JP2002344759A - Imaging apparatus and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a general user encountering the difficulty of detecting color fluctuations in an image, formed by the conventional image forming apparatus and correcting it. SOLUTION: An imaging apparatus where image data in a 1st color space, independently of the device are converted into image data in a 2nd color space subordinate to the device on the basis of a device profile and an image is formed on a recording medium. The imaging apparatus is provided with a color meter that can measure the chromaticity of the formed image, the imaging means forms a sample image on the recording medium (S2), the color meter automatically measures chromaticity of the sample image (S3), a correction table for applying color correction to the image data in the 2nd color space is generated, on the basis of the chromaticity (S6), and the image forming means forms an image, on the basis of the image data, after the color correction by the correction table.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus for performing tint correction based on a device profile and a control method thereof.

[0002]

2. Description of the Related Art With the spread of network technology, the number of opportunities for selecting a plurality of color printers as digital image printing destinations has increased. Accordingly, even when the same image data is output by a plurality of color printers, it is required that the same color be output with the same image quality. Therefore, with respect to the color reproducibility of a color printer, there is a need for color reproduction stability that is free from environmental changes, changes over time, and machine differences.

Therefore, the so-called device independence can be obtained for a plurality of different device output colors such as display colors, printing machine output colors, and printer output colors if the original digital image data is the same. Dent
Conventionally, in order to realize color (hereinafter, device-independent color), for each device having a unique color reproduction characteristic, such as a display, a printing machine, or a printer, a profile that defines the color output characteristic of the device is created in advance. A color management system (hereinafter, CMS) that performs a color conversion process from an input color to a device independent color based on the profile is known.

However, for example, in a color image forming apparatus such as a color laser beam printer employing an electrophotographic system, in order to form an image using static electricity, environmental conditions such as temperature and humidity, a photosensitive member and a developer are required. The color of the output image fluctuates with changes in material conditions such as deterioration with time.

To cope with such a problem, various techniques for stabilizing the basic color density of an output image in a color image forming apparatus have been proposed. For example, JP-A-1-30
Japanese Patent Application Laid-Open No. 9082 describes a technique in which a patch pattern for detecting toner density formed on a photoreceptor is read by a density sensor and fed back to a toner density control unit in a developing device to control the density to an appropriate level. Further, as a modified example thereof, a technique of forming a similar toner patch on an intermediate transfer member or a paper transport belt and measuring the density thereof is also known.

In general, a toner patch can be easily created and erased, but only density information before fixing can be obtained. Therefore, when density control is performed based on the toner patch, the influence after the fixing step is naturally affected. Not reflected. further,
When toners of a plurality of colors are superimposed, only the outermost surface layer of the unfixed toner image can be detected, so that the toner density of the secondary color or the tertiary color cannot be detected.

Accordingly, various methods have been proposed for forming a patch pattern as a fixed image on recording paper.
Since the fixed image is the final form in all the steps of image formation, there is an advantage that the formed density can be comprehensively evaluated including the density fluctuation in each step.

An image forming apparatus for controlling the density by reading the density of a fixed image patch is disclosed, for example, in JP-A-10-1.
JP-A-93689 and JP-A-2000-241242 disclose online monitoring of a density value detected by a densitometer installed downstream of a fixing device. More specifically, a density pattern is formed and fixed on recording paper, and the toner densities of the Y, M, C, and K colors are corrected based on the measured density value of the density pattern after the fixing. . By monitoring the density of the fixed image patch in this way, more accurate density control based on the final output image can be performed.

Here, an outline of the conventional density control will be described.

FIG. 7 shows the configuration of a general image forming system. According to the figure, an image forming system is configured by a computer C1 and a printer P1 connected thereto. The computer C1 has an image processing application and various device profiles in its storage unit C12, and generates a printer color space signal via a CMS (not shown).

The printer P1 has an image processing section P11 for correcting an image signal, and generates correction data based on a density value of a density measuring section (densitometer) P13 provided inside and / or outside the printer. The image signal corrected by the image processing unit P11 is passed to the image forming unit P12, and a final output on recording paper is obtained.

The flow of image data in the image forming system shown in FIG. 7 is, as shown in FIG. 8, from an application 1 in a computer C1 to an image forming unit 3 via an image processing unit 2 in a printer P1. Transmitted in the direction.

FIG. 9 is a diagram showing a detailed configuration of the image processing section 2 shown in FIG. 8 and a more detailed flow of image data. The density value of the gradation patch formed by the image forming section 3 is detected.
An example of creating a density correction table in the color correction unit 22 based on the detected density value will be described. Of course, the exposure amount of the image forming unit 3, the developing bias and the transfer bias may be corrected based on the detected density value.

As described above, in the conventional image correction processing, the density of the image formed by the image forming unit 3 is detected, and control is performed so that the detected density becomes the target density value. That is,
Density control has been performed focusing only on the printer-dependent color space.

[0015]

Generally, the color reproducibility of a color image forming apparatus is defined by a device independent color space (for example, L * a * b *) and a printer dependent color space (for example, CMYK) defined by a printer profile. Greatly depends on the relationship.

However, in the above-described conventional density control method, the density control is performed in consideration of only the printer color space as described above, and the relationship between the printer dependent color space and the device independent color space is not considered. . That is, in the conventional density control, a pattern of a basic color is often created as a gradation patch. However, the density control is performed so that the measured density value of the basic color becomes a target density. The relationship between the value and the chromaticity representing the color appearance was not considered.

Therefore, it is difficult to accurately grasp the change in the tint of the printer output and perform highly accurate correction only by the density control in which the detected density value is fed back to the image forming section as in the above-described conventional case. Was.

On the other hand, with the spread of CMS, a color image forming apparatus in recent years is capable of outputting a desired color by mounting a device profile for the apparatus before shipment. However, if the color variation due to the color image forming apparatus itself, such as aging, increases, it becomes impossible to perform ideal color conversion with the profile created at the time of shipment.

As is well known, the sensitivity to the color difference of the human eye is extremely high, and if the chromaticity difference ΔE is 3 or more, the human eye will see a different color. Therefore, it is necessary to inspect the accuracy of the profile in order to grasp the influence of the tint variation. For this purpose, a user purchases a commercially available chromaticity meter and an application and obtains several tens to several hundreds of chromaticity meters. The output image patch must be measured to determine the chromaticity difference ΔE indicating the tint variation. If the chromaticity difference ΔE is large, it is necessary to correct / recreate the profile.

However, for general users, it is necessary to determine the timing for executing the profile accuracy check.
Furthermore, it is very difficult to perform a complicated measurement operation and analysis of the measured values, appropriately execute the inspection, and actually update the profile as needed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide an image forming apparatus for automatically detecting a tint change of a formed image and appropriately automatically correcting the change, and a control method thereof. I do.

[0022]

As a method for achieving the above object, a method for controlling an image forming apparatus according to the present invention includes the following steps.

That is, color conversion means for converting image data in a first color space independent of a device into image data in a second color space dependent on the own device based on a device profile; A method of controlling an image forming apparatus, comprising: an image forming unit that forms an image on a recording medium based on image data in a color space; and a chromaticity meter that can measure chromaticity of the formed image, A sample forming step of forming a sample image based on the sample data on a recording medium, a chromaticity measuring step of automatically measuring the chromaticity of the sample image by the chromaticity meter, and a chromaticity of the sample image. And a table creation step of creating a correction table for performing color correction on the image data in the second color space based on the image data.
An image is formed based on the image data after the color correction by the correction table.

Further, the method further comprises a profile updating step of updating the device profile based on the chromaticity automatically measured by the chromaticity meter.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the drawings.

<First Embodiment> As described above, in the conventional color correction method, the output density value from the apparatus is monitored and control is performed so that the output density value becomes the target value. Could not be predicted.

Therefore, in the present invention, in order to more accurately correct the color variation of the formed image in the apparatus, a chromaticity reading means is provided in a post-fixing step of the color image forming apparatus to monitor the chromaticity of the fixed image. The chromaticity value fluctuation in the device-independent color space is used as a trigger to suppress the tint fluctuation.

The schematic configuration of the image forming system according to the present embodiment is the same as that shown in FIGS. 7 and 8 showing the above-described conventional system configuration, and a description thereof will be omitted.

FIG. 1 is a diagram showing the configuration of the image forming section 3 in the image forming apparatus of the present embodiment. When the final image data CMYK is sent to the image forming unit 3, M, C,
Image formation is performed in the order of Y and Bk. That is, based on the final image data of each color, the exposure devices 31M to 31K
By exposing the photosensitive drums 30M to 30K uniformly charged by the chargers 32M to 32K, an electrostatic latent image of each color is formed. Thereafter, the latent images of the respective colors are developed by the developing units 35M to 35K, and the transfer units 38M to 38K sequentially transfer the toners of the respective colors onto the transfer material (recording paper) in an overlapping manner. afterwards,
The transfer material is fixed by a fixing device 37 to become a permanent image. After the chromaticity value is read by a chromaticity meter 34, the transfer material is discharged outside the apparatus by a discharge roller 36.

FIG. 2 is a diagram showing a detailed configuration of the image processing unit 2 and a more detailed flow of image data for realizing the tint control in the present embodiment, and is a diagram showing the above-described conventional configuration example. 9 corresponds. In FIG. 2, the image data 11 created by the application 1 is data in an arbitrary color space, but here, image data in a device independent color space (for example, L * a * b * uniform color space) or It is assumed that image data converted into a device-independent color space is output.

In FIG. 2, the flow of data in a normal image forming process is shown by a solid line. That is, image data 1
Reference numeral 1 denotes a color conversion unit 21 that converts the data into a data format of a printer dependent color space (for example, a CMYK color space) depending on the image forming apparatus, and then converts the data into a color correction unit 22 and a gradation correction unit 23.
Are converted into an output format (binary / multi-valued) by the screen generating unit 24, and the image forming unit 3 forms an image on recording paper.

The color correction unit 22 and the gradation correction unit 23 correct image data using a correction table. These correction tables are created / updated according to the data flow indicated by the dotted line in FIG. That is, the color sample data 25 in the CMYK color space held in the storage unit 27 is sent to the image forming unit 3 via the screen generating unit 24, and a CMYK color sample image is formed. Then, the chromaticity value (L * a * b * value) of the color sample image is automatically measured by the chromaticity meter 34, and the chromaticity value is fed back to the color conversion unit 21 in the image processing unit 2 to obtain C ′.
After being converted to M'Y'K 'values, it is compared with the original sample data (CMYK values) 25,
Each correction table is created. In addition, as shown in FIG.
, And indicate the order of processing when creating a color correction table described later.

The functions executed in the image processing section 2 can be realized by a printer driver on the computer C1.

The image processing in this embodiment will be described in more detail.

The image data from the application 1 in the device independent color space (L * a * b *) is
1 and a printer dependent color space (CMYK) dependent on the device using a profile 26 and a CMS (not shown)
Is converted into image data. Here profile 26
Stores color information in a device-independent color space (L * a * b *) and image data in a printer-dependent color space (CMYK) for ideally forming a color indicated by the color information.

The color correction unit 22 performs correction using the color correction table shown in FIG. 3 on the CMYK data converted by the color conversion unit 21. Prior to the correction, the color correction table 22 performs a color generation process. , Ie, the values of all the input color components C, M, Y, R, G, B, and K shown in FIG. Specifically, for example, when only CMY data is input, C, M,
The common amount of Y is extracted as the undercolor (black component), and the remaining C,
B, R, G based on M or M, Y or C, Y
Extract the components. With this color generation processing, correction can be performed for all input color components shown in FIG. 3 with reference to only the respective correction tables. Hereinafter, the color correction processing in the color correction unit 22 will be described in detail.

FIG. 3 is a diagram showing an example of a color correction table used by the color correction section 22. With respect to the inputs of C, M, Y, R, G, B, and K generated by the above-described color generation processing, correction tables 221, 222, 223, and 2 are input.
The corrections are made by 24, 225, 226 and 227, respectively. For example, for C, M, and Y inputs, the tables 221, 222, and 223 store the L * of each data.
Correction values C ′, M ′, and Y ′ are set according to the magnitude of the component. If there is a shift in the profile used for color conversion, a secondary color may be generated as a correction value.

When correcting R, G, and B, the tables 224, 225, and 226 change the ratio of (M, Y), (C, Y), and (C, M) that form those colors. ,
(M ', Y', (C ')), (C', Y ', (M')), (C ',
M ′, (Y ′)). Further, for K input, the table 227 outputs (C ′, M ′, Y ′) by changing the ratio of (C, M, Y) forming K.

In the color correction section 22, as described above, the C, M, and Y correction values obtained from the respective correction tables for the C, M, Y, R, G, B, and K input values. To obtain a final correction value for the image data CMYK. In the present embodiment, FIG.
By accurately creating each correction table shown in
Good correction of color fluctuation (color control) is enabled.

Hereinafter, the tint control in this embodiment, that is, the process of creating a correction table will be described in detail.
FIG. 4 is a flowchart showing a color correction table creation process according to the present embodiment.
This corresponds to the process of the same number shown in FIG. Note that the tint control of the present embodiment is provided in the color image forming apparatus.
It is executed by a control unit including a CPU (not shown), a program ROM, a work RAM, and the like.

The correction table creation processing in this embodiment, that is, the start timing of the tint control can be designated by various methods. For example, the processing may be started in accordance with a user instruction from an operation unit (not shown) of the color image forming apparatus or an instruction by a command from the computer C1, or may be started at a preset timing. The preset timing may be, for example, a predetermined time, a periodic execution every predetermined period, or a time when an environmental change occurs, such as when a toner cartridge is replaced.

In the default setting, CMYK sample data for forming a color gradation sample shown in FIG.
1) The color sample data 25 is input to the screen generation unit 24 without correction, binarized or multi-valued, sent to the image forming unit 3, and formed as a fixed image on recording paper. (S2). Although the color sample data 25 is constituted by a part of the image data stored in the profile 26, it is also possible to set a value other than the already set values from the profile 26 as necessary. .

The chromaticity value (L * a * b *) of the formed sample image is automatically read by the chromaticity meter 34 without user intervention (S3). If the chromaticity value read here is not in the L * a * b * format, that is, if it is not a value in the device-independent color space set in the profile 26, it is converted to a device-independent color space. The calculated value (L * a * b *) is output.

The read chromaticity value is sent to the color conversion section 21, and the chromaticity value is converted into CMYK format data depending on the image forming apparatus using the profile 26 and a CMS (not shown) ( S4). Then, the converted CMY
K data and CMY as color sample data 25
By comparing the K data, correction data C ′, M ′, Y ′, and K ′ for correcting the difference are generated and passed to the color correction unit 22 (S5).
Is created (S6).

Next, the processing for creating a color correction table will be described in further detail, taking as an example a case where a correction table for the R color component is created.

For example, the 80% R patch shown in FIG.
M = 80, Y = 80, and C = K = 0. This R
After the patch is sent to the image forming unit 3 without correction and a fixed image is formed on the recording paper, the chromaticity value L * a * b * of the R patch is read by the chromaticity meter 34. Further, the chromaticity value L *
a * b * is sent to the color conversion unit 21 and converted into CMYK format data. As a result of the color conversion, for example, M ′ =
Assuming that 85 and Y '= 75 are obtained, by comparing this with M = 80 and Y = 80 in the original R patch, correction data (M = -5, Y = + 5) is obtained. The correction data is set in the R color correction table as a correction value for the 80% R patch.

As in the case of the 80% R patch described above, a correction table can be created for all the color patches shown in FIG. For colors other than the color patches shown in FIG. 5 (for example, 85% R), a correction table is created by linear / curve interpolation or the like by default.

Further, the closest image data stored in the profile 26 is designated by the user, and a correction table is created or the interpolation accuracy is increased as in the case of the 80% R patch described above. Can be.

As described above, according to the present embodiment,
Color variations are easily and accurately detected automatically and a color correction table is automatically created so as to maintain the original color, so that the color of the formed image is always maintained with high accuracy without user intervention. .

Therefore, high color reproducibility can be obtained without the user having to individually respond to a change in color due to an environmental change of the apparatus or a replacement of the toner cartridge.

<Second Embodiment> Hereinafter, a second embodiment according to the present invention will be described.
An embodiment will be described.

In the above-described first embodiment, an example has been described in which the input image data is corrected by the color correction unit 22 to achieve high color reproducibility.

However, in order to realize high color reproducibility only by such correction, it is assumed that the profile of the color image forming apparatus has high accuracy.

As described above, the conventional profile creation and / or update process has been performed by outputting a sample image and using a separately prepared chromaticity meter and profile creation program. This method requires a great deal of time and labor, and therefore places a heavy burden on the user.

Therefore, in the second embodiment, in addition to the correction table creation processing in the first embodiment described above,
It is characterized in that the profile is automatically updated.

Hereinafter, the tint control in the second embodiment will be described in detail with reference to FIG. 2 and FIG. FIG.
FIG. 7 is a flowchart showing a tint control in the second embodiment, that is, a process of creating a color correction table and updating a profile, and FIGS.
Corresponds to the processing of the same number. Note that the same processes as those in FIG. 4 shown in the first embodiment are denoted by the same step numbers, and detailed descriptions thereof will be omitted. Note that, similarly to the first embodiment, the tint control of the second embodiment is also executed by a control unit (not shown) in the apparatus.

In the image forming apparatus shown in FIG. 2, color sample data 2 of CMYK values stored in the storage unit 27
5 to form a sample image on recording paper (S
1, S2), and the chromaticity value (L * a * b *) is read by the chromaticity meter 34 (S3). After the chromaticity value is color-converted by the color conversion unit 21 (S4), the original color sample data 25
By comparing with the correction data C ′, M ′, Y ′,
K ′ is generated (S5), and a correction table in the color correction unit 22 is generated (S6).

The processing up to this point is the same as that of the first embodiment.

Next, for the color sample data 25,
After performing correction using the correction table in the color correction unit 22 and the gradation correction unit 23 (S7), a sample image based on the corrected color sample data 25 is formed on recording paper and output (S8). . Then, the chromaticity value is read by the chromaticity meter 34 (S9), and the obtained chromaticity value is
After the color conversion again (S10), by comparing with the original color sample data 25 before correction,
Correction data C ", M", Y ",
K "is generated (S11).

The correction data C ", M", Y ",
It is determined whether the profile 26 should be updated based on K ″ (S12). For example, the correction data C ″, M ″,
If Y ″, K ″ is larger than the correction data C ′, M ′, Y ′, K ′ already stored in the correction table, the profile 26 is updated (S13). That is, since the color sample data 25 is constituted by the image data stored in the profile 26, the newly calculated correction data C ", M", Y ", K" are already stored in the correction table. The stored correction data C ′,
The fact that it is larger than M ′, Y ′, K ′ means that the chromaticity of the sample image formed by the image forming unit 3 and the profile 26
Means that the difference from the chromaticity information defined by becomes larger than before the correction, and
Since the accuracy of has been considerably reduced, it is determined that it should be updated.

On the other hand, the correction data C ", M", Y ", K"
Is larger than the correction data C ′, M ′, Y ′, K ′ already stored in the correction table, the tint variation is in a range that can be sufficiently dealt with only by updating the color correction table. The profile 26 is not updated.

Hereinafter, the updating process of the profile 26 will be specifically described.

In the case where an 80% R patch is taken as an example, step S
5 is M ′ = − 5, Y ′ = + 5, and the correction data generated in step S11 is M ″ =
In this case, since the correction data generated again is larger than the correction data already stored in the correction table, the profile 26 is updated in step S12.

Specifically, 80% of the R patches have M = 8
0, Y = 80, and C = K = 0, taking into account that the correction data is M ″ = − 5, Y ″ = + 10,
Of the image data stored in the original profile 26, image data in the range of M = 75 to 85 and Y = 70 to 90 is newly set as color sample data 25. Then, a sample image based on the new color sample data 25 is formed by the image forming unit 3, and the chromaticity value is read by the chromaticity meter 34. This chromaticity value is newly stored in the profile 26 as color information corresponding to the color sample data 25, so that the profile 2
6 is performed.

As described above, according to the second embodiment, since the device profile is automatically updated in addition to the automatic creation of the color correction table in the first embodiment, more accurate color reproduction is possible.

<Modification> In the above-described second embodiment, an example has been described in which the correction effect is diagnosed by creating a correction table in the color correction section 22 and then performing sample output and chromaticity measurement again. This can be simplified.

That is, when creating the correction table in the color correction section 22, the correction data C ', M', Y ', K' generated in step S5 are directly diagnosed, and the profile 26 is determined based on the diagnosis result. Can be updated.

For example, taking the case of an R patch as an example, as the correction data for the patch, in addition to the M ′ and Y ′ components, the C ′ component is obtained as a value larger than a predetermined value (0 or a minute value). Or the values of M ′ and Y ′ are relatively large,
It is desirable to recreate a part or all including the patch.

More specifically, the above 80%
, The correction data is M ′ = − 5, Y ′ = +
If it is obtained as 15, it is diagnosed that "the correction value for the Y component is too large". Then, based on the diagnosis result, the profile 26 is updated as described above,
The correction value of Y can be reduced.

Also, when the correction data for the 80% R patch is obtained as M '=-5, Y' = + 5, C '= + 5, that is, when the correction value of the C component is obtained, By updating the profile 26, the correction value of C can be eliminated.

As described above, the correction data C ′, M ′, Y ′,
By diagnosing the profile accuracy based on K ′, when the profile update is unnecessary, it is not necessary to perform processing such as formation of a new sample image and chromaticity measurement in steps S7 to S11 in FIG.

In the second embodiment, an image sample including a large number of color patches is formed based on the image data and the color sample data 25 stored in the profile 26, and the chromaticity meter 34 forms the color samples. By reading the chromaticity value and calculating the difference from the chromaticity value stored in the profile 26, the accuracy of the profile 26 can be confirmed.

[0073]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

Further, an object of the present invention is to supply a storage medium (or a recording medium) recording software program codes for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (a computer) of the system or the apparatus. It is needless to say that the present invention can also be achieved by a CPU or an MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. Also,
When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also the operating system (OS) running on the computer based on the instructions of the program code.
It goes without saying that a case where the functions of the above-described embodiments are implemented by performing some or all of the actual processing, and the processing performs the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, the program code is read based on the instruction of the program code. Needless to say, the CPU included in the function expansion card or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0076]

As described above, according to the present invention, it is possible to automatically detect a tint change of a formed image in an image forming apparatus and to appropriately automatically correct the change.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an image forming unit according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a detailed configuration of an image processing unit and a flow of image data according to the embodiment.

FIG. 3 is a diagram illustrating an example of a color correction table according to the embodiment.

FIG. 4 is a flowchart illustrating a tint control according to the embodiment.

FIG. 5 is a diagram illustrating an example of a color patch formed in the embodiment.

FIG. 6 is a flowchart illustrating a tint control according to the second embodiment.

FIG. 7 is a block diagram illustrating a schematic configuration of a general color image forming system.

FIG. 8 is a diagram showing a flow of image data in the system of FIG. 7;

FIG. 9 is a diagram illustrating a detailed configuration of an image processing unit and a flow of image data in a conventional device.

[Explanation of symbols]

 Reference Signs List 1 application 2 image processing unit 3 image forming unit 21 color conversion unit 22 color correction unit 23 gradation correction unit 24 screen generation unit 25 color sample data 26 profile 27 storage unit 34 chromaticity meter

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C262 AA24 AB11 AC07 BA01 BA15 BC19 EA04 EA12 FA13 GA01 5B057 AA11 BA02 BA11 CE17 CE18 CH07 CH18 5C077 LL01 MM27 MP08 PP33 PP36 PP37 PP38 PQ23 SS02 SS10 TT06 5C079 HB03 KA08 MA04 MA10 NA03 NA18 PA02

Claims (18)

[Claims] A color conversion unit configured to convert image data in a first color space independent of a device into image data in a second color space dependent on the own device based on a device profile; A method for controlling an image forming apparatus, comprising: an image forming unit that forms an image on a recording medium based on image data in a color space; and a chromaticity meter that can measure the chromaticity of the formed image, A sample forming step of forming a sample image based on the sample data on a recording medium by a forming unit; a chromaticity measuring step of automatically measuring the chromaticity of the sample image by the chromaticity meter; And a table creation step of creating a correction table for performing color correction on the image data in the second color space based on the image data in the second color space. Method of controlling an image forming apparatus and forming an image based on the corrected image data. 2. In the chromaticity measuring step, the chromaticity of the sample image is automatically measured as data on the first color space by the chromaticity meter. 2. The image forming apparatus according to claim 1, wherein correction data to be stored in the color correction table is created based on a value obtained by converting chromaticity into image data in the second color space by the color conversion unit. How to control the device. 3. The method according to claim 1, wherein the sample data includes a part of image data constituting the device profile. 4. The method according to claim 1, further comprising a profile updating step of updating the device profile based on the chromaticity automatically measured by the chromaticity meter. 5. The profile updating step includes: a sample data correcting step of correcting the sample data based on the correction table to generate second sample data; A second sample forming step of forming a second sample image on a recording medium based on the second sample image; a second chromaticity measuring step of measuring the chromaticity of the second sample image with the chromaticity meter; 5. The method according to claim 4, further comprising an updating step of updating the device profile based on the control information. 6. In the updating step, a second correction table for the correction table is set based on a chromaticity of the second sample image.
6. The method according to claim 5, wherein the correction data is created, and the device profile is updated based on the second correction data. 7. The device according to claim 6, wherein, in the updating step, the device profile is updated when the second correction data is larger than correction data already stored in the color correction table. The control method of the image forming apparatus described in the above. 8. The method according to claim 6, wherein in the updating step, the device profile is updated when the second correction data is equal to or more than a predetermined value. 9. The device according to claim 6, wherein, in the updating step, when the second correction data has a color component value other than a predetermined value, the device profile is updated.
The control method of the image forming apparatus described in the above. 10. In the updating step, among the image data stored in the device profile, data within a range indicated by the second correction data is set as new sample data, and based on the sample data. 7. The method according to claim 6, wherein the device profile is updated based on a chromaticity of a formed image. 11. The device according to claim 4, wherein in the profile updating step, the device profile is updated based on correction data of the correction table created based on chromaticity of the sample image. A method for controlling an image forming apparatus. 12. The method according to claim 11, wherein in the profile updating step, the device profile is updated when the correction data is equal to or more than a predetermined value. 13. The method according to claim 11, wherein in the profile updating step, the device profile is updated when the correction data has a color component value other than a predetermined value. 14. In the profile updating step, among image data stored in the device profile, data within a range indicated by the correction data is set as new sample data, and a formed image based on the sample data is generated. 12. The method according to claim 11, wherein the device profile is updated based on the chromaticity of the image. 15. A color conversion means for converting image data in a first color space independent of a device into image data in a second color space dependent on the own device based on a device profile; An image forming apparatus having image forming means for forming an image on a recording medium based on image data on a color space of the second color space, wherein the image data on the second color space converted by the color converting means is color-coded. A color correction unit that corrects based on a correction table, a chromaticity measurement unit that automatically measures the chromaticity of the sample image formed on the recording medium by the image forming unit, and a chromaticity measurement unit that measures the chromaticity. Control means for updating the color correction table based on the chromaticity of the sample image,
An image forming apparatus comprising: 16. The image forming apparatus according to claim 15, wherein the control unit updates the device profile based on the chromaticity automatically measured by the chromaticity measuring unit. 17. A program for realizing a control method of an image forming apparatus according to claim 1, which is executed by a computer. 18. A recording medium on which the program according to claim 17 is recorded.