JP2001026170A - Image processing apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent evils caused by inadaptability of a patch pattern to be used to a printer when the calibration of a printer is to be performed. SOLUTION: In an image processing system having a host computer 101 and a color printer 107, a judgment 208 of an image forming means related to the output density characteristics of the color printer 107 is preliminarily performed before the calibration of the color printer 107 is performed. That is, the same pattern as the patch pattern used in calibration is outputted by the color printer 107 and, on the basis of the read result of the pattern by a scanner 126, for example, the color printer 107 is found to have a originally bad reproduction at a low density part is and a patch pattern relatively rough in the interval between the gradation values of patches is used in the subsequent calibration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus and an image processing method, and more particularly, to calibration for making output characteristics of an image forming apparatus based on hard copy technology constant.

[0002]

2. Description of the Related Art In recent years, printers and the like, which are peripheral devices of personal computers, have become widespread, and it has become possible to easily output hard copies of word processing documents, graphic images, and the like created on computers.

FIG. 1 shows a typical configuration of such an image processing system. In this system, a host computer 101
A page layout document such as P, a word processor, a graphic document, or the like is created, and these are output as a hard copy by, for example, an electrophotographic or inkjet color printer 107 using a laser beam. The application 102 in the host computer 101 operates on the host computer, and typical examples include word processing software such as Microsoft Word and page layout software such as Adobe PageMaker®. be able to. A digital document created by such software is transferred to a printer driver 103 via an operating system (OS) of a computer 101 (not shown). A digital document is usually represented as a set of command data representing figures, characters, and the like constituting one page, and these commands are sent to the printer driver 103. These series of commands are, for example, PDL
It is expressed as a language system called (page description language), and typical examples of PDL include GDI and PS (postscript). The printer driver 103 transfers the transmitted PDL command to the rasterizer 105 in the raster image processor 104. The rasterizer 105 develops characters, graphics, and the like represented by PDL commands into a two-dimensional bitmap image that is actually output by the printer 107. That is, the bitmap image is developed as an image in which a one-dimensional raster (line) is repeatedly filled in a two-dimensional plane. The developed bitmap image is temporarily stored in the image memory 106.

FIG. 2 is a diagram schematically showing the above processing. The document image 111 displayed on the host computer 101 is sent as a PDL command sequence 112 to the rasterizer 105 via the printer driver 103, and the rasterizer 105 outputs the two-dimensional bitmap image 1
13 is developed on the image memory 106. The bitmap image data is stored in the color printer 107.
Sent to The color printer 107 can use an image forming unit 108 of a well-known electrophotographic system, an inkjet printing system, or the like. This unit forms a visible image on paper and performs print output. At the time of this print output, the image data stored in the image memory 106 is synchronized with a synchronization signal or clock signal (not shown) necessary for operating the image forming unit, a transfer request of a specific color component signal, or the like. Transferred.

By the way, in the image forming unit of the color printer in the image processing system described above, a change in output characteristics and a variation in these characteristic changes among devices occur, whereby a constant quality output image can be obtained. It is known that there may not be. For example, it is known that even when the same document is output, the color tone is different each time it is output, or different print results are obtained when output is performed by different printers.

For example, when an electrophotographic system is used as an image forming unit, laser exposure in an electrophotographic process, formation of a latent image on a photoreceptor, toner development, transfer of toner to a paper medium, fixing by heat. Such a process is caused by a change in the amount of toner that is finally fixed on paper due to the influence of the temperature and humidity around the apparatus or the aging of the components. It is known that such instability of the print output characteristic is not peculiar to the electrophotographic system, but similarly occurs in various systems such as an ink jet system, a thermal transfer system, and the like.

On the other hand, conventionally, a calibration process as shown in FIG. 3 has been proposed. This is to output a predetermined test pattern image 121 by the printer 107, measure the density of the output pattern, and correct the characteristics of the image forming unit based on the result. This calibration will be further described with reference to FIGS. 3 and 4 as follows. The reading control 202, the pattern instruction 204, the output control 206, and the gradation correction 207 of the host computer 101 shown in FIG.
3. The main part is software executed as the raster image processor 104 or the like (see FIG. 1).

First, when a start of calibration is instructed in the host computer 101, a main calibration screen is displayed on the display unit. Here, in order to perform patch output for tone correction, click on tone correction patch output. With this click, a printer driver starts up, and it becomes possible to specify a printer to be printed (a printer to be calibrated) and to specify the number of prints via the interface screen. After these designations, the host computer 101 sends a command for outputting a predetermined gradation pattern to the raster image processor 104 via the pattern instruction 204 by a click to instruct printing. The raster image processor 104 generates a bitmap pattern to be output to the printer 107 based on the command sent via the output control 206, and transfers it to the printer 107. The printer 107
The given gradation pattern 121 is printed out on a paper medium. As shown in FIG. 3, the pattern 121 output here is the toner adhesion for cyan (C), magenta (M), yellow (Y), and black (K) corresponding to each of the four color toners used in the printer 107. The pattern is such that the area ratio changes in eight steps from 0% to 100%. That is, the patches corresponding to the numbers from 0 to 7 assigned to each of the eight area ratios are C, M, Y, K
Are printed as columns 122, 123, 124 and 125. Next, C of the host computer 101
The PU 203 instructs the scanner 126 to read the gradation correction patch printed out by the reading control 202 as described above. 4 in the output pattern
There are a total of 32 rectangular patches with 8 colors ×
The scanner 126 reads each of them. Note that a simple reading device called a so-called flat head scanner can be used as the scanner. R, G, and B luminance data obtained by reading are C, M,
By converting the density values into Y and K density values and comparing them with reference values stored in advance, a correction table for each color of C, M, Y and K is created. This table is
The color printer 107 is registered in the table conversion unit used in the gradation correction 207 of the raster image processor 104, and this means that the color printer 107 has been calibrated. This table conversion unit, after calibration,
Used when generating bitmap image data to be used in a printer. That is, the table conversion unit is a gamma correction table for correcting the density value for each color written as bitmap data when the raster image processor 104 generates a bitmap image. For example, if the density of the third patch in column 121 for cyan in the pattern is measured below the reference value,
By creating a γ correction table for correcting the bitmap data corresponding to the third patch of cyan to a high value,
Thereafter, the output density characteristic of the printer can be made closer to the reference value.

[0009]

However, in the above-described conventional calibration processing, the same patch pattern is always output regardless of the type of the printer or the like to be calibrated, and correction is performed based on the read result. Create a table. For this reason, the number of patches of the output pattern, for example, may not always be suitable for the gradation range reproducible by the printer, so that it takes more time than necessary to read the pattern, or conversely, In some cases, the number of patches for measuring the density is insufficient and the correction is insufficient.

That is, some printers, for example, can hardly reproduce, for example, a low-density portion depending on the type of the printer. When such a printer or the like is calibrated, the low-density portion also has a relatively fine density step. Even if a patch is output, these read results will hardly be reflected in the subsequent print output. Conversely, if a pattern with a small number of patches in the low-density range is used for calibration of a printer or the like with good reproducibility of the low-density part, finer correction data cannot be obtained, and subsequent print output May be insufficiently corrected. Such a difference in reproducibility depending on the model is mainly caused by a difference between a printing method used by a printer, that is, an ink jet method and an electrophotographic method.

In addition to the reproduction density range, for example, in a printer or the like having a characteristic in which the deviation of the actual output density from the input density value inherently increases, the correction data is obtained based on the result of reading the patch in fine density steps. Even if it is created, the amount of correction due to it is not so different from that based on patches at the rough density stage, so calibration using a pattern with a smaller number of patches can reduce the time required for that. it can.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to use a patch pattern suitable for an image forming apparatus to be calibrated, thereby enabling an image forming apparatus. It is an object of the present invention to provide an image processing apparatus and an image processing method capable of preventing an adverse effect caused by a mismatch between a patch pattern and a patch pattern.

[0013]

According to the present invention, there is provided:
An image processing apparatus that controls an image forming apparatus to output an image to the image forming apparatus, a determination unit that determines the image forming apparatus that performs the image output, and a calibration of the image forming apparatus that performs the image output A patch pattern corresponding to the image forming apparatus determined by the determining means is output to the determined image forming apparatus,
And a calibration means for performing calibration based on the output patch pattern.

Preferably, the image forming apparatus further comprises an image forming apparatus judging means for judging an image forming apparatus for outputting an image with respect to the image output characteristics, wherein the judging means judges whether the image forming apparatus is an image forming apparatus based on a judgment result of the image forming apparatus judging means. It is characterized in that the forming apparatus is determined.

According to another aspect, there is provided an image processing apparatus for controlling an image forming apparatus to output an image to the image forming apparatus, and determining means for determining a color reproduction capability of the image forming apparatus for outputting an image. Determining means for determining the type of test pattern to be used for calibration based on a result of the determination by the determining means.

In still another embodiment, there is provided an image processing method for controlling an image forming apparatus to output an image to the image forming apparatus. A step of performing calibration of the image forming apparatus, in which a patch pattern corresponding to the image forming apparatus determined by the determination unit is output to the determined image forming apparatus, and calibration is performed based on the output patch pattern. It is characterized by having steps.

Preferably, the image forming apparatus further includes an image forming apparatus judging step of judging an image forming apparatus for performing image output with respect to the image output characteristics, wherein the judging step is performed based on the judgment result of the image forming apparatus judging step. The image forming apparatus is distinguished.

According to another aspect, there is provided an image processing method for controlling an image forming apparatus to output an image to the image forming apparatus, wherein the color reproduction capability of the image forming apparatus for outputting an image is determined. Determining the type of test pattern to be used for calibration based on the result of the determination.

According to the above configuration, when performing calibration of the image forming apparatus, the image forming apparatus is determined based on the output characteristics, and a patch pattern corresponding to the determination is used. In the calibration of the image forming apparatus in which the reproducibility of the low-density portion is not so good, a patch pattern of a rough gradation step can be used particularly for the low-density portion, thereby saving time required for reading a patch and the like. be able to. vice versa,
In the calibration of the image forming apparatus having relatively good reproducibility, a sufficient calibration suitable for the good reproducibility can be performed by using a patch pattern whose gradation is fine.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

<First Embodiment> FIG. 5 is a block diagram showing the configuration of an image processing system according to one embodiment of the present invention. Elements similar to those shown in FIG. The detailed description is omitted.

As shown in FIG. 5, the image processing system of this embodiment is different from the conventional system shown in FIG. 4 in that it is necessary to determine what output density characteristics the printer 107 has. The point is that the forming means is determined, and the patch pattern used in the calibration is determined according to the result of the determination. Hereinafter, the process of determining the color reproduction capability of the image forming unit and selecting the type of the patch pattern based on the determination result performed by the image forming unit determining unit 208 will be described.

First, an image forming means determination screen as shown in FIG. 6 is displayed on the monitor of the host computer 101. When the output of the image forming unit determination patch is clicked on the display screen as the process of step S31, the pattern instruction 204 instructs the output control 206 of the patch pattern for image forming unit determination shown in FIG.
In accordance with the instruction, the output control 206 controls the printer 107 to be determined and outputs the patch pattern. The patch pattern shown in FIG. 7 has patches corresponding to 16 levels of gradation values for each of C, M, Y, and K, and has patches with relatively fine gradation value intervals. That is, it is a patch pattern for measuring the output characteristics of the image forming means with high accuracy.

Next, when the judgment patch reading is clicked as the processing of step S32, the above-mentioned output patch pattern is read by the scanner 126. Then, the brightness data of each patch in the read data is converted into density data, and the measured density is compared with the tone value (target density) corresponding to each patch.

FIGS. 9 and 10 are schematic diagrams showing two examples of the comparison result. FIG. 9 shows a case where a printer having good reproducibility up to a low density portion is output, while FIG.
This figure shows a case where the output is performed by a printer having poor reproducibility of the low density portion. That is, in this processing, based on the comparison result, it is determined that the printer that can obtain the comparison result shown in FIG. 9 is a printer that can reproduce even a low density portion, and the calibration uses the patch pattern shown in FIG. Register (step S33). On the other hand, for a printer that can obtain a comparison result as shown in FIG. 10, a pattern with relatively large tone value intervals between patches shown in FIG. 8 is registered as a patch pattern used in the calibration. (Step S33).

That is, when judging the color reproducibility of the image forming means based on the reproducibility of the low-density portion as in the present embodiment, for example, a standard for a plurality of patches in a predetermined low-density portion region is used. When the total value of the differences from the values is larger than a predetermined value, registration is performed so as to use a pattern in which the tone value interval of the patch is relatively large.

As described above, even if the calibration is performed using the patch pattern as shown in FIG. 7 in the image forming apparatus having the results shown in FIG. 10, the reproduction of the low density portion by the apparatus is not so good. Therefore, the reading of the patches of the low density portion in the pattern and the subsequent processing are wasted. Therefore, in such an image forming apparatus, a patch pattern as shown in FIG. 8 is used in the calibration, whereby unnecessary reading processing and subsequent processing can be eliminated in advance. Also, for an image forming apparatus that shows the result as shown in FIG. 9, by using a patch pattern with a fine gradation as shown in FIG. 7, it becomes possible to perform appropriate calibration for the apparatus.

In step S33 in FIG. 6, an operation for registering the patch pattern determined as described above in association with the image forming apparatus is performed.

As described above, according to the present embodiment, it is possible to select a patch pattern that matches the output density characteristics of an image forming apparatus such as a printer used in an image processing system, thereby making it unnecessary for patch reading and associated processing. An appropriate calibration can always be performed without spending a lot of time.

In the above description, the performance of the image forming apparatus is evaluated based on the reproducibility of the low density portion.
The reproducibility of other density areas such as medium density and high density areas may be used as a reference.

The capability may be evaluated based on the reproducibility of the entire gradation. In this case, by examining the amount of deviation between the target density and the measured density, for example, the variance, for all the gradations, the image forming apparatus having a large variance may select a patch pattern with a larger gradation value.

When the calibration is performed, the color printer 107 forms a test pattern based on the determination result of the image forming unit determining unit 208 described above.
At this time, the pattern instructing unit 204 confirms the contents registered by the image forming unit determining unit 208 and instructs the output control 206 to form a test pattern according to the registered contents. Then, the formed test pattern is scanned by the scanner 1.
The CPU 203 creates a gamma correction table for each color set by the CPU 203 in the gradation correction means 207 based on the density data read in step 26 and the target value corresponding to the test pattern.

In the above description, the method of automatic determination by the image forming means determination processing has been described. However, the user of the image forming apparatus selects, for example, one of the patch patterns shown in FIG. 7 or FIG. You may make it register. At this time, so that the user can easily determine,
The measurement results as shown in FIGS. 9 and 10 may be displayed.

The image forming means judgment 208 shown in FIG.
In addition to the determination processing described above, when actually performing calibration, the type of the connected printer is determined, and a patch pattern corresponding to the determined printer is selected from a plurality of patch patterns. Reading processing can also be performed.

<Second Embodiment> In the first embodiment described above, an image processing system using one image forming apparatus has been described. In this embodiment, however, a plurality of image forming apparatuses are connected via a network. A case where the present invention is applied to such a system will be described.

FIG. 11 is a block diagram showing the configuration of the image processing system according to this embodiment. Elements of the first embodiment that are the same as the elements shown in FIG.

In this embodiment, the color printer 107A
The image forming unit determination process described in the first embodiment is performed for each of the image forming units 107B and 107B. That is, the CPU 20
3 starts this processing according to the image forming means judgment 208, whereby the processing screen shown in FIG. 6 is displayed. Then, when the output of the image forming unit determination patch pattern in step S31 is instructed, the determination pattern shown in FIG. 7 is output as described in the first embodiment. In this embodiment, at this time, an interface screen by the printer driver 103 shown in FIG.
It is possible to output the determination patch pattern, that is, select a printer to be determined from the printer 107A or the printer 107B.

Then, a patch pattern for determination is output by the selected printer, and based on the read result,
The output density characteristic of the printer is determined in the same manner as in the first embodiment (step S32), and for example, one of the patch patterns shown in FIG. 7 or FIG. 8 is registered as a patch pattern used for calibration based on the determination result (step S32). Step S33).

The above processing is performed for all printers connected to the network 211 (in this embodiment, the printer 107
A and 107B) are performed in advance, and the respective patch patterns are registered corresponding to the printer. When performing the calibration, a patch pattern is output. For example, by specifying a printer on an interface screen by a printer driver shown in FIG. 12, the patch patterns registered at the same time by this specification are read and output. can do.

As described above, according to the present embodiment, it is possible to perform calibration using an optimum patch pattern for each of a plurality of image forming apparatuses such as a printer connected via a network, and to perform calibration. In other words, it is possible to prevent a problem caused by inconsistency between the image forming apparatus and the patch pattern, such as spending more time than necessary on the processing of the application, or conversely, insufficient number of patches and insufficient calibration. .

In the above-described embodiment, the image forming apparatus is assumed to use color materials of four colors C, M, Y, and K. However, this is also applicable to other configurations, for example, three colors of C, M, and Y. It is needless to say that the present invention can be similarly applied to black or a single color, and the image forming apparatus is not limited to a printer, but includes any hard copy apparatus such as a copying machine.

<Other Embodiments> The present invention, as described above,
The present invention may be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, and the like) or may be applied to an apparatus including one device (for example, a copying machine and a facsimile machine).

Further, for realizing the functions of the above-described embodiments, a device connected to the various devices or a computer in a system so as to operate the various devices so as to realize the functions of the above-described embodiments may be implemented by, for example, FIG.
The program implemented by supplying the program code of the software described with reference to FIGS. 6 and 11 and operating the various devices according to the stored program in the computer (CPU or MPU) of the system or the apparatus is also implemented in the present invention. Included in the scope of the invention.

In this case, the program code of the software implements the functions of the above-described embodiment, and the program code itself and means for supplying the program code to the computer, such as the program code, are used. The stored storage medium constitutes the present invention.

As a storage medium for storing such a program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, magnetic tape, nonvolatile memory card, ROM or the like can be used.

When the computer executes the supplied program code, not only the functions of the above-described embodiment are realized, but also the OS (operating system) running on the computer, or another program. Needless to say, the program code is included in the embodiment of the present invention even when the functions of the above-described embodiment are realized in cooperation with application software or the like.

Further, the supplied program code is stored in a memory provided in a function expansion board of a computer or a function expansion unit connected to the computer, and then stored in the function expansion board or the function expansion unit based on the instruction of the program code. It is needless to say that the present invention includes a case where a provided CPU or the like performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0048]

As described above, according to the present invention,
By using a patch pattern suitable for the image forming apparatus to be calibrated, it is possible to prevent adverse effects due to mismatch between the image forming apparatus and the patch pattern.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of an image processing system.

FIG. 2 is a diagram illustrating data processing in the image processing system.

FIG. 3 is a diagram illustrating calibration in the image processing system.

FIG. 4 is a diagram illustrating processing of a host computer in a conventional image processing system.

FIG. 5 is a diagram illustrating processing of a host computer in the image processing system according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating an operation screen displayed in an image forming unit determination process in the image processing system according to the embodiment.

FIG. 7 is a diagram illustrating an example of a patch pattern used in the image forming unit determination processing and calibration.

FIG. 8 is a diagram illustrating another example of a patch pattern used in calibration.

FIG. 9 is a diagram illustrating an example of a relationship between a target density and a measured density of a patch pattern indicated by the image forming apparatus in the determination of the image forming unit.

FIG. 10 is a diagram illustrating a relationship between a target density and an actually measured density of the patch pattern shown by another image forming apparatus.

FIG. 11 is a diagram illustrating processing of a host computer in an image processing system according to another embodiment of the present invention.

FIG. 12 is a diagram schematically illustrating an interface screen by a printer driver in the image processing system according to the other embodiment.

[Explanation of symbols]

 101 Host Computer 103 Printer Driver 107, 107A, 107B Color Printer 126 Scanner 202 Reading Control 203 CPU 204 Pattern Instruction 206 Output Control 207 Gradation Correction 208 Image Forming Unit Judgment

Claims (18)

[Claims] 1. An image processing apparatus for controlling an image forming apparatus to output an image to the image forming apparatus, a determining unit for determining an image forming apparatus to output an image, and an image to output an image Means for calibrating the forming apparatus, wherein the calibration means outputs a patch pattern corresponding to the image forming apparatus determined by the determining means to the determined image forming apparatus, and executes calibration based on the output patch pattern. An image processing apparatus comprising: 2. The image forming apparatus according to claim 1, further comprising: an image forming apparatus determining unit configured to determine an image forming apparatus for performing image output with respect to the image output characteristics, wherein the determining unit performs image forming based on a determination result of the image forming apparatus determining unit. The image processing apparatus according to claim 1, wherein the apparatus is determined. 3. The image forming apparatus determining unit causes the image forming apparatus to be determined to output a patch pattern and makes a determination based on the output result.
An image processing apparatus according to claim 1. 4. The image processing apparatus according to claim 3, wherein the image output characteristic is reproducibility of a low density portion in an output patch pattern. 5. The image processing apparatus according to claim 3, wherein the image output characteristic is a variation from a target value in an output patch pattern. 6. The image processing apparatus according to claim 3, wherein the image forming apparatus determination unit performs the determination in accordance with a selection made by a user who has observed the output patch pattern. 7. The image processing apparatus according to claim 1, wherein the calibration unit holds the output patch pattern corresponding to each of the plurality of image forming apparatuses. . 8. An image processing apparatus for controlling an image forming apparatus to output an image to the image forming apparatus, comprising: a determination unit configured to determine a color reproducibility of the image forming apparatus performing an image output; Determining means for determining a type of a test pattern to be used for calibration based on a result of determination by the means. 9. An image processing method for controlling an image forming apparatus to output an image to the image forming apparatus, the image processing apparatus determining an image forming apparatus to output an image, and controlling the image forming apparatus to output the image. A step of performing a calibration, including outputting a patch pattern corresponding to the image forming apparatus determined by the determination unit to the determined image forming apparatus, and performing calibration based on the output patch pattern. An image processing method comprising: 10. An image forming apparatus for outputting an image,
10. The image forming apparatus according to claim 9, further comprising an image forming apparatus determining step of determining with respect to the image output characteristic, wherein the determining step determines the image forming apparatus based on a determination result of the image forming apparatus determining step. The image processing method described in the above. 11. The image processing method according to claim 10, wherein in the image forming apparatus determining step, the image forming apparatus to be determined outputs a patch pattern, and the determination is performed based on the output result. . 12. The image processing method according to claim 11, wherein the image output characteristic is reproducibility of a low density portion in an output patch pattern. 13. The image processing method according to claim 11, wherein the image output characteristic is a variation from a target value in an output patch pattern. 14. The image processing method according to claim 11, wherein in the image forming apparatus determining step, the determining is performed in accordance with a selection made by a user who has observed the output patch pattern. 15. The image processing according to claim 9, wherein the calibration execution step holds the patch pattern to be output corresponding to each of a plurality of image forming apparatuses. Method. 16. An image processing method for controlling an image forming apparatus to output an image to the image forming apparatus, wherein the color reproduction capability of the image forming apparatus for outputting an image is determined, and the determination result based on the determination is determined. Determining a type of a test pattern to be used for calibration based on the image processing method. 17. A storage medium storing a program readable by an information processing apparatus, wherein the program is an image processing for controlling an image forming apparatus and causing the image forming apparatus to output an image. An image forming apparatus for performing output, and a step of calibrating the image forming apparatus for performing image output, the image forming apparatus determining a patch pattern corresponding to the image forming apparatus determined by the determination unit; And a process of executing calibration based on the output patch pattern. 18. A storage medium storing a program readable by an information processing apparatus, wherein the program is an image processing for controlling an image forming apparatus and causing the image forming apparatus to output an image. A storage medium, which is a process having a step of determining a color reproduction capability of an image forming apparatus for performing output, and determining a type of a test pattern used for calibration based on a result of the determination.