JP2005268832A - Image forming apparatus and image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus for performing optimum calibration according to the status of color reproducing characteristic of the image forming apparatus by reducing a cost without using an expensive colorimeter device. <P>SOLUTION: This image forming apparatus has a function for evaluating the status of the image forming apparatus to perform the optimum calibration. The apparatus maintains a reference color to be reproduced in the reference status of an output device and a permissible value for each color of representative colors, obtains an evaluation value from the deviation quantity of the colorimetric value of a patch outputted in which a representative color is outputted by the output device and the reference color and the permissible value, and determines from the evaluation value and the permissible value whether the device characteristic information should be updated or not and the contents of the characteristic to be updated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and an image forming system, and more particularly to a calibration execution technique in a color image forming apparatus.

Conventionally, an image output device such as a color printer sometimes has different colors of an output image even if the same image is output due to a change in state of the internal mechanism of the device over time. The reason why the colors of the output image are different is that (1) the input / output characteristics (gamma characteristics) of each color material used for image formation fluctuate, and (2) the gradation pattern formed by each color material is overlapped. There are variations in color mixing characteristics that change the way the colors overlap.
In order to correct such variations, the apparatus is calibrated.

  Calibration for correcting the former variation is called gamma correction and has been proposed in various ways. For example, print out a balance chart consisting of multiple patches with a slight change in CMY (Cyan, Magenta, Yellow) and a reference reference chart, compare these printouts, and select patches that are visually color-matched Thus, a method of correcting the color conversion data (see Patent Document 1) has been proposed.

  In addition, for each of CMYK highlights, middle, and shadows, there is proposed a method (Patent Document 2) that performs adjustment by comparing a printed test chart with a reference reference chart and selecting patches of the same density. Yes.

As a calibration method for solving the latter problem, a method of updating a device profile (for example, ICC profile) describing color reproduction characteristics of an image forming apparatus is known. For example, Patent Document 3 proposes a method of outputting a predetermined representative color and determining the update timing from the color measurement result.
JP-A-9-321999 Japanese Patent Laid-Open No. 10-6562 JP 2003-87581 A

  However, in the above-described conventional technology, the device profile is not always updated when appropriate. The user regularly compares the display color on the color monitor with the output result from the color printer, This is done when it is judged necessary, and it is not clear whether the profile should be updated.

  For example, in Patent Document 3, some representative colors are measured, and it is determined whether or not the profile is updated based on the amount of color deviation from the set value. Since the color misregistration does not take into account whether the color misregistration is caused by gamma fluctuation or color mixing characteristic fluctuation, the profile may be unnecessarily updated even if the gamma fluctuation is caused.

  If the profile is updated unnecessarily in this way, not only is the cumbersome task of outputting a large number of patches and measuring the color performed when updating the profile unnecessary, As a result, the cost increased and the efficiency decreased.

  In addition, it is needless to say that the use of a colorimetric device is desirable in terms of accuracy in order to calibrate the color variation of the image forming apparatus (see Patent Document 3), but the colorimetric device is expensive. Actually, since it is impossible to provide all output devices, some devices do not include a colorimetric device. However, even in such an apparatus, it is required to perform an optimum calibration.

The present invention has been made in consideration of the above-described circumstances, and reduces the cost without using an expensive colorimetric device, and performs optimum calibration according to the state of the color reproduction characteristics of the image forming apparatus. An object of the present invention is to provide an image forming apparatus and an image forming system.
Another object of the present invention is to provide an image forming apparatus and an image forming system that allow a user to quickly take an appropriate response in accordance with a determination result relating to calibration contents.

  In order to achieve the above object, according to a first aspect of the present invention, in a color image forming apparatus having a calibration function, for each color of the representative color, a reference color and an allowable value reproduced by the image forming apparatus in a reference state A reference color calculation means for calculating a colorimetric result of a patch output by the image forming apparatus corresponding to the representative color, a deviation amount with respect to the reference color, and the deviation amount and the allowable value. Evaluation amount calculating means for obtaining an evaluation amount, and calibration content determining means for determining the presence / absence of calibration and the content of calibration to be performed based on the evaluation amounts for the plurality of representative colors.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, for the representative colors other than the primary color among the representative colors, the primary color required for forming the representative color is the image forming apparatus. The reference color is calculated from the color measurement result of the patch that is output more.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the permissible value is set for each hue, saturation, and lightness, and is a value that reflects visual characteristics. To do.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the evaluation amount is calculated by normalizing the deviation amount with the allowable value.

  According to a fifth aspect of the present invention, in a color image forming apparatus having a calibration function, a first reference chart composed of representative colors reproducible only with a primary color of the image forming apparatus, and the first reference chart A second reference chart including a representative color obtained by mixing primary colors corresponding to the representative colors, and colors within a predetermined range so as to include the representative colors given by the first reference chart. A plurality of swayed patches are output, color comparison with the first reference chart is performed, a patch closest in color to the first reference chart among the output patches is determined, and the determined primary A reference color calculation unit that outputs a patch obtained by mixing color patches, compares the output patch with the second reference chart, and determines a patch in the second reference chart that is closest in color; , Said size An evaluation quantity calculating means for calculating an evaluation value from the results, on the basis of the evaluation amount, and having a calibration content determining means determines the presence and implementation to calibrate the contents of the calibration performed.

  According to a sixth aspect of the present invention, in the image forming apparatus according to any of the first and fifth aspects, the calibration content determining means includes an evaluation amount for a primary color representative color and an evaluation amount for a representative color other than the primary color. The first calibration for updating the gamma characteristic is performed based on the comparison result, or the device profile information of the image forming apparatus is updated. It is characterized by determining whether to perform calibration.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the calibration content determining means has an evaluation amount for the representative color of the primary color within an allowable range, and the representative other than the primary color. When the evaluation amount for the color is out of the allowable range, the second calibration is performed.

  According to an eighth aspect of the present invention, in the image forming apparatus according to the sixth aspect, the calibration content determining means has an evaluation amount for the representative color of the primary color outside the allowable range, and the representative other than the primary color. When the evaluation amount for the color is within the allowable range, the first calibration is performed.

  According to a ninth aspect of the present invention, in the image forming apparatus according to the sixth aspect, the calibration content determining means has both an evaluation amount for the representative color of the primary color and an evaluation amount for the representative color other than the primary color. When it is outside the allowable range, the second calibration is performed after the first calibration.

  According to a tenth aspect of the present invention, in the image forming apparatus according to the sixth aspect, the calibration content determining means has both an evaluation amount for the representative color of the primary color and an evaluation amount for the representative color other than the primary color. When it is within the allowable range, the calibration is not performed.

  According to an eleventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the calibration content determination means has a second allowable value in which an evaluation amount for the primary color or the secondary color is different from the allowable range. When it is out of range, the image forming apparatus determines that calibration is impossible or failure, and calibration is not performed.

  A twelfth aspect of the present invention is the image forming apparatus according to any one of the first to eleventh aspects, further comprising notification means for notifying a user of a determination result relating to calibration contents.

  According to a thirteenth aspect of the present invention, in the image forming apparatus according to the eleventh aspect, the connection unit connected to the network line and the image forming unit connected to the network line when it is determined that the calibration is impossible. And a notifying means for notifying the manager of the apparatus or a service provider that performs repair / maintenance service.

  According to a fourteenth aspect of the present invention, in the image forming apparatus according to any one of the first to thirteenth aspects, an output unit that outputs a pattern misalignment evaluation pattern and a pattern with the smallest plate misalignment are determined to determine the plate misalignment. Determining means for determining the amount, wherein the calibration content determining means does not perform the second calibration when the amount of misregistration is greater than or equal to an allowable value.

  According to a fifteenth aspect of the present invention, in the image forming system in which the image forming apparatus according to any one of the fifth to fifteenth aspects is connected to a display device, the color of the reflective original and the display color of the display device are visible. Monitor calibration means for matching the first and second reference charts, wherein the first reference chart and the second reference chart are displayed on the display device.

According to the present invention, since the calibration content is determined from the result of determining whether the color variation of the image forming apparatus is due to the gamma variation or the variation of the color mixing characteristics, an appropriate calibration for the cause of the color variation is performed. Can be implemented.
Thus, even in an inexpensive image forming apparatus that cannot be provided with an expensive colorimetric device, it is possible to perform appropriate calibration according to the cause of color variation.

Also, in the image forming apparatus, when the gamma characteristic or the color mixing characteristic fluctuates significantly and it is judged that calibration cannot be performed or a failure occurs, the calibration work is omitted, and the execution items are optimized (the extra work is not necessary). Not).
Further, since the determination result relating to the calibration content is notified to the user, the administrator of the image forming apparatus, or the service provider performing the repair / maintenance service, the user can quickly take an appropriate response. .

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

<Embodiment 1>
FIG. 1 is a block diagram illustrating a configuration of an image forming apparatus according to the present embodiment. In FIG. 1, the image forming apparatus includes an image processing apparatus 1, a display apparatus 2 for displaying an image such as a CRT or LCD, and an image output apparatus 3 for outputting an image such as a printer.
Here, the image processing device 1, the display device 2, and the image output device 3 may be applied as a system constituted by independent devices, or a device composed of a single device incorporating the functions of these devices. (For example, a copying machine or a facsimile machine) may be used.
In the following description, the image processing device 1, the display device 2, and the image output device 3 will be described as independent devices.

  In FIG. 1, an image processing apparatus 1 includes a colorimetric data holding unit 4 that stores and holds colorimetric data related to calibration, and a reference color calculation that calculates a reference color of a secondary color based on the measured primary color data. 5, a color shift amount calculation unit 6 that calculates a color shift between the reference color of the primary color stored in the storage unit 11 and the reference color of the secondary color calculated in 5 and the measured color, and a color shift amount and storage An evaluation amount calculation unit 7 for calculating an evaluation amount based on an allowable value stored in the unit 11, a calibration content determination unit 8 for determining the content of calibration to be performed, and a user for the user to operate the apparatus Interface unit 9, communication interface unit 10 for communication with display device 2 and image output device 3, storage unit 11 for storing reference colors and allowable values, and device profile for storing device profiles of image output device 3 A file 12, a gamma table 13 for storing a gamma table of the image output device 3, a profile creation / update unit 14 for creating and updating a device profile used in color management, and a gamma table for creating / updating the gamma table of the image output device 3 The creating / updating unit 15 and a control unit 16 for controlling the entire processing of the apparatus.

Hereinafter, each configuration will be described in detail.
First, an evaluation pattern as shown in FIG. 2 is output by the image forming apparatus, and the density and color value of each pattern are measured and stored in the colorimetric data holding unit 4. The calorimetric data stored in the calorimetric data holding unit 4 is used for calibration.
The evaluation pattern shown in FIG. 2 includes primary colors and secondary colors (red, green, blue (hereinafter, R) that are at least cyan, magenta, yellow, and black (hereinafter referred to as C, M, Y, and K). , G, and B))). At this time, each plate (primary color) constituting the secondary color patch in the evaluation pattern corresponds to one of the primary color patches in the evaluation pattern.

  In addition, FIG. 2 shows an example in which the brightness of each color is changed to three levels of highlight, middle, and shadow, but it is naturally not limited to this. Further, a finely divided brightness may be used as a representative color, or a secondary color as well as a tertiary color (for example, skin color) or a quaternary color (gray) may be used as a representative color. .

The reference color calculation unit 5 predicts R, G, and B reference colors of the secondary colors from the colorimetric values (for example, CIELAB values) of the primary colors stored in the colorimetry data holding unit 4.
For example, each of the R color values (Lr *, ar *, br *) is changed to the Nth order of the M and Y color values (Lm *, am *, bm *) (Ly *, ay *, by *). A prediction formula is derived in advance using a polynomial (formula (1)), and the coefficient values of each parameter are stored.
This parameter is derived using a method such as a least square method based on the result of outputting and measuring a large number of colors using an image output apparatus in a reference state.
That is, the following prediction formula coefficients p11, p12... Are obtained and stored in advance.

Parameters for predicting G and B color values are also stored in the same manner.
However, the present invention does not limit the secondary color derivation method to the above method. For example, a table that associates the relationship between the density value of the primary color and the color value of the secondary color is created and stored in advance, and the closest one is obtained by reference or reference data based on interpolation. May be.

The color misregistration amount calculation unit 6 calculates the color misregistration amount between the reference color and the measurement color as follows.
Here, the color misregistration amount calculated for the primary color represents the degree of variation in the gamma characteristic, and the color misregistration amount for the secondary color or higher color represents the variation in the color mixing characteristic. Represents the degree to which.
For the primary color, the amount of color misregistration between the reference color set for each representative color and the measured color is calculated. Each reference color is stored in the storage unit 11 as shown in FIG.
For the secondary color, the reference color calculation unit 5 calculates the amount of color misalignment between the reference color of the secondary color obtained from the measured value of the primary color and the measured color. At this time, the color misregistration amount is calculated for each color component of lightness, saturation, and hue. Let this be dL, dC, dH.
Here, when the reference color is (Lref *, aref *, bref *) and the measurement color is (Ls *, as *, bs *), dL, dC, and dH are expressed by the following equation (2).

The evaluation amount calculation unit 7 calculates an evaluation amount representing the output state of the image forming apparatus based on the color misregistration amount calculated by the color misregistration amount calculation unit 6 as follows.
For each representative color, permissible values SHL, SHC, and SHH are set in the storage unit 11 for each brightness, saturation, and hue direction (see FIG. 3), and dL, dC, and dH are set using these permissible values. Each shift amount is normalized by equation (3). The normalized color misregistration amounts are dLS, dCS, and dHS.
These allowable values SHL, SHC, and SHH are obtained in advance by subjective evaluation experiments for each representative color. Thereby, evaluation reflecting human perception characteristics can be performed. Furthermore, since normalization is performed with the tolerance set by subjective evaluation for each direction, even if the tolerance varies depending on the evaluation color, comparative evaluation can be performed.

  The evaluation amount CEV is calculated for each representative color by using the normalized color misregistration amounts dLS, dCS, and dHS according to Equation (4).

  The calibration content determination unit 8 compares the evaluation amount CEV for each representative color calculated by the evaluation amount calculation unit 7 with the allowable value SH read from the storage unit 11, and performs two determinations described below. The determination result is stored in the storage unit 11.

First, it is determined whether or not any of the evaluation values of the primary colors C, M, Y, and K has an allowable value SH or more. The determination for the primary color is referred to as determination X.
Subsequently, it is determined whether or not any of the evaluation values of the secondary colors R, G, and B has an allowable value SH or more. This determination for the secondary color will be referred to as determination Y.
These determination results are stored in the storage unit 11.

  In the following description, in the above-mentioned determination X and determination Y, the determination result when there is a value equal to or higher than SH is expressed as “T”, and when there is no determination, it is expressed as “F”. The results of determination X and determination Y are collectively expressed as (T, F). Here, (T, F) represents “determination X: T, determination Y: F”.

  In the control unit 16, the calibration is performed by switching from one of the results determined by the calibration content determining unit 8 to any one of the following four according to the combination of the result of the determination X and the determination Y.

(1) For (T, T): Gamma correction and profile update are performed. This is a case where both the color mixing characteristic and the gamma characteristic are fluctuating in the image forming apparatus, and the calibration execution items are optimized by performing both the gamma table update and the device profile update. Can be planned.

(2) For (T, F): Only gamma correction is performed. This is a case where only the gamma characteristic fluctuates in the image forming apparatus, and only the gamma table is updated, so that unnecessary device profiles need not be updated, and the calibration execution items can be optimized. Can be planned.

(3) When (F, T): Only the profile is updated. This is a case where only the color mixing characteristics fluctuate in the image forming apparatus, and it is not necessary to update the unnecessary gamma table by only updating the device profile, and optimization of calibration execution items is performed. Can be planned.

(4) (F, F): Calibration is not performed. This is a case where there is no color variation in the image forming apparatus, and it is possible to optimize the items to be calibrated by not performing the calibration work and eliminating the extra work. .

Further, before the above determination, the control unit 16 holds an allowable value SHF (> SH) indicating a failure in advance, and the evaluation amount CEV of each patch of C, M, Y, K, R, G, B is calculated. If any of them exceeds SHF, calibration is not performed and a message “Calibration is impossible or failed” is displayed on the display device 2 to notify the user. May be terminated.
As described above, in the image forming apparatus, when the gamma characteristic or the color mixing characteristic is remarkably fluctuated and it is determined that the calibration cannot be performed or the malfunction is detected, the calibration operation is omitted, and the optimization of the implementation items (extra No work is done).
If the calibration cannot be performed, the determination result may be displayed on the display device 2 to notify the user. Thereby, a user can take an appropriate response quickly.

In addition, when it is determined that the image forming apparatus is out of order, a message indicating the failure is displayed on the display device 2 and the administrator of the image forming apparatus connected to the image forming apparatus and the network or the apparatus Information indicating the status of the apparatus and an evaluation value may be notified to a department or business operator that performs repair / maintenance service.
As a result, appropriate measures such as repair can be quickly performed, and the operation stop state can be shortened.

(First calibration)
The gamma table creating / updating unit 15 corrects the gamma characteristic for the primary color and updates the gamma table 13.
That is, the primary color image data (8-bit data from 0 to 255, or halftone dot area ratio data represented by 0% to 100%) in the evaluation pattern shown in FIG. From the correspondence, adjustment is performed so that predetermined gradation characteristics (for example, density and brightness) are obtained.
For example, the gamma table is corrected or an optimum one is selected from a plurality of gamma tables prepared in advance. There are many methods for setting the gamma table, and the method described in Patent Document 2 may be used, and the specific method is not limited.

(Second calibration)
The profile creation / update unit 14 updates the device profile 12 by performing the process shown in FIG.
First, a color patch for creating a device profile is output using the image output device 3. The number of colors of the color patch to be output is not particularly limited. For example, a color patch of 729 colors, which is a combination of 9 steps of each RGB color, is output (step S401).
Next, the color patch is measured by a colorimeter (not shown) (step S402), and the measured colorimetric data is written in the data buffer (step S403).
A profile is created in a predetermined format and the device profile 12 is updated (step S404).
As a method for creating a profile from colorimetric data, for example, various methods proposed in Japanese Patent Laid-Open No. 2000-196905 can be used.

Since the first embodiment is configured as described above, the contents of calibration are determined from the result of determining whether the color variation of the image forming apparatus is due to gamma variation or color mixing property variation. Therefore, appropriate calibration can be performed for the cause of color variation.
Further, since the secondary color reference color in the reference state is predicted from the color measurement data of the primary color, it is possible to evaluate the color mixing characteristics without being affected by the gamma fluctuation.

Next, a calibration processing procedure in the image forming apparatus according to the present invention will be described with reference to the flowchart of FIG.
First, as shown in FIG. 2, the image output device outputs an evaluation pattern composed of C, M, Y, K primary colors and secondary colors (R, G, B) (step S101). Then, the density and color value of each pattern are measured (step S102), and the measurement result is stored in the colorimetric data holding unit 4 (step S103).

Next, R, G, and B reference colors of the secondary color are predicted from the measured colorimetric values (for example, CIELAB values) of the primary color (step S104).
For example, each of the R color values (Lr *, ar *, br *) is changed to the Nth order of the M and Y color values (Lm *, am *, bm *) (Ly *, ay *, by *). A prediction formula is derived in advance using a polynomial (formula (1)), and the coefficient value of each parameter is stored. This parameter is derived using a method such as a least square method based on the result of outputting and measuring a large number of colors using the output device in the reference state.

Next, the amount of color misalignment between each reference color (see FIG. 3) stored in the storage unit 11 and the measured color stored in the colorimetric data holding unit 4 is set as lightness (dL) and saturation (dC). For each color component of hue (dH), calculation is performed using equation (2) (step S105).
For the primary color, the amount of color shift between the reference color set for each representative color and the measured color is calculated. For the secondary color, a color misregistration amount between the reference color of the secondary color obtained from the measured value of the primary color and the measured color is calculated in step S104.

Next, an evaluation amount CEV representing the output state of the image forming apparatus is calculated as follows based on the color misregistration amount (step S106).
For each representative color, the permissible values SHL, SHC, and SHH (see FIG. 3) for each lightness, saturation, and hue direction are read from the storage unit 11, and each color shift amount of dL, dC, and dH is normalized by Expression (3). To do. The normalized color misregistration amounts are dLS, dCS, and dHS.
The evaluation amount CEV for each representative color is calculated from the normalized color misregistration amounts dLS, dCS, and dHS by the equation (4).

The calculated evaluation amount CEV for each representative color is compared with the allowable value SH read from the storage unit 11, two determinations described below are performed, and the determination result is stored in the storage unit 11. (Step S107).
First, it is determined whether or not any of the evaluation values of the primary colors C, M, Y, and K is greater than the allowable value SH (referred to as determination X). Subsequently, it is determined whether or not any of the evaluation values of the secondary colors R, G, and B is greater than the allowable value SH (referred to as determination Y).
In the determination X and the determination Y, the determination result when there is a value equal to or higher than SH is expressed as T, and when there is no determination, it is expressed as F.

When both the results of determination X and determination Y are “F” (YES in step S108), the process ends.
On the other hand, when the result of determination X is “T” (YES in step S109), the first calibration is performed to correct the gamma characteristic (step S110), and the process proceeds to step S111.
When the result of determination Y is “T” (YES in step S111), the second calibration is performed to update the profile (step S112), and the process is terminated.

<Embodiment 2>
Next, a second embodiment of the image forming apparatus according to the present invention will be described. Since the configuration of the second embodiment is the same as that of the first embodiment shown in FIG. 1, only the differences will be described here.
In the second embodiment, first, the image forming apparatus outputs a primary color evaluation pattern as shown in FIG. 6 with different densities for the primary colors of C, M, Y, and K. The density of each pattern is measured and stored in the colorimetric data holding unit 4. (The smaller the number in FIG. 6, the lower the density, and the higher the number, the higher the density.)

The image forming apparatus according to the second exemplary embodiment includes a first reference chart (FIG. 7) and a second reference chart (FIG. 8).
This first reference chart (FIG. 7) is a chart showing C, M, Y, and K reference colors that the image forming apparatus reproduces in the reference state, and is composed of only primary colors. Although FIG. 7 shows the case of only one patch for each color, the present invention is not limited to this, and it goes without saying that a plurality of patches may be used.
On the other hand, the second reference chart (FIG. 8) shows colors (shaded patches in the figure) obtained when a primary color plate having the same color as the first reference chart is synthesized in the reference state of the image forming apparatus. At the center, it is composed of a plurality of patches with different colors in the brightness, saturation, and hue directions.

  The reference color calculation unit 5 determines which patch of the first reference chart is substantially equal to the density of the primary color evaluation pattern stored in the colorimetric data holding unit 4 as follows: The patch of the second reference chart whose color is closest to the secondary color patches of R, G, B is selected, and the patch number of the chart is registered.

Corresponding colors of the first reference chart and the primary color evaluation pattern of FIG. 6 are compared, and a patch of the first reference chart showing substantially the same density is selected. Numbers are assigned to the output patches, and the corresponding patch numbers are registered.
For example, assuming that the hatched patch in FIG. 6 is selected as a sample having a density substantially equal to that of the first reference chart, the number of each patch of the selected first reference chart is C: +2, M: -1, Y: 0, K: -2.

Next, secondary color evaluation patterns R, G, and B (see FIG. 9) are output by superimposing the primary colors C, M, and Y corresponding to the selected patch number.
For example, in the above example, R combines and outputs patches of M: -1 and Y: 0, and similarly, G is a patch of C: +2 and Y: 0, and B is a patch of C: +2 and M: -1. Are combined and output.

  The output R, G, B secondary color evaluation pattern and the second reference chart are compared, the patch having the closest color is selected from the second reference chart, and the patch of the second reference chart is selected. Register the number.

  The color misregistration amount calculation unit 6 holds in advance a table that measures the relationship between the combination of the patch numbers of the first and second reference charts and the color misregistration amount of the secondary color. The color misregistration amount of the secondary color is obtained from the patch numbers of the registered first and second reference charts with reference to the table.

  The evaluation amount calculation unit 7 and the calibration content determination unit 8 can be obtained in the same manner as in the first embodiment. Further, the calibration in the control unit 16 is also controlled in the same manner as in the first embodiment.

By adopting the configuration as described above, it is possible to determine whether the color variation of the image forming apparatus is due to gamma variation or color mixing characteristic variation without using a colorimetric device. Even in an inexpensive image forming apparatus that cannot be used, it is possible to perform appropriate calibration according to the cause of color variation.
In addition, since the variation of the gamma characteristic and the variation of the color mixing characteristic are independently evaluated, it is possible to perform appropriate calibration according to the cause of the color variation of the image forming apparatus.

Next, a calibration processing procedure according to the second embodiment will be described with reference to the flowchart of FIG.
First, patches with different densities are output for the primary colors C, M, Y, and K as shown in FIG. 6 (step S201).

  Corresponding colors of the first reference chart and the evaluation pattern of FIG. 6 are compared, a patch showing substantially the same density is selected, and a number corresponding to this patch is registered (step S202).

  Next, secondary color evaluation patterns R, G, and B (see FIG. 9) in which the primary colors of C, M, and Y corresponding to the selected patch number are superimposed are output (step S203).

The secondary color patches of R, G, and B output in step S203 are compared with the second reference chart, the patch with the closest color is selected from the second reference chart, and the patch number of the second reference chart Is registered (step S204).
By referring to a table in which the patch numbers and the color misregistration amounts of the first and second reference charts are measured in advance, the color misregistration amount of the secondary color is obtained (step S205).

  Hereinafter, steps S206 to S212 are the same as those in FIG. 5 in the first embodiment, and a description thereof will be omitted.

<Modification of Embodiment 2>
Further, as a modification of the second embodiment, not only the primary color evaluation pattern (see FIG. 6) is output and stored in the colorimetric data holding unit 4, but also a misregistration measurement pattern as shown in FIG. The measured data is output and stored in the colorimetric data holding unit 4.

  This pattern misalignment evaluation pattern is arranged so that the C, M, Y, and K lines are adjacent to each other. When there is no misalignment, the 0th C and M lines in the figure match, When the number increases to +1, +2,..., The M line shifts in the upper part of the drawing with respect to the C line, and the M line shifts in the lower part of the drawing with respect to the C line as −1, −2 It is configured to indicate the state. The same applies to other colors.

The pattern for evaluating misregistration output from the image forming apparatus is determined, the number of the line with the least misregistration is obtained, the line number and the misregistration amount are stored in advance as a table, and the line number for which this table is obtained The amount of misregistration is obtained by referring to.
These line numbers and plate misregistration amounts are stored in the colorimetric data holding unit 4.

The control unit 16 performs control so that the second calibration is not performed when the plate shift amount stored in the colorimetric data holding unit 4 is equal to or larger than the allowable value stored in the plate shift amount table.
In this way, the size of the plate misalignment is measured. If the plate misalignment is large, the device profile 12 is not updated, and the color change due to the plate misalignment is prevented from being confused with the change in the color mixing characteristics. It is possible to avoid an erroneous determination in the contents of calibration.

  The measurement of the plate misalignment is not limited to the method using the evaluation pattern shown in FIG. 11, and it is only necessary to quantify the amount of misalignment occurring in the image forming apparatus. For example, an apparatus such as a scanner or a CCD camera is used. The pattern may be read using, and this may be analyzed to determine the amount of misregistration.

<Embodiment 3>
In the third embodiment, the image forming apparatus according to the above-described embodiment is used as an output device, and the display device 2 that displays the calibration evaluation in progress is matched with the appearance of the color of the reflective original and the display color of the display device 2. An observation environment equipped with monitor calibration means is prepared.
Under such an observation environment, the correspondence between the color displayed on the display device 2 and the color value of the reflective original that is the same color as this display color is obtained, and in the observation environment, FIG. 7 and FIG. A corresponding reference chart is displayed on the display device 2, and a comparison determination is performed between the primary color evaluation pattern (FIG. 6) and the secondary color evaluation pattern (FIG. 9).
Next, using the correspondence relationship between the display color and the color value of the reflective original, the color value of the evaluation pattern is obtained from the determination result.
An evaluation amount may be calculated using the obtained color value, and the calibration execution determination may be performed.

  As described above, since the reference color is displayed on the display device instead of outputting the reference chart to the output device, the cost for maintaining the chart can be reduced.

1 is a block diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment. It is an example of the pattern for evaluation. It is an example of a table that holds a reference color, brightness, saturation, permissible value for each hue direction, permissible value indicating failure, and the like set for each representative color. It is a flowchart which shows the flow of a process of the profile creation / update part which updates a device profile. 3 is a flowchart illustrating a calibration processing procedure according to the first embodiment. It is an example of the pattern for primary color evaluation. It is an example of the 1st standard chart. It is an example of the 2nd standard chart. It is an output example of a secondary color evaluation pattern created by synthesizing the first reference chart corresponding to the primary color evaluation pattern. 10 is a flowchart illustrating a calibration processing procedure according to the second embodiment. It is an example of a pattern for measuring plate misalignment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image processing apparatus, 2 ... Display apparatus, 3 ... Image output apparatus, 4 ... Colorimetric data holding part, 5 ... Reference | standard color calculation part, 6 ... Color shift amount calculation part, 7 ... Evaluation amount calculation part, 8 ... Calibration Content determination unit, 9 ... user interface unit, 10 ... communication interface unit, 11 ... storage unit, 12 ... device profile, 13 ... gamma table, 14 ... profile creation / update unit, 15 ... gamma table creation / update unit, 16 ... control unit.

Claims (15)

  In a color image forming apparatus having a calibration function, for each representative color, a holding unit that holds a reference color and an allowable value reproduced by the image forming apparatus in a reference state, and the image forming apparatus corresponding to the representative color A reference color calculation means for calculating a colorimetric result of the patch outputted by the reference color and a deviation amount with respect to the reference color; an evaluation amount calculation means for obtaining an evaluation amount from the deviation amount and the allowable value; and evaluation for a plurality of the representative colors An image forming apparatus comprising calibration content determination means for determining whether or not calibration is performed and the content of calibration to be performed based on the amount.   2. The image forming apparatus according to claim 1, wherein for the representative colors other than the primary color among the representative colors, a primary color required to form the representative color is output from a color measurement result of a patch output from the image forming apparatus. An image forming apparatus that calculates a reference color.   3. The image forming apparatus according to claim 1, wherein the allowable value is a value that is set for each hue, saturation, and brightness and reflects a visual characteristic.   4. The image forming apparatus according to claim 1, wherein the evaluation amount is calculated by normalizing the deviation amount with the allowable value. 5.   In a color image forming apparatus having a calibration function, a first reference chart composed of representative colors that can be reproduced with only the primary color of the image forming apparatus, and a primary corresponding to the representative colors in the first reference chart. A second reference chart including representative colors obtained by mixing colors, and outputting a plurality of patches in which colors are struck within a predetermined range so as to include the representative colors given by the first reference chart; A patch obtained by comparing colors with the first reference chart, determining a patch that is closest in color to the first reference chart among the output patches, and mixing the determined primary color patches A reference color calculation means for comparing the output patch and the second reference chart, and determining a patch in the second reference chart having the closest color, and calculating an evaluation amount from the determination result You An evaluation value calculation means, based on the evaluation value, the image forming apparatus characterized by having a calibration content determining means determines the presence and implementation to calibrate the contents of the calibration performed.   6. The image forming apparatus according to claim 1, wherein the calibration content determination unit calculates the allowable value for each of an evaluation amount for a representative color of a primary color and an evaluation amount for a representative color other than the primary color. A comparison is performed, and it is determined whether to execute the first calibration for updating the gamma characteristic based on the comparison result or the second calibration for updating the device profile information of the image forming apparatus. An image forming apparatus.   7. The image forming apparatus according to claim 6, wherein the calibration content determination unit has an evaluation amount for a representative color of a primary color within an allowable range, and an evaluation amount for a representative color other than the primary color is out of the allowable range. In some cases, the second calibration is performed.   7. The image forming apparatus according to claim 6, wherein the calibration content determination unit has an evaluation amount for a representative color of a primary color outside an allowable range, and an evaluation amount for a representative color other than the primary color is within an allowable range. In some cases, an image forming apparatus that performs the first calibration.   The image forming apparatus according to claim 6, wherein the calibration content determination unit determines that the evaluation amount for the representative color of the primary color and the evaluation amount for the representative color other than the primary color are outside the allowable range. An image forming apparatus that performs the second calibration after performing the first calibration.   7. The image forming apparatus according to claim 6, wherein the calibration content determination unit performs calibration when the evaluation amount for the representative color of the primary color and the evaluation amount for the representative color other than the primary color are both within an allowable range. The image forming apparatus is characterized in that no application is performed.   The image forming apparatus according to claim 6, wherein the calibration content determination unit is configured such that when the evaluation amount for the primary color or the secondary color is outside a second allowable range different from the allowable range. Is an image forming apparatus characterized in that it is determined that calibration is impossible or a failure and calibration is not performed.   12. The image forming apparatus according to claim 1, further comprising a notifying unit for notifying a user of a determination result related to calibration contents.   12. The image forming apparatus according to claim 11, wherein if it is determined that calibration is impossible, an administrator of the image forming apparatus connected to the network line or a repair / maintenance service. An image forming apparatus comprising: notification means for notifying a service provider that implements   14. The image forming apparatus according to claim 1, further comprising: an output unit that outputs a pattern misalignment evaluation pattern; and a determination unit that determines a pattern misalignment amount by determining a pattern having the smallest plate misalignment. In the image forming apparatus, the calibration content determination unit does not perform the second calibration when the plate displacement amount is equal to or larger than an allowable value.   16. An image forming system in which the image forming apparatus according to claim 5 and a display device are connected to each other, monitor calibration means for matching the appearance of the color of the reflection original and the display color of the display device. And an image forming system, wherein the first reference chart and the second reference chart are displayed on the display device.