JP2006345448A - Image forming apparatus, method and program for controlling thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve highly precise image formation by efficiently correcting a color profile. <P>SOLUTION: This image forming apparatus has a color sensor 1 which detects chromaticity of an image formed on recording paper and an image formation part which forms an image for inspection on the recording paper, acquires target chromaticity by detecting target chromaticity of the image by the color sensor 1, acquires chromaticity of the image for inspection by detecting chromaticity of the image for inspection formed by the image formation part by the color sensor 1 based on chromaticity data of the target chromaticity and calculates coordinates on a color space for achieving the target chromaticity based on the target chromaticity and the chromaticity of the image for inspection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, a control method thereof, and a control program thereof.

  2. Description of the Related Art Conventionally, a color image is widely output by an output device such as a color printer or a printing machine based on an original image generated by a computer. At this time, for example, when trying to output a color image that is similar in color to a specific printed matter, or when trying to output a color image having a desired color expression from the output device, the output device It is important how the color data included in the input image data is expressed on the color image.

Such a correspondence between the input color data and the color on the output image is called a profile of the output device. To create a profile of the color image forming apparatus, for example, a computer forms a color chart composed of color patches in which halftone dots are sequentially changed for each of the four colors C, M, Y, and K. Next, each of the output color patches is measured by a colorimeter, and the color data sent to the printing machine for color chart output and the color chart obtained by measuring the color chart are determined by CIE, for example. A correspondence relationship (profile) with a chromaticity value such as an XYZ value of the XYZ color system being used is obtained. As a profile calculation method, for example, there are the following methods. That is, first, corresponding to each side on a solid (a solid corresponding to a cube in the case of three dimensions) defining the outer shape of a region (color reproduction region) to be expressed by the printing machine in the CMYK color space. The correspondence between color data and chromaticity values is obtained. Next, a correspondence relationship between the color data and the chromaticity value corresponding to each coordinate point on each surface surrounded by a plurality of sides is obtained. Finally, the calculation method is to obtain the correspondence between color data and chromaticity values corresponding to each coordinate point in the solid. By using the profile created in this way, it is possible to print a color image of a desired color expression using a printing machine (see, for example, Patent Document 1).
JP-A-10-126633

  However, in order to obtain the profile of the output device using the above-described method, it is necessary to measure the color by outputting a color chart composed of several hundred color patches using the output device. Further, in the color image forming apparatus, when there is a change in each part of the apparatus due to an environmental change or a long-time use, the density of the obtained image changes. In particular, in the case of an electrophotographic color image forming apparatus, density fluctuations may occur depending on environmental fluctuations and usage conditions, and color balance may be lost. Therefore, calibration must be performed periodically.

  Also, it is not necessary for some users to improve the color reproducibility of the entire area in the color space. In many cases, the color to be reproduced (target chromaticity) is about several colors. It is not practical to go and modify the color profile.

  The present invention has been made to solve the above-described problems of the prior art, and an object thereof is to efficiently calibrate a color profile and realize high-precision image formation.

In order to achieve the above object, an apparatus according to the present invention provides:
Detection means for detecting the chromaticity of the image formed on the recording medium;
Inspection image forming means for forming an inspection image on a recording medium;
By detecting the chromaticity of the target image by the detection means, the target chromaticity is acquired,
Based on the chromaticity data of the target chromaticity, the inspection image chromaticity is acquired by detecting the chromaticity of the inspection image formed by the inspection image forming unit by the detection unit,
Control means for calculating coordinates on a color space for achieving the target chromaticity based on the target chromaticity and the inspection image chromaticity;
It is characterized by providing.

In order to achieve the above object, the method according to the present invention comprises:
Detection means for detecting the chromaticity of the image formed on the recording medium;
Inspection image forming means for forming an inspection image on a recording medium;
An image forming apparatus control method comprising:
A target chromaticity acquisition step of acquiring the target chromaticity by detecting the chromaticity of the target image by the detection means;
An inspection image for obtaining the inspection image chromaticity by detecting the chromaticity of the inspection image formed by the inspection image forming unit based on the chromaticity data of the target chromaticity by the detection unit. A chromaticity acquisition step;
A calculation step of calculating coordinates on a color space for achieving the target chromaticity based on the target chromaticity and the inspection image chromaticity;
It is characterized by providing.

In order to achieve the above object, a program according to the present invention provides:
Detection means for detecting the chromaticity of the image formed on the recording medium;
Inspection image forming means for forming an inspection image on a recording medium;
An image forming apparatus control program comprising:
A target chromaticity acquisition step of acquiring the target chromaticity by detecting the chromaticity of the target image by the detection means;
An inspection image for acquiring the inspection image chromaticity by detecting the chromaticity of the inspection image formed by the inspection image forming unit based on the chromaticity data of the target chromaticity by the detection unit. A chromaticity acquisition step;
A calculation step of calculating coordinates on a color space for achieving the target chromaticity based on the target chromaticity and the inspection image chromaticity;
Is executed by an image forming apparatus.

  According to the present invention, it is possible to efficiently calibrate a color profile and realize high-precision image formation.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the constituent elements described in this embodiment are merely examples, and are not intended to limit the scope of the present invention only to them.

(First embodiment)
<Overview>
The first embodiment of the present invention relates to an output device such as a color printer or a printing machine that outputs a color image based on image data including color data, and coordinates in a color space that is the basis of the color image output. Is corrected to an appropriate value to express a desired color on the color image.

<Configuration>
FIG. 1 is a diagram showing an internal configuration of an electrophotographic color laser beam printer 100 as a first embodiment of an image forming apparatus according to the present invention. The printer 100 is a tandem color printer that employs an intermediate transfer member 27. 1 is a color sensor as a detecting means for detecting the chromaticity of an image formed on a recording medium, 2a is a recording paper as a recording medium used during normal image formation or inspection image formation, and 3a is during normal image formation Or, it is a paper feed cassette used when forming an image for inspection. 2b is a recording sheet as a recording medium on which an image having a target chromaticity is printed. 3b is used when a recording sheet on which an image having a target chromaticity is printed. It is a paper feed tray.
First, at the time of normal image formation, the recording paper 2a is fed from the paper feed cassette 3a to perform the image forming operation.

  When performing the color stabilization control, the recording paper 2b on which an image having the target chromaticity is printed is fed by the paper feed tray 3b, and the target chromaticity is detected by the color sensor 1. Next, the recording paper 2a is fed from the paper feed cassette 3a, an inspection image corresponding to the obtained target chromaticity detection result is formed on the recording paper 2a, and color stabilization control is performed.

  First, a normal image forming operation and a main body configuration will be described in detail. The recording paper 2a fed from the paper feed cassette 3a is conveyed in the direction of arrow P by the feed roller 4. An electrostatic latent image is formed on each photosensitive drum 22 by exposure light controlled by an image processing unit (not shown) based on an image signal at a timing synchronized with the transported paper. A single color toner image is formed by developing with the corresponding color toner, and this single color toner image is superimposed on the intermediate transfer member 27 to form a multicolor toner image. This multicolor toner image is transferred to the recording paper 2a. The multicolor toner image on the recording paper 2a is fixed by a fixing unit to form an image.

This image forming unit constitutes sheet feeding units 3a and 3b, photosensitive members (hereinafter referred to as photosensitive drums) 22Y, 22M, 22C and 22K corresponding to the stations arranged in parallel by the number corresponding to the number of colors of the developing color, and charging means. Chargers 23Y, 23M, 23C, and 23K, toner cartridges 25Y, 25M, 25C, and 25K, developing devices 26Y, 26M, 26C, and 26K constituting developing means, an intermediate transfer member 27, a transfer roller 28, and a fixing unit 30 are provided. Yes. The image forming unit functions as an inspection image forming unit that forms an inspection image on a recording sheet.
Here, each of the photosensitive drums 22Y, 22M, 22C, and 22K is configured by applying an organic optical transmission layer to the outer periphery of the aluminum cylinder, and the driving force of a driving motor (not shown) is transmitted to the photosensitive drums 22Y, 22M. , 22C and 22K are rotated counterclockwise in accordance with the image forming operation. Chargers 23Y, 23M, 23C, and 23K for charging the photosensitive drums 22Y, 22M, 22C, and 22K for yellow (Y), magenta (M), cyan (C), and black (K), respectively, are provided for each station. Each charger is provided with sleeves 23YS, 23MS, 23CS, and 23KS. Exposure light to each of the photosensitive drums 22Y, 22M, 22C, and 22K is sent from the corresponding scanner units 24Y, 24M, 24C, and 24K, respectively. Each exposure light selectively exposes the surface of each photosensitive drum 22Y, 22M, 22C, 22K, thereby forming an electrostatic latent image.

  Further, in order to visualize the electrostatic latent image on the photosensitive drum, each station develops each of the developing devices 26Y, 26M, which develop yellow (Y), magenta (M), cyan (C), and black (K). 26C, 26K. Each developing device is provided with a sleeve 26YS, 26MS, 26CS, and 26KS. Here, each developing device is detachably attached to the printer 100. Further, the intermediate transfer member 27 is in contact with the photosensitive drums 22Y, 22M, 22C, and 22K. When a color image is formed, it rotates in the direction of arrow I as the photosensitive drums 22Y, 22M, 22C, and 22K rotate. The toner images of the respective colors are transferred onto the intermediate transfer member 27 in an overlapping manner. Thereafter, the transfer roller 28 comes into contact with the intermediate transfer member 27 (position indicated by 28a), and the recording paper 2a is nipped and conveyed by the transfer roller 28 and the intermediate transfer member 27, and is transferred to the recording paper 2a on the intermediate transfer member 27. The multicolor toner image is transferred. The transfer roller 28 contacts the recording paper 2a at a position indicated by 28a while the multicolor toner image is being transferred onto the recording paper 2a, and is separated to a position indicated by 28b after the transfer process.

  The fixing unit 30 melts and fixes the multicolor toner image transferred to the recording paper 2a while transporting the recording paper 2a. As shown in FIG. 1, the fixing roller 31 and the recording paper 2a for heating the recording paper 2a. Is provided with a pressure roller 32 for bringing the toner into pressure contact with the fixing roller 31. Here, the fixing roller 31 and the pressure roller 32 are formed in a hollow shape, and heaters 33 and 34 are incorporated therein, respectively. That is, the recording paper 2a holding the multicolor toner image is conveyed by the fixing roller 31 and the pressure roller 32, and heat and pressure are applied to fix the toner on the surface of the recording paper 2a. After the toner image is fixed in this way, the recording paper 2a is discharged to the paper discharge tray 5 by the rotation of the discharge roller 4, and the image forming operation is completed. The cleaner 29 removes the toner remaining on the intermediate transfer member 27. The waste toner thus removed is stored in a cleaner container (not shown).

  FIG. 2 is a flowchart showing processing of the image processing unit according to the first embodiment. In step S201, an RGB signal sent from a host computer or the like is converted into a device RGB signal (hereinafter referred to as DevRGB) that matches the color gamut of the printer 100 using a color matching table prepared in advance. In step S202, the DevRGB signal is converted into a CMYK signal that is a toner color material color of the printer 100 using a color conversion table prepared in advance. In step S203, the CMYK signal is corrected and converted into a C'M'Y'K 'signal by using a density correction table for correcting the tone-density characteristics specific to the printer. In step S204, halftone processing such as dithering is performed and converted to a C "M" Y "K" signal. If one pixel is multi-valued, the exposure times Tc, Tm of the scanner units 24C, 24M, 24Y, 24K corresponding to the C "M" Y "K" signal are determined in step S205 according to the PWM (Pulse Width Modulation) table. , Ty, Tk are output.

  As shown in FIG. 1, the color sensor 1 is disposed downstream of the fixing unit 30 in the conveyance path of the recording paper 2a toward the image forming surface of the recording paper 2a. FIG. 3A is a diagram illustrating an exemplary configuration of the color sensor 1. The color sensor 1 includes a white LED 301 and a charge storage sensor 302 with an RGB on-chip filter. The white LED 301 makes white light incident at an angle of 45 degrees with respect to the recording paper 2 a on which the patch 304 after fixing is formed, and the charge accumulation type sensor 302 detects the intensity of diffusely reflected light in the 0 degree direction. The light receiving unit 303 of the charge storage type sensor 302 with the RGB on-chip filter is an independent pixel for RGB as shown in FIG.

  The charge storage type sensor used in the light receiving unit 303 may be configured with a photodiode. As another configuration, a configuration in which the incident angle is 0 degree and the reflection angle is 45 degrees may be used. Furthermore, you may comprise by LED which emits RGB three colors, and a sensor without a filter.

  The color sensor 1 obtains RGB values from the patch after fixing formed on the recording paper 2a. Hereinafter, RGB values as measurement values obtained by the color sensor 1 are abbreviated as “sensor RGB values”. The sensor RGB values are converted into chromaticity information by mathematical processing such as linear conversion. Based on this chromaticity information, control according to the density or chromaticity of the patch after fixing formed on the recording paper 2a is performed. As described above, it is possible to automatically detect the density and chromaticity of the patch image transferred and fixed on the recording paper 2a before discharging the fixed image to the paper discharge unit.

<Color stabilization processing>
Next, the color stabilization process will be described. A program for executing the color stabilization process is stored in the ROM of the color printer main body, and functions as control means when a control unit (not shown) executes the program. Specifically, the target chromaticity is obtained by detecting the chromaticity of the target image by the color sensor 1, and based on the chromaticity data of the target chromaticity, an inspection image formed by the image forming unit. By detecting the chromaticity of the image by the color sensor 1, the image chromaticity for inspection is acquired, and further, on the color space for achieving the target chromaticity based on the target chromaticity and the image chromaticity for inspection. The coordinates of are calculated.
FIG. 4 is a flowchart for explaining the color stabilization process using the color sensor 1. The color stabilization process will be described more specifically using this flowchart.

  First, in step S401, the recording paper 2b on which an image having the target chromaticity is printed is fed from the paper feed tray 3b. FIG. 5 shows a correspondence relationship between the position of the color sensor 1 and the recording sheet 2b on which the color 501 serving as the target chromaticity is printed. The target chromaticity to be reproduced in the recording paper 2b is the color of the portion indicated by 501.

  In step S402, the color sensor 1 detects the color 501 that is the target chromaticity. At this time, since the position of the color sensor 1 is fixed, color information on a straight line on which the color sensor 1 is installed can be detected as shown in FIG.

  Next, in step S403, the user sets the target chromaticity. Specifically, as shown in FIG. 6, the color information read in step S402 is output to the display of the host computer (the information output at this time is for the purpose of grasping the positional relationship for the user. The color does not need to be accurately reproduced above). The user designates the portion of the target chromaticity to be reproduced on the display of the host computer as indicated by 502 in FIG.

  In step S404, the sensor RGB value St (Rt, Gt, Bt) of the color 502 that is the target chromaticity output from the color sensor 1 is stored in the memory.

  Next, in step S405, combinations (Cn, Mn, Yn, Kn) of colors C, M, Y, K that can achieve the sensor RGB value St (Rt, Gt, Bt) with the color matching table of FIG. calculate. If the image formation conditions are exactly the same as those at the time of color processing design, the color of the sensor RGB value St (Rt, Gt, Bt) matches the color mixed with (Cn, Mn, Yn, Kn). As described in the prior art, due to the influence of environmental and machine durability fluctuations, the colors do not match completely and the colors are shifted.

  Next, in step S406, an inspection image patch is formed. The inspection image patch uses a plurality of patches based on (Cn, Mn, Yn, Kn) and having a fixed color Kn and varying the color mixing ratio of C, M, and Y. The reason for fixing Kn will be described below.

  The color printer 100 described in this embodiment forms a full-color image by mixing cyan, magenta, yellow, and black. In this case, a * and b * in the L * a * b * space are controlled by the color mixture ratio of cyan, magenta, and yellow to improve the reproducibility of a * and b * that are conspicuous to human eyes. Therefore, it is essential to control the balance of the gradation levels of cyan, magenta, and yellow with high accuracy. On the other hand, L *, which greatly depends on the color mixture ratio of black, is relatively stable and its fluctuation is not noticeable to human eyes. For the above reasons, the printer shown in the present embodiment fixes Kn and changes the color mixture ratio of cyan, magenta, and yellow.

  However, the present invention is not limited to this, and control for increasing the number of patches, changing the calculation formula to adjust the color mixing ratio of K, and further improving reproducibility for L * may be performed.

  FIG. 7 shows the color mixture rate of the color mixture patch. The C, M, and Y gradation levels of the nine CMYK mixed color patches 0 to 8 are combinations of CMYK reference values (Cn, Mn, Yn, Kn) and a value ± α obtained by changing the gradation degree of a specific color. It has become. The nine patches whose colors are determined in this way are formed on the recording paper as shown in FIG.

  The RGB output of the patch fixed on the transfer material in step S407 is detected by the color sensor 1, and the C, M, and Y levels for achieving the sensor RGB value St (Rt, Gt, Bt) from the RGB output value of the sensor. Calculate the furniture. The RGB output values of each patch are S0 = (r0, g0, b0), S1 = (r1, g1, b1), S2 = (r2, g2, b2),. If the M and Y coordinates are represented three-dimensionally, they become 900 to 908 in FIG. The coordinates of the center of the cubic lattice in the figure are white circles represented by 900 in the figure, and are measured values corresponding to the inspection image patches (Cn, Mn, Yn).

  From the RGB values of S0 to S8, C, M, and Y values for matching with the sensor RGB value St (Rt, Gt, Bt) are obtained by 8-point linear interpolation excluding S0. Specifically, the RGB values (Rcmy, Gcmy, Bcmy) for the C, M, and Y coordinates in the cubic lattice of FIG. 8 are calculated by the following equations.

RCmy = [(C-Cn + α) (M-Mn + α) (Y-Yn + α) r1 +
(Cn + α-C) (M-Mn + α) (Y-Yn + α) r2 +
(C-Cn + α) (Mn + α-M) (Yn + α-Y) r3 +
(C-Cn + α) (M-Mn + α) (Yn + α-Y) r4 +
(Cn + α-C) (Mn + α-M) (Y-Yn + α) r5 +
(Cn + α-C) (M-Mn + α) (Yn + α-Y) r6 +
(C-Cn + α) (M-Mn + α) (Yn + α-Y) r7 +
(Cn + α-C) (Mn + α-M) (Yn + α-Y) r8] / (8α ³ )
Gcmy and Bcmy are also obtained by the same formula.

  The difference between (Rcmy, Gcmy, Bcmy) calculated by the above equation and the target RGB value St (Rt, Gt, Bt) is obtained by, for example, the sum of squares of the differences of each RGB. Then, the one having the smallest difference, that is, (Rcmy, Gcmy, Bcmy) closest to the target RGB value St (Rt, Gt, Bt) is obtained, and the values of C, M, Y at this time are set as optimum values (Cn ′, Mn ′, Yn ′).

  That is, the combination of C, M, Y, and K that outputs the color closest to the target RGB value St (Rt, Gt, Bt) in the current color printer state that is finally calculated is (Cn ′, Mn ′). , Yn ′, Kn).

Α is
1) In order to increase the accuracy of interpolation, it is desirable that the size of the cubic lattice is as small as possible.

  2) When the colors of St (Rt, Gt, Bt) and (Cn, Mn, Yn, Kn) are greatly shifted, (Cn ′, Mn ′, Yn ′) is the center of the cubic lattice (Cn, Mn, Yn). In this case, (Cn ′, Mn ′, Yn ′) must be in the cubic lattice, and the cubic lattice needs to be sufficiently large.

  Considering the above two conditions, the optimum value is set.

  Finally, in step S409, the set value of (Cn ′, Mn ′, Yn ′, Kn) is returned to the host computer and notified to the user. Specifically, a message such as “recommended setting values (cyan, magenta, yellow, black) = (Cn ′, Mn ′, Yn ′, Kn)” is displayed through the driver software of the planter. When the user changes the color information of the original image according to the display (Cn ′, Mn ′, Yn ′, Kn), the user can print a sample of a desired color. As another configuration, the host computer may automatically update the color information of the original image.

  The above is the description of the calibration method for color reproduction in the present embodiment.

  The user can freely output the color desired to be reproduced by the color printer by operating the color information of the original image based on the value of (Cn ′, Mn ′, Yn ′, Kn) calculated in the above flow. However, the present invention is not limited to this, and instead of the information of (Cn ′, Mn ′, Yn ′, Kn), the information may be replaced with RGB information and notified to the user. At that time, DevRGB values may be specified in consideration of the conversion formula in the color conversion table 202 shown in FIG. 2, and further replaced with RGB information in consideration of the conversion formula in the color matching table 201 shown in FIG. Can be left to the user.

  In the present embodiment, a sheet feeding tray is provided as a sheet feeding unit used when feeding a recording sheet on which an image having a target chromaticity is printed, and the sheet feeding unit is used during normal image formation or inspection image formation. A paper cassette was provided. However, all of these may be unified into one sheet feeding means (for example, a sheet feeding cassette) used for normal image formation. At that time, the recording paper on which the image having the target chromaticity is printed must pass through the secondary transfer means and the fixing device, and depending on the type of the printed material, the gloss of the toner surface may be increased by passing through the fixing device. Since it may be increased, it is necessary to correct the target RGB value St.

  In the present embodiment, the above-described configuration and operation drastically reduce the labor and time required for color profile calibration control, and control that requires little user operation is possible.

(Second Embodiment)
In the present embodiment, a method for reproducing a color desired to be reproduced by a user with high accuracy using a document reading device (color scanner) of a copying machine instead of a color sensor as detection means will be described. This embodiment is an extension of the first embodiment. The most different point from the first embodiment is that a document reading device of a copying machine is used instead of a color sensor.

  Hereinafter, the color stabilization control as the second embodiment will be described in detail with reference to the drawings. FIG. 10 shows the configuration of a color copying machine as an example of an electrophotographic color image forming apparatus according to the second embodiment. A document reading apparatus 1000 that reads an image of the document 1001 is disposed on the upper part of the image forming apparatus main body. The document reading apparatus 1000 illuminates a document 1001 placed on a platen glass 1002 with a light source 1003, and reflects a reflected light image from the document 1001 from a full-rate mirror 1004, half-rate mirrors 1005 and 1006, and an imaging lens 1007. The image reading element 1008 made of a CCD or the like is scanned and exposed through a reduction optical system, and the color material reflected light image of the original 1001 is given three colors of R, G, and B at a predetermined dot density by the image reading element 1008. The sensor RGB values are converted.

  The converted sensor RGB values are subjected to image processing, and the following image processing similar to that of image data sent from a personal computer or the like is performed in the same process as in the first embodiment. Hereinafter, the image forming method and configuration of the color image forming apparatus used in the present embodiment are the same as those of the color image forming apparatus described in FIG.

  Next, color stabilization control will be described.

  FIG. 11 is a flowchart for explaining color stabilization control using the document reading apparatus 1000 in the color image forming apparatus according to the present embodiment. A program for executing this processing is stored in the ROM of the color image forming apparatus main body. Yes.

  First, in step S1101, the recording paper 2b on which an image having the target chromaticity is printed is set in the document reading apparatus 1000.

  In step S <b> 1102, the original reading apparatus 1000 detects the color 502 that is the target chromaticity. At this time, the document reading apparatus 1000 can detect color information of the entire document as shown in FIG.

  In step S1103, the user sets an image having target chromaticity. Specifically, as shown in FIG. 12, the color information read in step S1102 is output to the operation panel of the image forming apparatus. (At this time, since the information output is intended to grasp the positional relationship for the user, the color does not need to be accurately reproduced on the display, and may be a monochrome image.) Specify the target chromaticity part you want to reproduce on the operation panel.

  In step S1104, the sensor RGB value St (Rt, Gt, Bt) of the color 502 that is the target chromaticity and is output from the document reading apparatus 1000 is stored in the memory.

  Next, in step S1105, combinations (Cn, Mn, Yn, Kn) of colors C, M, Y, K that can achieve sensor RGB values St (Rt, Gt, Bt) in the color matching table of FIG. calculate. In step S1106, an inspection image patch is formed by the same method as in the first embodiment.

  The RGB output of the patch fixed on the transfer material in step S1107 is detected by the document reading apparatus 1000, and C, M, and Y for achieving the sensor RGB value St (Rt, Gt, Bt) from the RGB output value of the sensor. The gradation is calculated.

  In step S1106, optimum values (Cn ′, Mn ′, Yn ′) are derived by the same method as in the first embodiment.

  The color conversion table may use conventionally known grid point conversion. In this case, the color conversion table at the grid point in the vicinity of the color data indicated by 202 in FIG. 2 is corrected so that a desired chromaticity can be obtained. Note that the color matching table 201 in FIG. 2 may be corrected. The above is the description of the calibration method for color reproduction in the present embodiment. However, the present invention is not limited to this, and RGB information may be rewritten instead of (Cn ′, Mn ′, Yn ′, Kn) information. When the original image data is on the host computer, the setting values of (Cn ′, Mn ′, Yn ′, Kn) may be returned to the host computer and notified to the user as in the first embodiment. Specifically, the driver software of the planter is met and a message such as “recommended setting value (cyan, magenta, yellow, black) = (Cn ′, Mn ′, Yn ′, Kn)” is displayed. When the user changes the color information of the original image according to the display (Cn ′, Mn ′, Yn ′, Kn), the user can print a sample of a desired color.

(Other embodiments)
Although the embodiments of the present invention have been described in detail above, the present invention may be applied to a system constituted by a plurality of devices or may be applied to an apparatus constituted by one device.

  The present invention can also be achieved by supplying a program that realizes the functions of the above-described embodiments directly or remotely to a system or apparatus, and the system or apparatus reads and executes the supplied program code. The Accordingly, the program code itself installed in the computer in order to realize the functional processing of the present invention by the computer is also included in the technical scope of the present invention.

  In this case, the program may be in any form as long as it has a program function, such as an object code, a program executed by an interpreter, or script data supplied to the OS.

  As a storage medium for supplying the program, for example, floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, MO, CD-ROM, CD-R, CD-RW, magnetic tape, nonvolatile memory card ROM, DVD (DVD-ROM, DVD-R) and the like.

  As another program supply method, a client computer browser is used to connect to a homepage on the Internet, and the computer program itself of the present invention or a compressed file including an automatic installation function is downloaded from the homepage to a storage medium such as a hard disk. Can also be supplied. It can also be realized by dividing the program code constituting the program of the present invention into a plurality of files and downloading each file from a different homepage. That is, a WWW server that allows a plurality of users to download a program file for realizing the functional processing of the present invention on a computer is also included in the claims of the present invention.

  In addition, the program of the present invention is encrypted, stored in a storage medium such as a CD-ROM, distributed to users, and key information for decryption is downloaded from a homepage via the Internet to users who have cleared predetermined conditions. It is also possible to execute the encrypted program by using the key information and install the program on a computer.

  In addition to the functions of the above-described embodiments being realized by the computer executing the read program, the OS running on the computer based on an instruction of the program is a part of the actual processing. Alternatively, the functions of the above-described embodiment can be realized by performing all of them and performing the processing.

  Furthermore, after the program read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion board or The CPU or the like provided in the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

1 is a diagram illustrating a configuration of an electrophotographic color image forming apparatus according to a first embodiment of the present invention. It is a flowchart which shows the process of the image process part concerning 1st Embodiment of this invention. It is a figure which shows the color sensor concerning 1st Embodiment of this invention. It is a flowchart explaining the color stabilization control which concerns on 1st Embodiment of this invention. It is a figure which shows the correspondence of the recording paper on which the color used as target chromaticity was printed, and the position of a color sensor. It is a figure which shows the example of an image which read the recording paper on which the color used as target chromaticity was printed with the color sensor. It is a figure showing the color material mixing rate of the image patch for a test | inspection. It is a figure which shows the image patch for a test | inspection printed on the recording paper. It is the figure which expressed the C, M, Y coordinate of the image patch for a test | inspection three-dimensionally. It is a figure which shows the structure of the electrophotographic color copying machine which concerns on 2nd Embodiment of this invention. 6 is a flowchart illustrating color stabilization control using the document reading apparatus. It is a figure which shows the result of having read the recording paper in which the color used as target chromaticity was printed with the original reading apparatus. It is a figure which shows the image patch for a test | inspection printed on the recording paper.

Explanation of symbols

1 Color sensor 2a Recording paper 2b used for normal printing Recording paper 3a on which a color serving as a target chromaticity is printed Paper feeding unit 3b Paper feeding unit 22Y that feeds a recording paper on which a color serving as a target chromaticity is printed 22M, 22C, 22K Photosensitive drum (photoconductor)
23Y, 23M, 23C, 23K Charger 23YS, 23MS, 23CS, 23KS Sleeve 24Y, 24M, 24C, 24K Scanner unit 25Y, 25M, 25C, 25K Toner cartridge 26Y, 26M, 26C, 26K Developer 27 Intermediate transfer member 28a, 28b transfer roller 29 cleaning means 30 fixing unit 31 fixing roller 32 pressure rollers 33 and 34 heater 100 image forming apparatus P recording material conveyance direction I intermediate transfer member rotation direction 301 light emitting element 302 light receiving element 303 optical element 304 image patch pattern for inspection 501 Target chromaticity 502 Target chromaticity setting 900 to 908 Coordinate in CMY space corresponding to patches 0 to 8 Document reading apparatus 1001 Document 1002 Platen glass 1003 Light source 1004 Full-rate mirror 1005 Half-rate mirror 006 half-rate mirror 1007 half-rate mirror 1008 image reading device

Claims (9)

Detection means for detecting the chromaticity of the image formed on the recording medium;
Inspection image forming means for forming an inspection image on a recording medium;
By detecting the chromaticity of the target image by the detection means, the target chromaticity is acquired,
Based on the chromaticity data of the target chromaticity, the inspection image chromaticity is acquired by detecting the chromaticity of the inspection image formed by the inspection image forming unit by the detection unit,
Control means for calculating coordinates on a color space for achieving the target chromaticity based on the target chromaticity and the inspection image chromaticity;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the control unit notifies a user of coordinates on a color space for achieving the target chromaticity.   The image forming apparatus according to claim 1, wherein the control unit automatically corrects a color profile based on coordinates on a color space for achieving the target chromaticity.   The image forming apparatus according to claim 1, wherein the control unit displays an image detected by the detection unit on a display, and causes the user to select an image region representing target chromaticity.   The image forming apparatus according to claim 1, wherein the detection unit is a color sensor or a color scanner. Detection means for detecting the chromaticity of the image formed on the recording medium;
Inspection image forming means for forming an inspection image on a recording medium;
An image forming apparatus control method comprising:
A target chromaticity acquisition step of acquiring the target chromaticity by detecting the chromaticity of the target image by the detection means;
An inspection image for acquiring the inspection image chromaticity by detecting the chromaticity of the inspection image formed by the inspection image forming unit based on the chromaticity data of the target chromaticity by the detection unit. A chromaticity acquisition step;
A calculation step of calculating coordinates on a color space for achieving the target chromaticity based on the target chromaticity and the inspection image chromaticity;
An image forming apparatus control method comprising:   The method of controlling an image forming apparatus according to claim 6, further comprising a notifying step of notifying a user of coordinates in the color space calculated by the calculating step.   The method of controlling an image forming apparatus according to claim 6, further comprising a correction step of automatically correcting a color profile based on the coordinates on the color space calculated by the calculation step. Detection means for detecting the chromaticity of the image formed on the recording medium;
Inspection image forming means for forming an inspection image on a recording medium;
An image forming apparatus control program comprising:
A target chromaticity acquisition step of acquiring the target chromaticity by detecting the chromaticity of the target image by the detection means;
An inspection image for acquiring the inspection image chromaticity by detecting the chromaticity of the inspection image formed by the inspection image forming unit based on the chromaticity data of the target chromaticity by the detection unit. A chromaticity acquisition step;
A calculation step of calculating coordinates on a color space for achieving the target chromaticity based on the target chromaticity and the inspection image chromaticity;
And a control program for the image forming apparatus.

Images