JP2018085622A - Color processing apparatus, image forming apparatus, and image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color processing apparatus that, in establishing a conversion relationship for adjusting the color of a printed matter output from image forming means to a desired color, can establish more accurate conversion relationship even with the presence of an error and misregistration due to color conversion.SOLUTION: A color processing apparatus comprises: a color data acquisition part 966 that acquires color data of a first image output from first image forming means on the basis of image data; principal color range extraction parts 963 and 968 that, for the image data and respective color data, extract a principal color range as a color range of a principal color that is a color principally used; and a first correspondence relationship establishment part 971 that associates the principal color ranges of the image data and respective color data to establish a first correspondence relationship that is a correspondence relationship between the image data and color data.SELECTED DRAWING: Figure 5

Description

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

In the recent printing market, the shift from offset printing machines to on-demand digital printing machines has been gradually accelerating. One of the use cases of on-demand printers is reprinting. There are cases where a large number of copies are printed by an offset printing machine and then printed by a small number of copies by an on-demand printer, or cases where only an on-demand printer is used without using an offset printing machine.
In order to match the color of the printed matter output in the past and the printed matter at the time of extra printing at the time of such reprinting, color conversion profiles can be created by measuring color patches printed in the past, or past print output conditions ( It is necessary to output under the same conditions as the color conversion profile setting.

  Japanese Patent Application Laid-Open No. 2004-151867 discloses alignment means for performing alignment between first output image data and document image data, alignment between second output image data and document image data, and first color component value association data. And color component value associating means for generating second color component value associating data, color tone conversion parameter determining means for generating a tone conversion parameter for converting the tone, and original image data by the tone conversion parameter An image processing apparatus having a color tone converting means for converting the pixel value of the image is disclosed.

JP2013-30996A

  The present invention creates a conversion relationship with higher accuracy even when 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. For the purpose.

According to the first aspect of the present invention, a color data acquisition unit that acquires color data of the first image output by the first image forming unit based on the image data, 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 a color that is mainly used, and the main color range of the image data and the color data are associated with each other, and the image data And a first correspondence relationship creating unit that creates a first correspondence relationship between the color data and the color data.
According to the second aspect of the present invention, the primary color range extraction unit is configured to calculate the first color from the similarity of characteristics of pixels included in the primary 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 to create the correspondence relationship 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 3. The color processing apparatus according to Item 1 or 2.
The invention according to claim 4 further includes a region group extraction unit that extracts a specific region on the image as a region group based on the main color range, and the image data and the color data in the region group are 4. The color processing apparatus according to claim 1, wherein the color processing apparatus is used to create the first correspondence relationship by a first correspondence relationship creation unit. 5.
According to a fifth aspect of the present invention, the second correspondence relationship based on the image data is obtained from the first correspondence relationship and the second correspondence relationship for the second image forming unit corresponding to the first correspondence relationship. A conversion relationship creating unit that creates a conversion relationship for performing color adjustment of the second image forming means so that the color of the second image output by the image forming means becomes the color of the first image. The color processing apparatus according to claim 1, further comprising: a color processing apparatus according to claim 1;
According to a sixth aspect of the present invention, the first correspondence relationship is obtained by applying the image data and the acquired color data of the first image to a first correspondence relationship candidate prepared in advance. 6. The color processing apparatus according to claim 1, wherein the color processing apparatus is created by matching.
According to a seventh aspect of the present invention, there is provided a second image forming unit that forms an image on a recording material based on image data, and a color adjusting unit that performs color adjustment of an image formed by the second image forming unit. Conversion relation creating means for creating a conversion relation used for color adjustment by the color adjusting means, and the conversion relation creating means is output by the first image forming means based on the image data A color data acquisition unit that acquires color data of the first image that has been obtained, and extracts a main color range as a color range of a main color that is mainly used for each of the image data and the acquired color data A primary color range extraction unit that associates the primary color ranges of the image data and the color data, and creates a first correspondence that is a correspondence between the image data and the color data Relationship creation department Based on the image data, the second image forming means outputs the first correspondence relation and the second correspondence relation for the second image forming means corresponding to the first correspondence relation. A conversion relationship creating unit that creates a conversion relationship for performing color adjustment of the second image forming unit so that the color of the second image becomes the color of the first image. Forming device.
The invention according to claim 8 is 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 unit that performs color adjustment of an image formed by the second image forming unit, and a conversion relationship creating unit that creates a conversion relationship used for performing color adjustment by the color adjusting unit, The conversion relationship creating means includes a color data obtaining unit for obtaining color data of the first image output by the first image forming means based on the image data, and the image data and the obtained color data. A main color range extraction unit that extracts a main color range as a color range of a main color that is a color that is mainly used, and the main color range of the image data and the color data are associated with each other, and the image data And the color A first correspondence relation creating unit that creates a first correspondence relation that is a correspondence relation with the first correspondence relation, the first correspondence relation, and the second image forming unit corresponding to the first correspondence relation. Based on the second correspondence relationship, the second image forming means so that 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. And a conversion relationship creating unit that creates a conversion relationship for performing color adjustment of the image.

According to the first aspect of the present invention, in creating the conversion relationship for matching the color of the printed matter output from the image forming means to the desired color, even if there is an error or misalignment due to color conversion, the accuracy is higher. It is possible to provide a color processing apparatus that makes it possible to create a conversion relationship.
According to the invention of claim 2, the first correspondence relationship can be obtained with higher accuracy, 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, it becomes easier to grasp the difference in color between the first image and the second image.
According to the invention of claim 5, the second image forming means matches the color of the printed matter output from the first image forming means on the basis of the printed matter and image data output from the first image forming means. Printouts can be output.
According to the invention of claim 6, the accuracy of the first correspondence relationship is further improved.
According to the seventh aspect of the present invention, in creating a conversion relationship for matching the color of the printed matter output from the image forming unit to a desired color, even if there is an error or misalignment due to color conversion, the accuracy is higher. An image forming apparatus that makes it possible to create a conversion relationship can be provided.
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.

1 is a diagram illustrating an example of an overall configuration of an image forming system according to an exemplary embodiment. 1 is an external view of an image forming apparatus according to the present embodiment. 1 is a diagram illustrating an internal structure of an image forming apparatus according to an embodiment. It is a block diagram which shows the signal processing system in a control apparatus. It is a block diagram explaining the functional structure of the color processing part in 1st Embodiment. (A)-(d) is the figure shown about the method in which a main color range extraction part and a main color range extraction part extract a main color range. (A)-(d) is a figure explaining Step2 when the 1st correspondence creation part creates the 1st correspondence. 6 is a flowchart illustrating a procedure when performing color adjustment for outputting an image in accordance with the color of the image forming apparatus in the image forming apparatus in the first embodiment. (A)-(i) is the figure shown about the actual process at the time of performing the color adjustment for outputting the image match | combined with the color of the image forming apparatus with the image forming apparatus. It is the block diagram explaining the functional structure of the color processing part in 2nd Embodiment. (A)-(f) is the figure shown about the main color range which the main color range extraction part extracted, and the main color range which the main color range extraction part extracted. (A)-(d) is the figure shown about the other example in which a noise is easy to add when reading an image using the image reader of an image forming apparatus. (A)-(d) is the figure shown about the method of judging the validity whether a validity judgment part matches each main color range. 10 is a flowchart illustrating a procedure for performing color adjustment for outputting an image in accordance with the color of the image forming apparatus in the image forming apparatus in the second embodiment. It is the block diagram explaining the functional structure of the color processing part in 3rd Embodiment. (A)-(b) is the figure which showed a mode that the main color range extraction part extracts the main color range about color data. 10 is a flowchart illustrating a procedure when performing color adjustment for outputting an image in accordance with the color of the image forming apparatus in the image forming apparatus in the third embodiment.

<Description of overall configuration of image forming system>
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating an example of the overall configuration of an 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 a sheet (recording material) based on image data, and will be described in detail later. Form. This image data is, for example, an image of a print job transmitted from the user.
In the present embodiment, the image forming apparatus 1 and the image forming apparatus 2 are, for example, of an electrophotographic system. After printing on the paper, the image forming apparatus 1 and the image forming apparatus 2 output the paper as a printed matter outside the apparatus. In FIG. 1, the image forming apparatus 1 forms and outputs an image G1 (first image) on a sheet P1, and the image forming apparatus 2 forms and outputs an image G2 (second image) on a sheet P2. Is shown.
As will be described in detail later, at least the image forming apparatus 2 includes an image reading apparatus 100 that reads an image, and the image reading apparatus 100 reads an image G1 formed on the paper P1.

<Overall Description 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 the internal structure of the image forming apparatus 2 according to this 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 that is an example of an image forming unit that forms an image on a sheet based on image data. The image recording apparatus 200 functions as a first image forming unit in the image forming apparatus 1 and functions as a second image forming unit in the image forming apparatus 2. In addition, the image forming apparatus 2 includes a user interface (UI) 300 that receives an operation input from a user and displays various information for the user, and a control device 900 that controls the operation of the entire image forming apparatus 2.

  The image reading apparatus 100 is an example of an image reading unit, and is disposed on the upper part of the image forming apparatus 2. The image recording apparatus 200 is disposed below the image reading apparatus 100 and includes a control device 900. The user interface 300 is arranged on the front side on the upper side of the image forming apparatus 1, that is, on the front side of an image reading unit 110 described later of the image reading apparatus 100.

First, the image reading apparatus 100 will be described.
The image reading apparatus 100 includes an image reading unit 110 that reads an image of a document, and a document transport unit 120 that transports the document to the image reading unit 110. The document conveying unit 120 is disposed at the upper part of the image reading apparatus 100, and the image reading unit 110 is disposed at the lower part of the image reading apparatus 100.
The document transport unit 120 includes a document storage unit 121 that stores a document, and a document discharge unit 122 that discharges a document transported from the document storage unit 121. Transport.

The image reading unit 110 includes a platen glass 111, a light irradiation unit 112 that irradiates light on a reading surface (image surface) of a document, and light L is irradiated from the light irradiation unit 112 to a reading surface of the document. 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 are provided. The image reading unit 110 includes 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 optical image that has been imaged. And an image processing unit 116 that is electrically connected to the detection unit 115 and to which an electrical signal obtained by the detection unit 115 is transmitted.
The image reading unit 110 reads an image of a document transported by the document transport unit 120 and an image of a document placed on the platen glass 111.

Next, the image recording apparatus 200 will be described.
The image recording apparatus 200 includes an image forming unit 20 that forms an image on a sheet, a sheet supply unit 60 that supplies the sheet P to the image forming unit 20, and a sheet P on which an image is formed by the image forming unit 20. A paper discharge unit 70 for discharging the paper, and a reverse conveyance unit 80 that reverses the front and back of the paper P on which one side of the image P is formed by the image forming unit 20 and conveys the paper P toward the image forming unit 20 again. ing.

  The image forming unit 20 includes four image forming units 21 (21Y, 21M, and 21C) of yellow (Y), magenta (M), cyan (C), and black (K) that are arranged in parallel at regular intervals. 21K). Each image forming unit 21 predetermines an electrostatic latent image formed by laser irradiation by a photosensitive drum 22, a charger 23 that uniformly charges the surface of the photosensitive drum 22, and an optical system unit 50 described later. And a developing unit 24 that develops and visualizes 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 devices 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 photosensitive drum 22 of the image forming units 21Y, 21M, 21C, and 21K with laser light below the image forming units 21Y, 21M, 21C, and 21K. Yes. The optical system unit 50 includes a semiconductor laser and a modulator (not shown), a polygon mirror (not shown) that deflects and scans laser light emitted from the semiconductor laser, and a glass window (not shown) that passes the laser light. And a frame (not shown) for sealing each component.

  The image forming unit 20 includes an intermediate transfer unit 30 that multiplex-transfers toner images of respective colors formed on the photosensitive drums 22 of the image forming units 21Y, 21M, 21C, and 21K onto the intermediate transfer belt 31, and an intermediate transfer unit. A secondary transfer unit 40 that transfers the toner image formed on the paper 30 to the paper P; and a fixing device 45 that fixes the toner image formed on the paper P by heating and pressing. .

  The intermediate transfer unit 30 includes an intermediate transfer belt 31, a drive roller 32 that drives the intermediate transfer belt 31, and a tension roller 33 that applies a constant tension to the intermediate transfer belt 31. Further, the intermediate transfer unit 30 has a plurality of (this embodiment) for transferring the toner images formed on the photosensitive drum 22 facing each photoconductor drum 22 and the intermediate transfer belt 31 on the intermediate transfer belt 31. In this embodiment, four primary transfer rollers 34 and a backup roller 35 opposed to a secondary transfer roller 41 described later via an intermediate transfer belt 31 are provided.

The intermediate transfer belt 31 is stretched around 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. The intermediate transfer belt 31 is circulated and driven at a predetermined speed in the direction of the arrow by a drive roller 32 that is rotationally driven by a drive motor (not shown). As the intermediate transfer belt 31, for example, a belt formed of rubber or resin is used.
Further, the intermediate transfer unit 30 includes a cleaning device 37 that removes 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 process 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 secondary-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 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 using heat and pressure by the heat fixing roller 46 and the pressure roller 47.

  The paper supply unit 60 includes a paper storage unit 61 that stores paper on which an image is recorded, a feed roll 62 that sends out the paper P stored in each of the paper storage units 61, and a paper P that is sent out by the feed roll 62. Are conveyed along the conveying path 63, and conveying rolls 64, 65, and 66 that convey the paper P disposed along the conveying path 63 and sent out by the delivery roll 62 to the secondary transfer position.

The paper discharge unit 70 is provided above the image forming unit 20, and includes a first stacking tray 71 for stacking sheets on which images are formed by the image forming unit 20, and the first stacking tray 71 and the image reading unit. And a second stacking tray 72 which is provided between the apparatus 100 and stacks sheets on which images are formed by the image forming unit 20.
The paper discharge unit 70 is provided downstream of the fixing device 45 in the transport direction, and is provided on a transport roll 75 that transports the paper P on which the toner image is fixed, and on the downstream side of the transport roll 75 in the transport direction. And a switching gate 76 for switching the transport direction of the paper P. In addition, the paper discharge unit 70 supplies the paper P, which is transported to one side (right side in FIG. 3) of the transport direction switched by the switching gate 76, to the first stacking tray 71 downstream of the switching gate 76 in the transport direction. A first discharge roll 77 for discharging is provided. In addition, the paper discharge unit 70 includes, on the downstream side in the transport direction of the switching gate 76, a transport roll 78 that transports the paper P transported to the other side (upper side in FIG. 3) of the transport direction switched by the switching gate 76. And a second discharge roll 79 for discharging the paper P conveyed by the conveyance roll 78 to the second stacking tray 72.

  The reverse conveyance unit 80 conveys the reversed paper P to the side of the fixing device 45 by rotating the conveyance roll 78 in the direction opposite to the direction in which the paper P is discharged to the second stacking tray 72. A reverse conveyance 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 transported by these transport rolls 82 is sent again to the secondary transfer position by the transport rolls 82.

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

The image recording apparatus 200 includes a front cover 15 that is provided on the front side of the image forming unit 20 as a part of the apparatus housing 12 and that can be opened and closed with respect to the apparatus main body frame 11.
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 by opening the front cover 15.

  The user interface 300 is a touch panel, for example. 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. In addition, the user performs input operations such as image forming conditions by touching the touch panel.

<Functional configuration example of control device>
FIG. 4 is a block diagram showing a signal processing system in the control device 900. Here, among the various functions of the control device 900, those related to signal processing are selected and shown.
The control device 900 acquires a data acquisition unit 91 that acquires image data created to output an image by the image recording device 200, and PDL generation that receives the image data and converts it into a page description language (PDL). 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 performs color adjustment of the CMYK data An adjustment unit 95, a color processing unit 96 that creates a profile for performing color adjustment by the color adjustment unit 95, a raster image adjustment unit 97 that adjusts a raster image converted by the color adjustment unit 95, and halftone processing A halftone processing unit 98 that performs the image conversion, and an image that outputs the color-converted image data to the image recording apparatus 200 And an image data output unit 99.

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

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

  The color conversion processing unit 94 converts the RGB data input from the rasterizing unit 93 into device-independent XYZ color values, and then reproduces the color (toner color as a color material: cyan (C ), CMYK data of magenta (M), yellow (Y), black (K)) and output. The 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 performs color adjustment of an image formed by the image recording apparatus 200. The color adjustment unit 95 adjusts the color of the CMYK data so as to match the target color that should be originally output from the image recording apparatus 200 in correspondence with the CMYK data. In the image forming apparatus 2, the color adjustment unit 95 is also used to perform color adjustment for obtaining an image that matches the color of the printed matter output from the image forming apparatus 1. This matter will be described later.
For color adjustment, for example, C _in M _in Y _in K _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 this embodiment, this conversion is performed by converting C _in M _in Y _in K _in data into other color spaces such as L ^* a ^* b ^* color space and C _in M _in Y _in K _in data. It carried out by using a so-called device link profile that converts directly into _{C out M} out _Y out _K out data in the same CMYK color space. The color adjustment unit 95 stores the device link profile and performs color adjustment by applying the C _in M _in Y _in K _in data to the device link profile.
In the present embodiment, the color adjustment unit 95 functions as a color adjustment unit that performs color adjustment of an image formed by the image recording apparatus 200 of the image forming apparatus 2. The device link profile is an example of a conversion relationship, and can be created, for example, as a four-dimensional LUT (Look up Table).

  Although described in detail later, the color processing unit 96 creates a device link profile that is used for color adjustment by the color adjustment unit 95. The color processing unit 96 is an example of a color processing device. The color processing unit 96 is an example of a conversion relationship creating unit that creates a conversion relationship (device link profile) used for color adjustment by the color adjustment unit 95.

The raster image adjustment unit 97 performs γ conversion, definition processing, halftone processing, and the like on the C _out M _out Y _out K _out data input from the color adjustment unit 95, thereby recording a better image quality. Various adjustments are made as obtained with the apparatus 200.

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

  The image data output unit 99 outputs image data subjected to image processing such as color conversion processing to the image recording apparatus 200.

<Description of color processing unit>
Next, the color processing unit 96 of the image forming apparatus 2 will be described in detail. Here, a case will be described in which the color processing unit 96 performs color adjustment for an image that matches the color of the printed matter output from the image forming apparatus 1.
The color processing unit 96 creates a device link profile that is used for 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 a functional configuration of the color processing unit 96 according to 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 region group extraction unit 964, a CMYK image region group extraction unit 965, A color data acquisition unit 966, a color conversion unit 967, a main color range extraction unit 968, an L ^* C ^* H ^* image region group extraction unit 969, an L ^* a ^* b ^* image region group extraction unit 970, 1 correspondence relationship creation unit 971, second correspondence relationship acquisition unit 972, second correspondence relationship storage unit 973, and conversion relationship creation unit 974.

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

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

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

The CMYK image region group extraction unit 965 extracts an image region corresponding to the image region extracted by the L ^* C ^* H ^* image region group extraction unit 964 from the CMYK data. In other words, 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 color data (first color data) of the image G1 (first image) output from the image recording apparatus 200 of the image forming apparatus 1. This color data is acquired by, for example, reading this printed matter using the image reading apparatus 100 of the image forming apparatus 2. That is, the image reading unit 110 of the image reading apparatus 100 reads the chromaticity of the printed material and generates color data. As the color data, for example, L ^* a ^* b ^* data is used as data independent of the device. 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 an orthogonal coordinate color space with the lightness L ^* and the chromaticity a ^* and b ^{* of the} amount representing the color as axes.

The CCD provided in the image reading unit 110 normally reads an image with RGB data. However, the image reading unit 110 outputs color data of L ^* a ^* b ^* values by converting RGB to L ^* a ^* b ^* using a multi-dimensional table corresponding to the reading characteristics of the CCD after reading. Can do. This multidimensional table can use, for example, an ICC profile created according to the reading characteristics of the CCD.

The color conversion unit 967 performs color conversion on the L ^* a ^* b ^* data that is the color data acquired by the color data acquisition unit 966. Here, the L ^* a ^* b ^* data is converted into color values in the LCH color space to obtain L ^* C ^* H ^* data.

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

The L ^* C ^* H ^* image area group extraction unit 969 extracts an image area corresponding to the main color range extracted by the main color range extraction unit 968. That is, here, this image region 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 from the L ^* a ^* b ^* data. In other words, an image area at the same position as the image area extracted by the L ^* C ^* H ^* image area group extraction unit 969 is extracted from the L ^* a ^* b ^* data acquired by the color data acquisition unit 966.

The L ^* C ^* H ^* image region group extraction unit 964, the CMYK image region group extraction unit 965, the L ^* C ^* H ^* image region group extraction unit 969, and the L ^* a ^* b ^* image region 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 creation unit 971 creates a first correspondence that is a correspondence between image data and color data.
The first correspondence relationship, and CMYK data is image data, a color data (first color data) ^L * ^a * ^{b *} data (hereinafter, the first color data ^"L _* 1 ^{a *} to become ₁ b ^* ₁ data "and there is to say) and of correspondence _{^{(CMYK-L * 1 a *}} 1 b * 1). A detailed method for creating the first correspondence will be described later.

The second correspondence relationship acquisition unit 972 acquires a second correspondence relationship for the image recording apparatus 200 corresponding to the first relationship between the image data and the image forming apparatus 2.
The second correspondence relationship is as follows: CMYK data and color data (second color data) L ^* a ^* b ^* data (hereinafter, the second color data is referred to as “L ^* ₂ a ^* ₂ b ^* _2”. sometimes referred to as data ") and the corresponding relationship to become _{^{(CMYK-L * 2 a *}} 2 b * 2). The second correspondence relationship is stored in the second correspondence relationship storage unit 973, and the second correspondence relationship acquisition unit 972 acquires the second correspondence relationship from the second correspondence relationship storage unit 973.

The second correspondence relationship is created in advance and stored in the second correspondence relationship storage unit 973. Conventional methods can be used to create the second correspondence. For example, an image of a color patch that covers the entire color gamut of the image recording apparatus 200 of the image forming apparatus 2 is printed. Then, this is measured with a colorimeter or the like to obtain color data. Color data obtained this time is the second color data _{^{(L * 2 a * 2 b}} * 2 data). Therefore, the second correspondence relationship is obtained by associating the second color data with the image data for printing the color patch image.

  The conversion relationship creating unit 974 uses the first correspondence relationship and the second correspondence relationship so that the color of the image G2 (second image) becomes the color of the image G1 (first image). A conversion relationship for performing color adjustment of the image recording apparatus 200 is created.

Specifically, both the ^L * ^a * ^{b *} data of the first relationship and the second relationship _{^{(L * 1 a * 1 b}} * 1 data and _{^{L * 2 a * 2 b *}} 2 data) By comparison, a correspondence relationship between the CMYK data when the L ^* a ^* b ^* data matches is created. That is, the first correspondence relationship represents the relationship between CMYK data that is 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 relationship 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 images G1 and G2 to be printed usually do not have the same color because their device characteristics are different. However, the conversion relationship represents the relationship between CMYK data when the colors of images printed by the image forming apparatus 1 and the image forming apparatus 2 are the same. Therefore, if the CMYK data, which is image data, is converted using the conversion relationship, and printing is performed by the image forming apparatus 2 using the converted CMYK data, the color of the image G1 printed by the image forming apparatus 1 is the same. The image G2 is output. That is, by using this conversion relationship, color adjustment for outputting the printed matter by the image forming device 2 can be performed in accordance with 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. The device link profile is sent to the color adjustment unit 95, and the color adjustment unit 95 performs color adjustment of an image formed by the image recording apparatus 200 using the device link profile.

<Description of method for extracting main color range>
Next, a method in which the main color range extraction unit 963 and the main color range extraction unit 968 extract the main color range from the image data and the color data will be described.
As described above, the main color is a color mainly used for image data and color data. There are usually a plurality of such primary colors. The main color range is a color range that can be taken by the main color for an image region that takes the main color. In other words, even in the image area that takes the main color, the colors are not uniform, but there are variations. The main color range represents in what color range the color is included in the image area.

6A to 6D are diagrams illustrating a method in which the main color range extraction unit 963 and the main color range extraction unit 968 extract the main color range.
Among 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 character portion “F” and the background portion have different colors. For example, the letter “F” is green, and the background portion 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 an image. The image of this color data is composed of the letter “F” as in the case of the image G1.

FIG. 6C shows a case where the image data is converted to a histogram for each color value of L ^* , C ^* , and H ^* with respect to L ^* C ^* H ^* data after color conversion by the color conversion unit 962. .
Similarly, FIG. 6D shows color data (first color data) for L ^* C ^* H ^* data after color conversion by the color conversion unit 967 for each color value of L ^* , C ^* , H ^*. A case of a histogram is shown.
In FIG. 6C and FIG. 6D, the horizontal axis represents the color values of L ^* , C ^* , and H ^* , and the vertical axis represents the frequency (number of pixels). FIGS. 6C and 6D show histograms of L ^* , C ^* , and H ^* for the background portion of the letter “F”.

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

  In the example of FIG. 6, focusing on the background of the character “F”, the color of this part (for example, yellow) is the main color. However, focusing on the part of the character “F”, the color of this part (For example, green) may be the main color. In addition, if other colors are used in the images G1 and G2, these colors may be 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 those in the same image area (in this case, the background area of the letter “F”) do not necessarily match due to the effect of color conversion errors. 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, it can be seen that they are from the same image area. That is, in this case, when looking at FIG. 6C and FIG. 6D, the same image region (the same image region (L ^* , C ^* , H ^* ) for the main color range having a close frequency (number of pixels). In this case, it can be seen that this is from the background area of the letter “F”.

  That is, according to this method, the color conversion unit 962 and the color conversion unit 967 described above are not easily affected by the color conversion error. Further, when the image reading apparatus 100 reads the image G1 (first image) and obtains the color data (first color data), a positional shift may occur. Even if this positional shift occurs. Insensitive to that.

<Description of Method for Creating First Correspondence>
Next, a method in which the first correspondence creation unit 971 creates the first correspondence will be described. Here, the first correspondence is created in two steps, Step 1 and Step 2.

In Step 1, the first correspondence creation unit 971 associates the main color ranges of the image data and the color data, and creates a first correspondence that is a 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 is from the same image area (in this case, the background area of the letter “F”). Therefore, these main color ranges are associated. The first correspondence creation unit 971 includes the average value (CMYK data) of the pixel values of the image regions extracted by the CMYK image region group extraction unit 965 and the image extracted by the L ^* a ^* b ^* image region group extraction unit 970. The average value (L ^* a ^* b ^* data) of the pixel values in the area is associated. In addition, since there are usually a plurality of main colors, these are similarly associated. Thus a first correspondence between _{^{CMYK-L * 1 a * 1}} b * 1 can be created in the same image region.

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

However, the colors included in the image data cannot usually be said to cover the entire color gamut of the image forming apparatus 1. In stage Therefore Step1, the number of first corresponding relationship ^{_{(CMYK-L * 1 a *}} 1 b * 1) is usually less, not be said to create an accurate conversion relation of the number is sufficient in There are many cases. Therefore, in the next Step 2, a process for compensating for the shortage is performed.

FIGS. 7A to 7D are diagrams illustrating Step 2 when the first correspondence creating unit 971 creates the first correspondence.
The first correspondence creation unit 971 applies the image data and the color data (first color data) of the acquired image G1 to a color gamut wider than the color gamut occupied by the color data (first color data). And fitting to the first correspondence candidate prepared in advance.
FIG. 7A is a conceptual diagram showing a first correspondence candidate prepared in advance.
FIGS. 7 (a) first correspondence candidate shown in, for the entire gamut of the image forming apparatus 1 (region expressed by diamonds), the first correspondence relationship ^{_{(CMYK-L * 1 a *}} 1 b * 1 ) Candidates are prepared in advance.

And FIG. 7 (b) shows the first corresponding relationship obtained in ^{_{Step1 (CMYK-L * 1 a}} * 1 b * 1). In this case, the first correspondence relationship consists of six pieces of data.
In this embodiment, as shown in FIG. 7C, the image data shown in FIG. 7B and the acquired color data are obtained for the first correspondence relationship candidate shown in FIG. (First color data) is applied and synthesized.

  However, since the data included in FIGS. 7A and 7B are not necessarily consistent, not only are they applied, but matching processing is performed. For example, data included in FIG. 7B that is closer than a predetermined Euclidean distance is removed from FIG. 7A. Or the weight according to the Euclidean distance from each data contained in FIG.7 (b) is set, and each data contained in FIG.7 (b) is weighted with this weight.

FIG. 7D is a diagram showing the Euclidean distance d and the set weight w.
In FIG. 7D, the horizontal axis represents the Euclidean distance d, and the vertical axis represents the weight w. The relationship is w = 1 / (1 + d).
In this case, the set weight w becomes smaller as the Euclidean distance d from each data included in FIG. For example, when the Euclidean distance d is 0, the weight w is 0. In this case, the data shown in FIG. Further, the set weight w becomes larger as the Euclidean distance d from each data included in FIG. When the Euclidean distance d _{0 is} greater than the predetermined distance, the weight w is 1. When the weight w is 1, it is the same as when the weight w is not set.

In FIG. 7C, the positions of the data to be removed or weighted among the data included in FIG. 7A are indicated by D1 to D3.
In this way, the first correspondence creation unit 971 compensates for the shortage of the number of first correspondences in Step 1 and covers the entire color gamut of the image forming apparatus 1 (CMYK). _{^{-L * 1 a * 1 b *}} 1) to create a. That is, the first correspondence creation unit 971 first determines in step 1 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. As the correspondence relationship, a first correspondence relationship that partially covers the color gamut of the image forming apparatus 1 is created. Then, in the next Step 2, the first correspondence relationship prepared in advance is applied and matched with the first correspondence relationship that partially covers the color gamut of the image forming apparatus 1, thereby forming an image. A first correspondence relationship that covers the entire color gamut of the device 1 is created.

Note first correspondence relationship obtained in ^{_{Step1 (CMYK-L * 1 a}} * 1 b * 1) is, colors included in the image data, even if it is intended to cover the entire gamut of the image forming apparatus 1 possible. In this case, the above-described step 2 is not necessary. Therefore, a determination unit may be provided in the first correspondence creation unit 971 whether or not Step 2 processing is necessary, and it may be determined whether or not to perform Step 2 processing based on the determination result of the 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. The determination is made based on whether or not there is a divided region with a low frequency.

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

  For example, if it is known that the image G1 is output under conditions similar to those of JapanColor2011, those having the conditions of JapanColor2011 are included in the plurality of first correspondence candidates. In addition, a standard condition that is frequently used may be included. Alternatively, image forming apparatuses sold in the past may be included in typical conditions. Further, a plurality of first correspondence relationship 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 that matches 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 reads the document in the image reading apparatus 100. Is read, and the color adjustment is completed, and printing is executed by the image forming apparatus 2. Therefore, the user may not have specialized skills.
In the present embodiment, the first correspondence creation unit 971 creates the first correspondence by performing Step 2 described above. Accordingly, 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 can perform more accurate. Create a high conversion relationship. Therefore, even in such a case, the accuracy of color adjustment is unlikely to decrease.

<Description of Color Adjustment Procedure of Image Forming Apparatus 2>
Next, in the first embodiment, a procedure when the image forming apparatus 2 performs color adjustment for outputting the image G2 that matches the color of the image forming apparatus 1 will be described.

FIG. 8 is a flowchart illustrating a procedure when the image forming apparatus 2 performs color adjustment for outputting the image G2 that matches the color of the image forming apparatus 1 in the first embodiment. FIGS. 9A to 9I are diagrams showing actual processing performed at this time.
Hereinafter, description will be made with reference to FIGS. 5, 8 and 9.

  First, a printed material on which an image G1 (first image) output by the image forming apparatus 1 is printed and image data when the printed material 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 performs color conversion on the image data acquired by the image data acquisition unit 961 and converts it into L ^* C ^* H ^* data from the CMYK data (step 103: FIG. 9B).
The main color range extraction unit 963 creates a histogram as shown in FIG. 6C for the L ^* C ^* H ^* data after color conversion by the color conversion unit 962 and extracts the main color range (step 104). .
Further, 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 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 region group extraction unit 965 extracts an image region corresponding to the image region extracted by the L ^* C ^* H ^* image region group extraction unit 964 from the CMYK data (step 106: FIG. 9D). .

Next, the image reading device 100 of the image forming apparatus 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 uses this color data (first color data). 1 color data) is acquired (step 108: FIG. 9E). This image data is L ^* a ^* b ^* data.

Then the color conversion unit 967, the color data color data acquiring unit 966 has acquired color ^conversion, and the L ^* a * ^{b *} data and ^{L * C} * ^H * data (step 109: FIG. 9 (f)) .
Then, the main color range extraction unit 968 creates a histogram as shown in FIG. 6D for the L ^* C ^* H ^* data after the color conversion by the color conversion unit 967, 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. 9G, the background region of the character “F” is extracted.
Further, 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 from the L ^* a ^* b ^* data. (Step 112: FIG. 9 (h)).

Next, the first correspondence creation unit 971 associates the main color ranges of the image data and the color data, and is the first correspondence in Step 1 described above, which is the correspondence between the image data and the color data. A first correspondence is created (step 113). At this time, the first correspondence creation unit 971 uses an average value of pixel values in the background region of the character “F” (average data of CMYK data) and an L ^* a ^* b ^* image region group extraction unit 970. The average value of the pixel values in the extracted image region (average data of L ^* a ^* b ^* data) is associated. In the example of FIG. 9 (i), (C, M, Y, K) = (0, 11, 50, 0), and (L ^* , a ^* , b ^* ) = (85, 1, 26) Associate.

  Then, the first correspondence creation unit 971 applies and matches the first correspondence created in step 113 to the first correspondence candidate prepared in advance. Accordingly, the first correspondence creation unit 971 creates the first correspondence that covers the entire color gamut of the image forming apparatus 1 as the first correspondence in Step 2 described above (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 creating unit 974 creates a conversion relationship for performing color adjustment of the image recording apparatus 200 of the image forming apparatus 2 from the first correspondence relationship and the second correspondence relationship (step 116).
The conversion relationship creation unit 974 outputs this conversion relationship as a device link profile to the color adjustment unit 95 (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 based on the device link profile. As a result, the image G2 output from the image forming apparatus 2 matches the color of the image G1 output from the image forming apparatus 1.

[Second Embodiment]
FIG. 10 is a block diagram illustrating a functional configuration of the color processing unit 96 according to 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 a validity judgment 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. Accordingly, the validity determination unit 975 will be mainly described below.

11A to 11F are diagrams 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 the respective main color ranges. That is, the color of the background area of the character “F” is the main color, and the color of the character portion “F” is the main color. Hereafter, the former may be referred to as “first primary color” and the latter as “second primary color”. In addition, the primary color ranges of the first primary color and the second primary color may be referred to as “first primary color range” and “second primary color range”.

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

FIG. 11C shows the first main color range extracted by the main color range extraction unit 963 based on the histogram of FIG.
FIG. 11D shows the first main color range extracted by the main color range extraction unit 968 based on the histogram of FIG.
Further, FIG. 11E shows the second main color range extracted by the main color range extraction unit 963 based on the histogram of FIG.
FIG. 11F shows the second main color range extracted by the main color range extraction unit 968 based on the histogram of FIG.
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.

  When comparing the first main color range of FIGS. 11C and 11D, the background area of the character “F” is wide in image area, and therefore has a high frequency (number of pixels). For this reason, a clear peak occurs for the first primary color, and therefore the first primary color range can be obtained with high accuracy.

  On the other hand, when comparing the second main color range of FIGS. 11 (e) and 11 (f), although a clear peak occurs in FIG. 11 (e) which is a histogram for the image data, the color data (first It can be seen that no clear peak occurs in FIG. 11 (f) which is a histogram for (color data). This obtains the color data (first color data) of the image G1 (first image), and therefore various noises are added when the image G1 is read using the image reading device 100 of the image forming apparatus 2. This is because it is easy. In particular, the area of the letter “F” has a narrow image area, and therefore the frequency (number of pixels) is small, the peak height 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 is difficult to obtain the second main color range with high accuracy, and the accuracy of the first correspondence relationship tends to decrease.

12A to 12D are diagrams illustrating other examples in which noise is easily added when the image G1 is read using the image reading apparatus 100 of the image forming apparatus 2.
Of these, FIGS. 12A to 12B show a case where the image G1 is an image subjected to screen processing.
FIG. 12A shows a histogram of the image G1 and the image data. In this case, the image G1 is uniform gray, and the histogram of the image data that is the basis of the image G1 shows a clear peak.
On the other hand, FIG. 12B shows a color data histogram and color data (first color data) obtained by reading the image G1 with the image reading apparatus 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 apparatus 100 has color variations. As a result, the histogram of this color data does not show a clear peak.

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

Therefore, in the second embodiment, a 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 whether or not to associate each main color range from 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. Determine and determine the primary color range used to create the first correspondence.

FIGS. 13A to 13D are diagrams illustrating a method for determining the validity of whether or not the validity determination unit 975 associates each main color range.
Among 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. FIG. 13B 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 968 based on the color data. That is, FIGS. 13A and 13B show the frequency (number of pixels) and the range of colors that can be taken in the background area of the character “F”.

  The similarity of the frequency (number of pixels) is used as a reference for determining the similarity of the characteristics of the pixels constituting each first primary color. In this case, in FIG. 13A, the frequency (number of pixels) that falls within the first main color range is 652. In FIG. 13B, the frequency (number of pixels) that falls within the first main color range is 667. If the difference in frequency (number of pixels) is within a predetermined threshold range, it is determined that the similarity is high, and if it exceeds the threshold, it is determined that the similarity is low.

  FIG. 13C shows the frequency (number of pixels) and the second main color range for the second main color extracted by the main color range extraction unit 963 based on the image data. FIG. 13D shows the frequency (number of pixels) and the second main color range for the second main color extracted by the main color range extraction unit 968 based on the color data. That is, FIGS. 13C and 13D show the frequency (number of pixels) and the range of colors that can be taken in the area of the character “F”.

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

  In the example described above, 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, the image data or the color data (first color data) is binarized, and the difference in the frequency (number of pixels) of the pixel values “0” or “1” is within a predetermined threshold range. That is, it is determined that the similarity is high, and if the threshold is exceeded, it is determined that the similarity is low. 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 if appropriate, this primary color range is used to create the first correspondence. If this is not the case, this primary color range is used to create the first correspondence. Thereby, the first correspondence relationship can be obtained with higher accuracy, and a conversion relationship with higher accuracy can be created.

  Next, in the second embodiment, a procedure when the image forming apparatus 2 performs color adjustment for outputting the image G2 that matches the color of the image forming apparatus 1 will be described.

FIG. 14 is a flowchart illustrating a procedure when the image forming apparatus 2 performs color adjustment for outputting the image G2 that matches the color of the image forming apparatus 1 in the second embodiment.
In FIG. 14, Step 201 to Step 210 are the same as Step 101 to Step 110 in FIG.
Thereafter, 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). ). Accordingly, the validity determination unit 975 determines a main color used to create the first correspondence relationship.

  Thereafter, 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 color determined in step 211.

[Third Embodiment]
FIG. 15 is a block diagram illustrating a functional configuration of the color processing unit 96 according to 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 a frequency calculation unit 976 is added. .
In the third embodiment, the functions of the processing units 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 for the image data by the main color range extraction unit 963. When the main color range extraction unit 968 extracts the main color range from the color data, the main color range extraction unit 968 sets the peak color range having the frequency (number of pixels) close to the frequency (number of pixels) calculated by the frequency calculation unit 976 as the main 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.

FIGS. 16A to 16B 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 arrow in FIG. 16A as the main color range. In this case, the range shown in the lower table of FIG. 16A is extracted as the main color range.
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 a 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 arrows.

  According to the third embodiment, the main color range extracted for the image data by the main color range extraction unit 963 and the main color range extracted for the color data by the main color range extraction unit 968 can be more easily associated with each other. .

  Next, in the third embodiment, a procedure when the image forming apparatus 2 performs color adjustment for outputting the image G2 that matches the color of the image forming apparatus 1 will be described.

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

Further, Steps 306 to 310 are the same as Steps 105 to 109 in FIG.
The main color range extraction unit 968 then extracts a 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).
Note 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 apparatus 100 is built in the image forming apparatus 2, but each may be a separate unit and the image reading apparatus 100 may be an independent apparatus.
Similarly, the control device 900 is built in the image forming apparatus 2, but 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. May be. In this case, the function of the color processing unit 96 can be realized by software (program) operating on 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 the claims that various modifications or improvements added to the above embodiment are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1, 2 ... Image forming apparatus 96 ... Color processing part 100 ... Image reading apparatus 200 ... Image recording apparatus 900 ... Control apparatus 961 ... Image data acquisition part 962, 967 ... Color conversion part, 963, 968 ... Main color range extraction unit, 964, 969 ... L ^* C ^* H ^* image region group extraction unit, 965 ... CMYK image region group extraction unit, 966 ... Color data acquisition unit, 970 ... L ^* a ^* b ^* Image region group extraction 971 ... first correspondence creation unit, 972 ... second correspondence acquisition unit, 973 ... second correspondence storage unit, 974 ... conversion creation unit, S ... image forming system

Claims (8)

A color data acquisition unit that acquires color data of the first image output by the first image forming unit based on the image data;
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 a color mainly used;
A first correspondence creation unit that associates the main color ranges of the image data and the color data and creates a first correspondence that is a correspondence between the image data and the color data;
A color processing apparatus comprising:   The main color range extraction unit is used to create the first correspondence relationship from the similarity of characteristics of 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 is determined.   The color processing according to claim 1, wherein the main color range extraction unit determines a main color range of the color data based on the number of pixels included in the main color range of the image data. apparatus. Based on the main color range, further comprising a region group extraction unit that extracts a specific region on the image as a region group,
4. The method according to claim 1, wherein the image data and the color data in the region group are used to create the first correspondence relationship by the first correspondence relationship creation unit. 5. The color processing apparatus as described.   From the first correspondence relationship and the second correspondence relationship for the second image forming means corresponding to the first correspondence relationship, the second image forming means output by the second image forming means based on the image data. 2. The image forming apparatus according to claim 1, further comprising a conversion relationship creating unit that creates a conversion relationship for performing color adjustment of the second image forming unit so that the color of the second image becomes the color of the first image. 5. The color processing apparatus according to any one of items 4 to 4.   The first correspondence relationship is created by fitting and matching the image data with the acquired color data of the first image with respect to a first correspondence relationship candidate prepared in advance. The color processing apparatus according to claim 1, wherein the color processing apparatus is a color processing apparatus. Second image forming means for forming an image on a recording material based on image data;
Color adjusting means for adjusting the color of an image formed by the second image forming means;
Conversion relation creating means for creating a conversion relation used for performing color adjustment in the color adjusting means;
With
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 unit based on the image data;
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 a color mainly used;
A first correspondence creation unit that associates the main color ranges of the image data and the color data and creates a first correspondence that is a correspondence between the image data and the color data;
Based on the image data, the second image forming means outputs the first correspondence relation and the second correspondence relation for the second image forming means corresponding to the first correspondence relation. A conversion relationship creating unit that creates a conversion relationship for performing color adjustment of the second image forming means so that the color of the second image becomes the color of the first image;
An image forming apparatus comprising: First image forming means for forming an image on a recording material based on image data;
Second image forming means for forming an image on a recording material based on the image data;
Color adjusting means for adjusting the color of an image formed by the second image forming means;
Conversion relation creating means for creating a conversion relation used for performing color adjustment in the color adjusting means;
With
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 unit based on the image data;
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 a color mainly used;
A first correspondence creation unit that associates the main color ranges of the image data and the color data and creates a first correspondence that is a correspondence between the image data and the color data;
Based on the image data, the second image forming means outputs the first correspondence relation and the second correspondence relation for the second image forming means corresponding to the first correspondence relation. A conversion relationship creating unit that creates a conversion relationship for performing color adjustment of the second image forming means so that the color of the second image becomes the color of the first image;
An image forming system comprising: