing of Step 2 is necessary, and it may be determined whether or not to perform the processing of Step 2 based on the determination result of this determination unit. As this determination method, for example, the color gamut of the image forming apparatus 1 is divided, and the frequency distribution of how much data shown in FIG. 7B is included in each divided region is calculated. Then, it is determined whether or not there is a divided area that is infrequent.

Further, it is desirable that the first correspondence candidate shown in FIG. 7A is close to the first correspondence obtained in Step 1 in FIG. 7B. If the two are significantly different, the color reproduction accuracy and continuity will decrease near the boundary between the two even if the above-mentioned matching process is performed.
Therefore, a plurality of first correspondence candidates may be prepared in advance, and one of them may be selected. That is, from the plurality of first correspondence candidates, the one closer to the first correspondence obtained in Step 1 is selected. In this case, for example, the first correspondence creation unit 971 may be provided with a setting unit for selecting and setting the first correspondence candidate.

For example, if it is known that the image G1 is output under conditions close to JapanColor2011, those with the conditions of JapanColor2011 are included in the plurality of first correspondence candidates. In addition, the standard conditions that are frequently used may be included. Alternatively, the image forming apparatus sold in the past may include those with typical conditions. Further, a plurality of first correspondence candidates may be automatically generated.

According to the method described in detail above, if there is a printed matter and image data output from the image forming apparatus 1, a printed matter matching the color of the printed matter output from the image forming apparatus 1 is output from the image forming apparatus 2. In this case, the printed matter output from the image forming apparatus 1 is read by the image reading apparatus 100 of the image forming apparatus 2, but when the image forming apparatus is provided with the image reading apparatus 100, the user can use the image reading apparatus 100 to read the original. The color adjustment is completed only by reading the image, and printing is executed by the image forming apparatus 2. Therefore, the user does not have to have specialized skills.
Further, in the present embodiment, the first correspondence relationship creation unit 971 creates the first correspondence relationship by performing Step 2 described above. As a result, even if the color used in the image G1 of the printed matter output from the image forming apparatus 1 is partial with respect to the color reproduction range of the image forming apparatus 1, the first correspondence creating unit 971 is more accurate. Create a high conversion relationship. Therefore, even in such a case, the accuracy of color adjustment is unlikely to decrease.

<Explanation of color adjustment procedure of image forming apparatus 2>
Next, in the first embodiment, a procedure for performing color adjustment for outputting the image G2 matching the color of the image forming apparatus 1 by the image forming apparatus 2 will be described.

FIG. 8 is a flowchart illustrating a procedure for performing color adjustment in the image forming apparatus 2 for outputting an image G2 matching the color of the image forming apparatus 1 in the first embodiment. Further, FIGS. 9 (a) to 9 (i) are diagrams showing the actual processing performed at this time.
Hereinafter, description will be given with reference to FIGS. 5, 8 and 9.

First, a printed matter on which the image G1 (first image) output by the image forming apparatus 1 is printed and image data when the printed matter is printed are prepared (step 101).

The image data acquisition unit 961 acquires this image data (step 102: FIG. 9A). This image data is CMYK data.
Next, the color conversion unit 962 color-converts the image data acquired by the image data acquisition unit 961 and converts the CMYK data into L ^* C ^* H ^* data (step 103: FIG. 9B).
Then, the main color range extraction unit 963 creates a histogram of the L ^* C ^* H ^* data after color conversion by the color conversion unit 962 as shown in FIG. 6 (c), and extracts the main color range (step 104). ..
Further, the L ^* C ^* H ^* image region group extraction unit 964 extracts the image region corresponding to the main color range extracted by the main color range extraction unit 963 from the L ^* C ^* H ^* data (step 105: FIG. 9). (C)). In this case, in the example of FIG. 9C, the background area of the character “F” is extracted.
Further, the CMYK image area group extraction unit 965 extracts an image area corresponding to the image area extracted by the L ^* C ^* H ^* image area group extraction unit 964 from the CMYK data (step 106: FIG. 9D). ..

Next, the image reading device 100 of the image forming device 2 reads the image G1 (first image) (step 107).
The color data (first color data) of the image G1 read by the image reading device 100 is sent to the color processing unit 96 of the control device 900, and the color data acquisition unit 966 of the control device 900 receives the color data (first color data). (1 color data) is acquired (step 108: FIG. 9 (e)). This image data is L ^* a ^* b ^* data.

Next, the color conversion unit 967 color-converts the color data acquired by the color data acquisition unit 966 to convert the L ^* a ^* b ^* data into L ^* C ^* H ^* data (step 109: FIG. 9 (f)). ..
Then, the main color range extraction unit 968 creates a histogram of the L ^* C ^* H ^* data after color conversion by the color conversion unit 967 as shown in FIG. 6 (d), and extracts the main color range (step 110). ..
Further, the L ^* C ^* H ^* image region group extraction unit 969 extracts an image region corresponding to the main color range extracted by the main color range extraction unit 968 from the L ^* C ^* H ^* data (step 111: FIG. 9). (G)). In this case, in the example of FIG. 9 (g), the background area of the character "F" is extracted.
Further, the L ^* a ^* b ^* image area group extraction unit 970 extracts the image area corresponding to the image area extracted by the L ^* C ^* H ^* image area group extraction unit 969 with respect to the L ^* a ^* b ^* data. (Step 112: FIG. 9 (h)).

Next, the first correspondence relationship creation unit 971 associates the main color ranges of the image data and the color data with each other, and is the first correspondence relationship in Step 1 described above, which is the correspondence relationship between the image data and the color data. The first correspondence is created (step 113). At this time, the first correspondence creation unit 971 uses the average value of the pixel values (average data of CMYK data) in the background area of the character "F" and the L ^* a ^* b ^* image area group extraction unit 970. Corresponds to the average value of the pixel values in the extracted image area (average data of L ^* a ^* b ^* data). In the example of FIG. 9 (i), (C, M, Y, K) = (0, 11, 50, 0), and (L ^* , a ^* , b ^* ) = (85, 1, 26). To associate.

Then, the first correspondence relation creation unit 971 fits and matches the first correspondence relation created in step 113 with respect to the first correspondence relation candidate prepared in advance. As a result, the first correspondence creating unit 971 creates the first correspondence which is the first correspondence in Step 2 described above and covers the entire color gamut of the image forming apparatus 1 (step 114).

Further, the second correspondence acquisition unit 972 acquires the second correspondence stored in the second correspondence storage unit 973 (step 115).

Then, the conversion relationship creation unit 974 creates a conversion relationship for performing color adjustment of the image recording device 200 of the image forming device 2 from the first correspondence relationship and the second correspondence relationship (step 116).
This conversion relationship is output to the color adjustment unit 95 by the conversion relationship creation unit 974 as a device link profile (step 117).

The color adjustment unit 95 converts the image data so that the color of the image G2 becomes the color of the image G1 by this device link profile. As a result, the image G2 output by the image forming apparatus 2 is matched to the color of the image G1 output by the image forming apparatus 1.

[Second Embodiment]
FIG. 10 is a block diagram illustrating the functional configuration of the color processing unit 96 in the second embodiment.
The color processing unit 96 in the second embodiment shown in FIG. 10 has the same configuration as the color processing unit 96 in the first embodiment shown in FIG. 5 except that the validity determination unit 975 is added. Have.
In the second embodiment, the functions of the processing units other than the validity determination unit 975 are substantially the same as those in the first embodiment. Therefore, the validity determination unit 975 will be mainly described below.

11 (a) to 11 (f) are views showing the main color range extracted by the main color range extraction unit 963 and the main color range extracted by the main color range extraction unit 968.
In this example, the main color range extraction unit 963 and the main color range extraction unit 968 extract two main colors and extract each main color range. That is, the color of the background region of the letter "F" is the main color, and the color of the portion of the letter "F" is the main color. Here, the former may be referred to as a "first main color" and the latter may be referred to as a "second main color". Further, the main color ranges of the first main color and the second main color may be referred to as "first main color range" and "second main color range".

Here, FIG. 11A shows a histogram created by the main color range extraction unit 963. That is, this is a histogram created by color-converting the image data by the color conversion unit 962 and using the L ^* C ^* H ^* data obtained as a result.
Further, FIG. 11B shows a histogram created by the main color range extraction unit 968. That is, this is a histogram created by color-converting the color data (first color data) by the color conversion unit 967 and using the L ^* C ^* H ^* data obtained as a result.

Then, FIG. 11 (c) shows the first main color range extracted by the main color range extraction unit 963 based on the histogram of FIG. 11 (a).
Further, FIG. 11D shows a first main color range extracted by the main color range extraction unit 968 based on the histogram of FIG. 11B.
Further, FIG. 11 (e) shows the second main color range extracted by the main color range extraction unit 963 based on the histogram of FIG. 11 (a).
Further, FIG. 11 (f) shows the second main color range extracted by the main color range extraction unit 968 based on the histogram of FIG. 11 (b).
In order to extract the first main color range and the second main color range in this way, a known method such as clustering can be used.

Comparing the first main color range of FIGS. 11 (c) and 11 (d), the background region of the character "F" has a wide image region and therefore has a high frequency (number of pixels). Therefore, a clear peak occurs for the first main color, and therefore the first main color range can be obtained with high accuracy.

On the other hand, when the second main color range of FIGS. 11 (e) and 11 (f) is compared, the color data (first) of FIG. 11 (e), which is a histogram with respect to the image data, has a clear peak. It can be seen that no clear peak has occurred in FIG. 11 (f), which is a histogram with respect to the color data of (1). Since this is to acquire the color data (first color data) of the image G1 (first image), various noises are added when the image G1 is read by using the image reading device 100 of the image forming apparatus 2. Due to the ease. In particular, the area of the letter "F" has a narrow image area, and therefore the frequency (number of pixels) is low, the height of the peak of the second main color is smaller, and it is more susceptible to noise. As a result, such a clear peak may not occur. In this case, it tends to be difficult to accurately obtain the second main color range, and the accuracy of the first correspondence tends to decrease.

Further, FIGS. 12A to 12D are views showing another example in which noise is likely to be added when the image G1 is read by using the image reading device 100 of the image forming device 2.
Of these, FIGS. 12A to 12B show a case where the image G1 is a screen-processed image.
FIG. 12A shows a histogram of the image G1 and the image data. In this case, the image G1 is a uniform gray, and the histogram of the image data underlying the image G1 shows a clear peak.
On the other hand, FIG. 12B shows a histogram of the color data and the color data (first color data) obtained by reading the image G1 by the image reading device 100 of the image forming apparatus 2 as an image. In this case, since the image G1 is screen-processed, the color data image read by the image reading device 100 has color variations. As a result, the histogram of this color data does not show a clear peak.

Further, FIGS. 12 (c) to 12 (d) show a case where blurring occurs when the image G1 is read by using the image reading device 100 of the image forming device 2.
FIG. 12C shows a histogram of the image G1 and the image data. In this case, the image G1 is a uniform gray, and the histogram of the image data underlying the image G1 shows a clear peak.
On the other hand, FIG. 12D shows a histogram of the color data and the color data (first color data) obtained by reading the image G1 by the image reading device 100 of the image forming apparatus 2 as an image. In this case, blurring occurs when the image G1 is read. As a result, the histogram of this color data does not show a clear peak.
In addition, the same applies when blurring occurs when printing the image G1 using the image recording device 200 of the image forming device 1.

Therefore, in the second embodiment, the validity determination unit 975 is provided to suppress this problem.
The validity determination unit 975 compares the main color range extracted by the main color range extraction unit 963 with the main color range extracted by the main color range extraction unit 968, and determines the validity of the association. At this time, the validity determination unit 975 determines the validity of whether or not to associate each of the main color ranges from the similarity of the characteristics of the pixels included in the extracted main color range for each of the image data and the acquired color data. Judge and determine the main color range used to create the first correspondence.

13 (a) to 13 (d) are diagrams showing a method of determining the validity of whether or not the validity determination unit 975 associates each of the main color ranges.
Of these, FIG. 13A shows the frequency (number of pixels) and the first main color range for the first main color extracted by the main color range extraction unit 963 based on the image data. Further, FIG. 13B shows the frequency (number of pixels) and the first main color range of the first main color extracted by the main color range extraction unit 968 based on the color data. That is, in FIGS. 13 (a) and 13 (b), the frequency (number of pixels) and the range of possible colors are shown in the background region of the character “F”.

Then, in order to determine the similarity of the characteristics of the pixels constituting the first main color, the similarity of the frequency (the number of pixels) is used as a reference. In this case, in FIG. 13A, the frequency (number of pixels) of entering the first main color range is 652. Further, in FIG. 13B, the frequency (number of pixels) of entering the first main color range is 667. Then, if the difference in frequency (number of pixels) is within the range of a predetermined threshold value, it is determined that the similarity is high, and if it exceeds the threshold value, it is determined that the similarity is low.

Further, FIG. 13C shows the frequency (number of pixels) and the second main color range of the second main color extracted by the main color range extraction unit 963 based on the image data. Further, FIG. 13D shows the frequency (number of pixels) and the second main color range of the second main color extracted by the main color range extraction unit 968 based on the color data. That is, in FIGS. 13 (c) and 13 (d), the frequency (number of pixels) and the range of possible colors are shown in the area of the character "F".

Then, in order to determine the similarity of the characteristics of the pixels constituting the second main color, the similarity of the frequency (number of pixels) is used as a reference as in the case of the first main color. In this case, in FIG. 13C, the frequency (number of pixels) of entering the first main color range is 132. Further, in FIG. 13D, the frequency (number of pixels) of entering the first main color range is 117. Then, if the difference in frequency (number of pixels) is within the range of a predetermined threshold value, it is determined that the similarity is high, and if it exceeds the threshold value, it is determined that the similarity is low.

In the above-mentioned example, the similarity of the characteristics of the pixels constituting the main color is determined based on the similarity of the frequency (number of pixels), but the present invention is not limited to this. For example, the similarity of pixel values (color values) may be used as a reference. In this case, for example, image data or color data (first color data) is binarized, and the difference in frequency (number of pixels) of pixel values of "0" or "1" is within a predetermined threshold range. It is judged that the similarity is high, and if the threshold is exceeded, the similarity is judged to be low. Further, the similarity of the main color range may be used as a reference.

In the second embodiment, the validity determination unit 975 compares the main color range extracted by the main color range extraction unit 963 with the main color range extracted by the main color range extraction unit 968, and determines the validity of the association. to decide. And where appropriate, this primary color range is used to create the first correspondence. If not valid, this primary color range is used to create the first correspondence. As a result, the first correspondence can be obtained more accurately, and a more accurate conversion relationship can be created.

Next, in the second embodiment, a procedure for performing color adjustment for outputting the image G2 matching the color of the image forming apparatus 1 by the image forming apparatus 2 will be described.

FIG. 14 is a flowchart illustrating a procedure for performing color adjustment in the image forming apparatus 2 for outputting the image G2 matching the color of the image forming apparatus 1 in the second embodiment.
In FIG. 14, steps 201 to 210 are the same as steps 101 to 110 in FIG.
After that, the validity determination unit 975 compares the main color range extracted by the main color range extraction unit 963 with the main color range extracted by the main color range extraction unit 968, and determines the validity of the association (step 211). ). Thus, the validation unit 975 determines the primary color used to create the first correspondence.

After that, steps 212 to 218 are the same as steps 111 to 117 in FIG. At this time, in step 214, the first correspondence creating unit 971 creates the first correspondence in Step 1 described above using the main color range of the main colors determined in step 211.

[Third Embodiment]
FIG. 15 is a block diagram illustrating the functional configuration of the color processing unit 96 in the third embodiment.
The color processing unit 96 in the third embodiment shown in FIG. 15 has the same configuration as the color processing unit 96 in the first embodiment shown in FIG. 5 except that the frequency calculation unit 976 is added. ..
In the third embodiment, the functions of each processing unit other than the frequency calculation unit 976 are substantially the same as those in the first embodiment. Therefore, the frequency calculation unit 976 will be mainly described below.

The frequency calculation unit 976 calculates the frequency (number of pixels) in the main color range extracted from the image data by the main color range extraction unit 963. Then, when the main color range extraction unit 968 extracts the main color range from the color data, the main color range of the peak having a frequency (number of pixels) close to the frequency (number of pixels) calculated by the frequency calculation unit 976 is mainly used for the color data. The color range. That is, the main color range extraction unit 968 determines the main color range of the color data based on the number of pixels included in the main color range of the image data.

16 (a) to 16 (b) are views showing how the main color range extraction unit 968 extracts the main color range from the color data.
FIG. 16A shows a histogram created by the main color range extraction unit 963. Then, the main color range extraction unit 963 extracts the range indicated by the double-headed arrow in FIG. 16A as the main color range. In this case, it is shown that the range shown in the lower table of FIG. 16A was extracted as the main color range.
Then, the frequency calculation unit 976 calculates the frequency (number of pixels) in the main color range. In this case, the frequency (number of pixels) is 652.
Then, the main color range extraction unit 968 sets the peak color range having a frequency (number of pixels) close to the frequency (number of pixels) 652 calculated by the frequency calculation unit 976 as the main color range for the color data. In FIG. 16B, the main color range extracted by this is indicated by double-headed arrows.

According to the third embodiment, it becomes easier to associate the main color range extracted for the image data by the main color range extraction unit 963 with the main color range extracted for the color data by the main color range extraction unit 968. ..

Next, in the third embodiment, a procedure for performing color adjustment for outputting the image G2 matching the color of the image forming apparatus 1 by the image forming apparatus 2 will be described.

FIG. 17 is a flowchart illustrating a procedure for performing color adjustment in the image forming apparatus 2 for outputting the image G2 matching the color of the image forming apparatus 1 in the third embodiment.
In FIG. 17, steps 301 to 304 are the same as steps 101 to 104 in FIG.
After that, the frequency calculation unit 976 calculates the frequency (number of pixels) in the main color range extracted from the image data by the main color range extraction unit 963 (step 305).

After that, steps 306 to 310 are the same as steps 105 to 109 in FIG.
Then, the main color range extraction unit 968 extracts the peak color range having a frequency (number of pixels) close to the frequency (number of pixels) 652 calculated by the frequency calculation unit 976 as the main color range for the color data (step 311).
After that, steps 312 to 318 are the same as steps 111 to 117 in FIG.

In the example described in detail above, the image reading device 100 is built in the image forming device 2, but each may be a separate body and the image reading device 100 may be an independent device.
Similarly, although the control device 900 is built in the image forming device 2, the functions performed by the color processing unit 96 of the control device 900 are made independent and executed by, for example, a PC (Personal Computer), a tablet terminal, a smartphone, or the like. You may. In this case, the function of the color processing unit 96 can be realized by software (program) operating in these devices.

Although the present embodiment has been described above, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is clear from the description of the scope of claims that the above-described embodiment with various modifications or improvements is also included in the technical scope of the present invention.

1, 2 ... Image forming device, 96 ... Color processing unit, 100 ... Image reading device, 200 ... Image recording device, 900 ... Control device, 961 ... Image data acquisition unit, 962, 967 ... Color conversion unit, 963, 968 ... Main color range extraction unit, 964, 969 ... L ^* C ^* H ^* Image area group extraction unit, 965 ... CMYK image area group extraction unit, 966 ... Color data acquisition unit, 970 ... L ^* a ^* b ^* Image area group extraction Unit, 971 ... 1st correspondence relationship creation unit, 972 ... 2nd correspondence relationship acquisition unit, 973 ... second correspondence relationship storage unit, 974 ... conversion relationship creation unit, S ... image formation system

Claims (8)

A color data acquisition unit that acquires color data of the first image output by the first image forming means based on the image data, and a color data acquisition unit.
For each of the image data and the acquired color data, a main color range extraction unit that extracts a main color range as a color range of a main color that is mainly used, and a main color range extraction unit.
A region group extraction unit that extracts a specific region on the image as a region group based on the main color range,
A first correspondence relationship creation unit that associates the main color ranges of the image data and the color data and creates a first correspondence relationship that is a correspondence relationship between the image data and the color data.
Equipped with a,
A color processing apparatus characterized in that the image data and the color data in the region group are used by the first correspondence creating unit to create the first correspondence . The main color range extraction unit is used to create the first correspondence from the similarity of the characteristics of the pixels included in the extracted main color range for each of the image data and the acquired color data. The color processing apparatus according to claim 1, wherein the main color range is determined. The color processing according to claim 1 or 2, wherein the main color range extraction unit determines the main color range of the color data based on the number of pixels of the pixels included in the main color range of the image data. apparatus. From the first correspondence and the second correspondence of the second image forming means corresponding to the first correspondence, the second image forming means outputs based on the image data. Claim 1 further includes a conversion relationship creating unit that creates a conversion relationship that adjusts the color of the second image forming means so that the color of the image 2 becomes the color of the first image. The color processing apparatus according to any one of items 3 to 3 . The first correspondence relationship is created by fitting and matching the image data and the acquired color data of the first image to the first correspondence relationship candidate prepared in advance. The color processing apparatus according to any one of claims 1 to 4 , which is characterized. A color data acquisition unit that acquires color data of the first image output by the first image forming means based on the image data, and a color data acquisition unit.
For each of the image data and the acquired color data, a main color range extraction unit that extracts a main color range as a color range of a main color, which is a color mainly used,
A first correspondence relationship creation unit that associates the main color ranges of the image data and the color data and creates a first correspondence relationship that is a correspondence relationship between the image data and the color data.
Equipped with a,
The main color range extraction unit is used to create the first correspondence from the similarity of the number of pixels included in the main color range extracted for each of the image data and the acquired color data. A color processing device characterized in determining a range. A second image forming means for forming an image on a recording material based on the image data,
A color adjusting means for adjusting the color of an image formed by the second image forming means, and
A conversion relationship creating means for creating a conversion relationship used for performing color adjustment with the color adjusting means,
With
The conversion relationship creating means
A color data acquisition unit that acquires color data of the first image output by the first image forming means based on the image data, and a color data acquisition unit.
For each of the image data and the acquired color data, a main color range extraction unit that extracts a main color range as a color range of a main color, which is a color mainly used,
A region group extraction unit that extracts a specific region on the image as a region group based on the main color range,
A first correspondence relationship creation unit that associates the main color ranges of the image data and the color data and creates a first correspondence relationship that is a correspondence relationship between the image data and the color data.
From the first correspondence relationship and the second correspondence relationship of the second image forming means corresponding to the first correspondence relationship, the second image forming means outputs based on the image data. A conversion relationship creating unit that creates a conversion relationship that adjusts the color of the second image forming means so that the color of the second image becomes the color of the first image.
Equipped with a,
An image forming apparatus, characterized in that the image data and the color data in the region group are used by the first correspondence creating unit to create the first correspondence . A first image forming means for forming an image on a recording material based on image data,
A second image forming means for forming an image on a recording material based on the image data,
A color adjusting means for adjusting the color of an image formed by the second image forming means, and
A conversion relationship creating means for creating a conversion relationship used for performing color adjustment with the color adjusting means,
With
The conversion relationship creating means
A color data acquisition unit that acquires color data of a first image output by the first image forming means based on the image data, and a color data acquisition unit.
For each of the image data and the acquired color data, a main color range extraction unit that extracts a main color range as a color range of a main color that is mainly used, and a main color range extraction unit.
A region group extraction unit that extracts a specific region on the image as a region group based on the main color range,
A first correspondence relationship creation unit that associates the main color ranges of the image data and the color data and creates a first correspondence relationship that is a correspondence relationship between the image data and the color data.
From the first correspondence relationship and the second correspondence relationship of the second image forming means corresponding to the first correspondence relationship, the second image forming means outputs based on the image data. A conversion relationship creating unit that creates a conversion relationship that adjusts the color of the second image forming means so that the color of the second image becomes the color of the first image.
Equipped with a,
An image forming system characterized in that the image data and the color data in the region group are used by the first correspondence creating unit to create the first correspondence .