JP2003345074A - Image processing system and calibration method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly precisely calibrate any printer including a printer which does not have a density measuring instrument such as a scanner in an image processing system constituted by connecting a plurality of printers. <P>SOLUTION: When it is determined that it is time to perform density correction processing, it is determined whether an SCAL table is present in a density correction table of a color LBP (S902) and when no SCAL table is present, a color LBP having the SCAL table is searched for (S903). The SCAL table is obtained from the printer with the SCAL table which is thus searched for. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing system and a calibration method, and more specifically, to print output characteristics such as print density and tint in a printing device such as a printer connected via a network in the image processing system. It is related to the calibration for correcting.

[0002]

2. Description of the Related Art A printing device is known as one of devices that output information processed by an information processing device such as a computer. As such a printing device, a device using an electrophotographic method such as a laser beam printer (hereinafter referred to as “LBP”) is widely used. This kind of printer has many advantages such as high quality printing result, quietness and high speed, and is one of the factors for rapidly expanding the field of desktop publishing. In addition, color images can be easily handled by improving the performance of the host computer and the controller that is the image generation unit of printers, and printers that can print color images have become widespread in addition to conventional monochrome image printing. It's starting.

By the way, it is known that in these printers and the like, the tint, the density, etc. of the output image may change while the printout is performed for a long period of time. This is due to a change in print output characteristics of a printer or the like with time and an increase in variations among devices. In addition, such changes in print output characteristics or the like generally have individual differences among devices, including the above-described changes over time that cause the changes. In this case, for example, in an image processing system in which a plurality of printers are connected, the color tone and the like may be different between the printers.

In the case of the above-mentioned LBP which uses an electrophotographic system as an image forming system, such a change in characteristics is caused by laser exposure in the electrophotographic process, latent image formation on a photoconductor, and development with toner. , The process of transferring a toner image to a printing medium such as paper and fixing with heat is easily affected by the temperature and humidity around the device or changes over time of the components, and the amount of toner finally fixed on the paper is It is caused by changing. It is known that such a change in the print output characteristic is not unique to the electrophotographic method, and occurs similarly in the inkjet method, the thermal transfer method, and various other methods.

In order to solve the above-mentioned problems, it has been conventionally known to perform calibration for correcting, for example, the density of print output at a predetermined timing or when necessary.

One form of calibration in an electrophotographic printing apparatus is such that a calibration process is automatically started every time a predetermined number of sheets or a predetermined time is printed. In this processing, for example, a patch pattern of a predetermined density level at a plurality of points is formed as a toner image on the intermediate transfer member in the device, and the density of those patches is measured by a sensor also provided in the device. Based on the above, the density correction table is created or updated so that the input density level in the print data becomes a predetermined standard density value. Then, in the subsequent printing, by correcting the input density level of the print data with this density correction table, it is possible to always maintain the density or tint of the print output within a certain range according to the input density level. It will be possible.

Further, as another calibration method capable of improving the accuracy of this automatically performed calibration, there is also known a method that uses a calibration using a density measuring device such as a scanner together. That is, the calibration based on the measurement result of the patch pattern formed on the intermediate transfer member is different in the measured density from the density printed on the actual printing paper, and thus the calibration accuracy is relatively low. May be. Therefore, in a printing apparatus equipped with a density measuring device such as a scanner, in addition to the one using this intermediate transfer member, a density correction table obtained by printing a patch pattern on a sheet is used as a reference or standard correction table. Then, this is combined with the automatically obtained density correction table to be used. The density correction table by combining is a density correction table configured by sequentially using two tables related to combining and converting. As a result, even if the calibration using the density measuring device such as a scanner is not frequently performed, the accuracy can be made higher than a certain level by the calibration automatically performed in the device on the basis of the calibration. At the same time, even if printing is performed for a predetermined number of sheets or for a predetermined period of time and the print characteristics change, the change can be dealt with by the above-described automatic calibration that is activated in response to the change.

[0008]

However, in an image processing system in which a plurality of printing devices are connected via a network, if there is a difference in accuracy due to the above-mentioned difference in calibration method between the printing devices. Is
Even if the calibration is performed in each device, there is a problem in that the print output characteristics as a result of the calibration are relatively large and the print results obtained by the devices are different. Specifically, an apparatus that forms a patch on the intermediate transfer member for calibration inside the apparatus, and a scanner is provided, and the patch is printed on a sheet of paper and read by the scanner. If devices capable of performing calibration are mixed and connected to the network, the above-mentioned problem occurs.

On the other hand, for example, an application program for calibration is started on the host computer to perform an operation related to the calibration, and in a printer not equipped with a scanner, the paper is not on the intermediate transfer body in the apparatus. It is also conceivable to print a patch on the printer, read it with a scanner of another printer, and process the result with a host computer to create a density correction table as a reference for a printer not equipped with the scanner. . However, in order to read the patch pattern, it is necessary to move to a place where a printer equipped with a scanner or the like is installed and perform an operation, which causes a problem that the operation becomes complicated. Further, when performing the above-described calibration on all of the plurality of printers that are not equipped with a scanner, it is necessary to perform the above-mentioned operation on all of the printers, and the labor may be enormous. there were.

The present invention has been made to solve the above problems, and an object of the present invention is to connect a plurality of printing devices including a printing device not equipped with a density measuring device such as a scanner. It is an object of the present invention to provide an image processing system and an image processing method capable of performing highly accurate calibration in any printing apparatus.

[0011]

To this end, according to the present invention, a plurality of printing devices are connected to each other so as to be able to exchange data with each other, and the plurality of printing devices perform predetermined data conversion related to image processing. A first printing device that holds first reference data conversion data in correspondence with the printing characteristics of the printing device; and a first printing device that does not hold the first data conversion data as corresponding to the printing characteristics of the printing device. An image processing system including two printing devices, wherein the second printing device acquires second data conversion data for the predetermined data conversion in association with printing characteristics of the second printing device. The conversion data acquisition unit acquires the first data conversion data from the first printing device, and the reference first data conversion data and the second data conversion data acquired by the conversion data acquisition unit. Over data conversion is characterized by having a correction means for performing a calibration of the correction to the second printer the second data conversion data to a predetermined conversion characteristic.

Further, a plurality of printing devices are connected to each other so as to be able to exchange data with each other, and the plurality of printing devices use the first data conversion data as a reference for predetermined data conversion related to image processing. In an image processing system including a first printing device that holds the printing characteristics of the printing device and a second printing device that does not hold the first data conversion data as the printing characteristics of the printing device. A calibration method, wherein the second printing device acquires second data conversion data for the predetermined data conversion in association with printing characteristics of the second printing device. The first data conversion data is acquired, and the data conversion by the reference first data conversion data and the second data conversion data acquired by the conversion data acquisition means is a predetermined conversion characteristic. So as to correct the second data conversion data to perform the calibration of the second printing unit, characterized in that comprising the step.

According to the above configuration, the first data conversion data is acquired from the first printing device that holds the first data conversion data as the reference, and the first data conversion data of the reference and the first data conversion data related to the calibration are acquired. The second data conversion data is corrected so that the data conversion by the second data conversion data acquired by the second printing device has a predetermined conversion characteristic, and the calibration of the second printing device is executed. Even if the device does not hold, for example, the first data conversion data having a high comparison accuracy as the device's reference, it is possible to correct the second data conversion data with reference to it.

[0014]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

In the following description, the present invention will be described as 600d.
An embodiment applied to an image processing system connected to a color LBP for printing at a resolution of pi will be described, but the present invention is not limited to this, and a color printer or a color facsimile apparatus having an arbitrary printing resolution, and further, Of course, it can be applied to an image processing system to which a printing device such as a copying machine is connected.

(First Embodiment) FIG. 1 is a block diagram showing the arrangement of an image processing system according to an embodiment of the present invention.

The image processing system of this embodiment is configured by connecting a host computer 101, a color LBP 102 having a scanner 104 as a density measuring device, and a color LBP 103 having no scanner via a network 100. . In FIG. 1, two color LBPs 103 are shown as an example, but it goes without saying that the number of printing devices is not limited to this, and the connected printing device is not limited to a printer, and a facsimile is used. A device or a copying machine may be connected. In this case, the copying machine can have its original reading portion function as a density measuring device as a scanner for the purpose of calibration.

In FIG. 1, reference numeral 100 denotes a network, which is generally known as a system called Ethernet (registered trademark), and is connected by a protocol such as TCP / IP using a physical cable such as 10BaseT. Information can be exchanged and data can be transferred between the respective device units. Reference numeral 101 denotes a host computer, which prints color information, characters, figures, image images, the number of copies, and other print information for performing print processing in the color LBP1.
02 and 103. 102 and 103 are color LBs
P is shown, and all have the same function. 1
Reference numeral 04 denotes a scanner, which can read a normal image and the like, and can also measure the density of a patch pattern for calibration (also referred to as “density correction processing” in this specification) described later.

Color LBP to which the scanner 104 is connected
An image processing unit 106 and a control unit 107 are configured in 102, and these are connected to each other via a bus (not shown) and a network via a network interface (hereinafter also referred to as “network I / F”) 105. It is connected to 100. The image processing unit 106 sends an image signal or the like to the printer engine 108, and the printer engine performs actual image formation, that is, a printing operation based on this.

Further, the image processing unit 106 obtains the density measurement information from the density measuring unit 112 which measures the density value of the density level, and based on this, performs the process relating to the automatic calibration inside the main color LBP. That is, the density measuring unit 112 is configured to have a density sensor provided adjacent to the intermediate transfer member, as will be described in detail with reference to FIG. The density of the patch formed on the intermediate transfer member is measured in the calibration started at a predetermined timing such as time, and the density information is output to the image processing unit 106. As described above, the calibration according to the embodiment of the present invention is performed on the premise that it is executed in the printing apparatus as described in the related art, and the calibration information based on the density measuring apparatus such as a scanner is used as a reference. It is also used as information. The configuration and the like will be described later.

The control unit 107 controls the operation of the entire color LBP.
This is possible by transmitting a control signal for judging and controlling various processes to the control unit 107 according to the control program 110a stored in 110. Further, the RAM 111 is used as a work area for storing data for the CPU 109 to perform each control.

On the other hand, the color LBP 103 has basically the same configuration as the color LBP 102 described above, and includes an image processing unit 106, a control unit 107, a CPU 109, and a ROM.
110, a RAM 111, a printer controller 114 including a density measuring unit 112, and a printer engine 115, and is connected to the network 100 via a network I / F 113. Therefore, the color LBP
The difference from 102 is that the scanner 104 is not connected.

FIG. 2 is a block diagram showing the detailed arrangement of the image processing unit 106 in the color LBP 102.

In the figure, reference numeral 161 denotes a reception buffer, which holds print information input via the network. Reference numeral 162 denotes an object generation unit, which is intermediate information (hereinafter referred to as “object”) of information (page description language) such as colors, characters, figures, and image images, which is print information input from the host computer 101 as described above. Perform processing to convert to. An object buffer 163 stores the object obtained by the conversion by the object generation unit 162 for one page of printing. Here, when the print information includes information on color level data such as gray level settings, color level settings, and multi-valued image images, the density correction processing unit 167 uses the density correction table 171 to print the density of these print data. Correct the level.

More specifically, the density correction table 171
Is a scanner density correction table (hereinafter referred to as “SCAL table”) 171a created by the scanner density correction processing unit 169 based on the density of the patch pattern measured by the scanner 104 by calibration.
And a density measurement table (hereinafter referred to as “PCAL table”) 171b created by the in-printer density correction processing section 170 using the density value of the patch pattern measured by the density measurement section 112, as will be described later. The correction table is created by the correction processing unit 168.
Then, the density correction processing unit 167 performs density correction using the density correction table 171.

Reference numeral 164 denotes a rendering unit, which performs rendering processing based on the object for one page stored in the object buffer 163 and converts it into a bitmap to be rendered. At this time, the dither processing unit 16
Reference numeral 6 performs pseudo halftone processing to generate multivalued bitmap data according to the number of output gradations in the printer engine. Reference numeral 165 denotes a band buffer, which stores the bitmap generated by the rendering unit 164 and sends the bitmap data according to the printing operation in the printer engine 108.

FIG. 3 is a block diagram showing the detailed arrangement of the image processing unit in the printer controller 114 of the color LBP 103.

2 is different from FIG. 2 in that the scanner density correction processing unit 169 is not provided, and in connection with this point, the color LBP 10 is connected via the network 100.
No. 2 SCAL table 171a is received by the reception buffer 161, and the SCAL table 1 of the density correction table 171 is received.
This is the point to be stored as 71a. That is, in the embodiment of the present invention, the calibration in the LBP 103 not including the scanner is basically performed based on the density measurement information from the density measuring unit 112, but in order to improve the accuracy, the calibration is obtained using the scanner. The calibration information SCAL table 171a is acquired from the LBP 102 that created the table, and the PAL table 171a is set based on the density measurement information from the density measurement unit 112 with reference to this.
Create a CAL table. As a result, the density correction table obtained by combining the created PCAL table and the acquired SCAL table can be made highly accurate.

Except for the above points, the LBP1 shown in FIG.
02, the description thereof will be omitted here.

FIG. 4 shows each of the color LBPs 102,
3 is a flowchart showing the overall processing relating to printing in 103. The control program that realizes the processing shown in the figure is stored in the ROM 110 as described above and is executed by the CPU 109.

In FIG. 4, first, the color LBP 102,
As the initialization processing of 103, printer status initialization and buffer initialization are performed (step S401).
Next, print data (print information) is received from the host computer 101 (step S402), and the reception buffer 1
It is held at 61 (step S403). Then, one processing unit, for example, one page of data is extracted from the reception buffer 161 (step S404), and then it is determined whether or not all data is extracted (step S40).
5). If it is determined in step S405 that the processing has not been completed, it is determined whether data processing for one page has been completed (step S406).

When it is determined in step S406 that the print data is not completed, it is determined whether the print data is color-related data such as color information or a color image image (step S407), and the data is color-related data. In this case, the density correction processing unit 167 corrects the density level of the print data, which is the color-related data, using the density correction table 171 (step S408). Then, the object generator 162 generates an object (step S409), stores it in the object buffer 163 (step S410), and returns to step S404.

On the other hand, if it is determined in step S407 that the data is not color-related data, it is determined whether the data is mask data for characters, figures, etc. (step S41).
1) If it is mask data, an object of mask data is created (step S409), stored in the object buffer 163 (step S410), and the process returns to step S404. If it is determined in step S411 that the data is not mask data, print data processing is performed according to the type of data (step S412), and the process returns to step S404.

When it is determined in step S406 that the data processing for one page described above is completed,
Rendering processing is performed by the rendering unit 164 based on the object held in the object buffer 163 (step S413), and a bitmap image is transmitted to the printer engine 108 to perform printing processing for printing on paper (step S414). . If it is determined in step S405 that all data have been processed, this process ends.

FIG. 5 shows a color LBP1 equipped with a scanner.
2 is a flowchart showing an outline of a process related to calibration executed in 02. That is, in this calibration, in addition to the in-apparatus calibration using the intermediate transfer member, the calibration using the scanner is also performed. This creates the SCAL table and PCA based on this SCAL table.
This is a process of correcting the L table and setting the combined density correction table for these L tables. The scanner density correction processing unit 169, the printing device internal density correction processing unit 170, and the correction table correction processing unit 168 are directly performed.
It is a flowchart which shows the process performed by.

In FIG. 5, first, in step S501, scanner density correction (calibration) is performed using the scanner 104 connected to the color LBP 102,
Create a SCAL table. This process is described in detail in FIG.

Next, in step S502, the color LB
A patch pattern consisting of patches of several density levels is formed on the intermediate transfer member in P102, and the density is similarly set to LB.
It is measured by a sensor provided in P102. Then, the data of the above-mentioned input density levels at the time of forming these patches and the measured density values corresponding thereto are stored in a predetermined memory.

Then, in step S503, the SCAL table created in step S501, the concentration level and measured concentration value data obtained in step S502 are retrieved, and the PCAL table is retrieved. Then, in step S504, as will be described in detail later with reference to FIG. 13, the variation amount of the PCAL table is obtained from the data of the concentration level and the measured concentration value, and based on this and the standard SCAL table, the PCAL table is stored. Correct the content. This allows the SCAL table and P
The density correction table obtained by correcting the CAL table may be one having linear characteristics, and this is written in the density correction table 171 (step S50).
5) Then, this process ends.

FIG. 6 is a flow chart showing the details of the scanner density correction processing in step S501, which is the processing directly executed by the scanner density correction processing unit 169.

In FIG. 6, first, in step S601, a scanner density correction patch pattern is printed on a sheet.
FIG. 7 is a diagram showing an example of a scanner density correction patch pattern, in which a sufficient number of patches are obtained for each color of Y, M, C, and K to obtain the density characteristics of the density level with respect to the input density level 0-255. In order to eliminate an error due to uneven density that may occur depending on the printing position on the paper, patch patterns having the same density level are arranged at different positions. This patch pattern can be printed by a command from the host computer 101 or the test print function of the color LBP 102. Next, the density value of each density level of the patch pattern printed in step S601 is measured using the scanner 104 (step S6).
02), averaging processing is performed on the measured density values for the same density level in order to reduce the influence of uneven density on the paper (step S603), and moving average is performed using the density values of the preceding and following density levels. As a result, the measured density value is corrected (step S604). Then, based on the corrected measured density value for each density level, a scanner density correction table (hereinafter referred to as "S") that makes the density characteristic with respect to the input density level a predetermined density characteristic (linear characteristic).
CAL table ”) is created in the density correction table 171 (step S605), and this processing ends.

FIG. 8A is a diagram showing an example of the relationship between the density level when printing a patch and the density measurement value measured by the scanner in the calibration using the scanner. (b) is a figure which shows typically the SCAL table corrected based on the relationship.

More specifically, the solid line shown in FIG. 8A indicates that the scanner density correction patch pattern shown in FIG. 7 is printed by the processing of steps S601 to S604 shown in FIG. The density characteristic is the density characteristic with respect to the patch input density level obtained from the corrected measurement value. That is, the color LBP 102 at that time
Shows a constant print density characteristic of. On the other hand, the broken line shown in FIG. 8A shows a predetermined density characteristic which is a predetermined calibration target and has a linear characteristic in the present embodiment.

The solid line shown in FIG. 8B shows the contents of the SCAL table actually created, that is, the relationship of density conversion (correction). By performing density correction of print data using this density correction table, In printing, the density characteristic shown by the solid line in FIG. 8A can be made the linear characteristic shown by the broken line in FIG. 8A.

FIG. 9 is a flow chart showing an outline of the processing relating to the calibration executed in the color LBP 103. This process is directly performed by the in-printer density correction processing unit 170 and the correction table correction processing unit 168.
This is the process executed by.

In FIG. 9, first, step S901.
Then, it is determined whether the main color LBP 103 executes the density correction processing (calibration). That is,
This density correction processing is performed at power-on, after printing a predetermined number of sheets, for example, a predetermined number of sheets after printing 50 sheets or 200 sheets after the power is turned on, or a predetermined time, for example, every 30 minutes. Is started when a predetermined time has passed, and when environmental fluctuations such as the temperature and humidity inside the device reach predetermined values.

When it is judged in step S901 that it is the execution timing of the density correction processing, it is judged whether or not the SCAL table 171a exists in the density correction table 171 of the color LBP 103 (step S902).
If the table 171a does not exist, the color LBP that owns the SCAL table is searched (step S9).
03). That is, the color LBP connected to the network is searched, and the color LBP 102 which owns the SCAL table is determined based on the identification symbol stored in the RAM 111 of each printer as the SCAL table possessing printer identification information. In addition, SCAL
The IP address of the color LBP in the network can be used as the table-owned printer identification information. In step S904, as described above, in step S90
The SCAL table is obtained from the SCAL table-owning printer found in step S3.

As described above, in the embodiment of the present invention, even in a printing apparatus not equipped with a scanner, in order to improve the accuracy of the calibration in the apparatus, it can be obtained by using a density measuring apparatus such as a scanner in another printing apparatus. The resulting SCAL table is used as a reference table.

Next, in steps S905 to S908,
Similar to steps S502 to S05 in FIG. 5, a patch pattern having several density levels is formed on the intermediate transfer member in the color LBP 103, and the density is measured using a sensor. And this and the SCA obtained above
The PCAL table is corrected on the basis of the L table, a combined density correction table having a linear characteristic is created, and is written in the density correction table 171, and this processing is ended.

In step S902, the color LBP
If the SCAL table 171a has already been fetched and exists in the density correction table 171 of 103, the processing of steps S903 and S904 is not performed, and the process proceeds to step S905.

From the above, regarding the printer, for example,
Even if the patch pattern is printed on a sheet of paper and the printer equipped with a scanner is installed and a complicated operation such as reading is not performed, a calibration that is not so inferior in accuracy to that using a scanner can be specified. It becomes possible to execute at a relatively frequent timing such as every number of sheets.

FIG. 10 is a flow chart showing the process of creating a standard PCAL table. That is,
As described with reference to FIGS. 5 and 9, the PCAL table is corrected at a predetermined timing such as every time a predetermined number of sheets are printed.
The process of creating the L table is shown. It should be noted that this process is performed as an initial process in each printer, for example.

In FIG. 10, first, as schematically shown in FIG. 11, the patch pattern 201 is formed on the intermediate transfer body 202.
Are formed (step S1001), and their concentrations are measured by the sensor 203 (step S1002). Here, FIG. 11 is a diagram schematically showing an example of the density measuring process in the printing apparatus. As shown in FIG. 11, Y, M, C, K
The patch pattern 201 is formed on the intermediate transfer body 202 for each of the three halftone density levels in the range of density levels 0 to 255 for each color, and the density of each patch is measured by the sensor 2.
It is measured by 03. In the present embodiment, the patch pattern 201 is a patch pattern of density levels 30H, 60H, 90H for each of Y, M, C, and K colors.

The formation and measurement of the patch pattern described above are performed in the same manner as described with reference to FIGS. 5 and 9.

Next, the density level of each patch and the density value formed by the sensor and measured by the sensor are received (step S1003), step S1004,
A PCAL table is created in 1005.

Specifically, using the SCAL table, the density levels for forming each patch received above are
The conversion relationship of the SCAL table, specifically, FIG. 8 (b)
When the correction density level value on the correction density level axis in the relationship shown in (4) is set, the input density level value on the input density level axis in FIG. 8B corresponding to the correction density level value is calculated (step S1004). Then, the obtained input density level value is used as a reference density level value, and the density measurement value by the sensor is used as a sensor reference value, and the relationship between these reference density level values and the sensor reference value is used as a PCAL table 171b. Is set (step S1005).

An example of the sensor reference value set by the above processing is indicated by ● (black dot) in FIG.
That is, the created PCAL table defines the relationship between the reference density level value and the sensor reference value so as to include the inverse conversion relationship of the SCAL table, and this will be described later in detail in FIG. As described above, the correction table obtained by synthesizing the SCAL table and the PCAL table can have, for example, a linear relationship in which the relationship between the reference density level value and the sensor reference value is as shown in FIG. In other words, the PCAL table is created with the SCAL table as a reference to correct the correction table with high accuracy.

FIG. 13 is a flow chart for explaining the details of the correction table correction processing of steps S504 and S907 in FIGS. 5 and 9, respectively. Directly to the correction table correction processing units 168 of the color LBPs 102 and 103, respectively. It shows the processing by.

First, in step S1301, the input density level value when forming a patch and the density value measured by the sensor are received from the in-printer density correction processing unit 170, and the sensor density measurement value and the density correction table 171 are retrieved. In the standard PCAL table 171b,
The sensor reference value corresponding to the density level value is compared. Then, the density fluctuation amount of the sensor density measurement value from the sensor reference value is calculated by this comparison (step S130).
2). Further, the density characteristic when the table conversion is performed is calculated by the density correction table 171 based on the calculated density fluctuation amount, and the conversion characteristic of the density correction table 171 by this combination is a predetermined density characteristic, in the present embodiment. The PCAL table is corrected with the SCAL table as a reference so that the linear characteristic is obtained (step S13).
03).

FIGS. 14A to 14C are views for specifically explaining the table correction process.

FIG. 14A is a diagram showing the relationship between the input density level and the measured density value of the patch formed based on the data converted by the density correction table 171. In the figure, the broken line shows the density characteristic of the density correction table obtained by combining when the standard PCAL table is created, and has a predetermined density characteristic (linear characteristic). The black circle on the broken line indicates the sensor reference value, and the white circle on the solid line indicates the sensor measurement value. The density difference between the sensor reference value ● and the sensor measured value ○ is the density fluctuation amount. According to this density fluctuation amount, the density correction table 17 at that time
The density characteristic obtained by the correction according to 1 is shown in FIG.
The density characteristic is shown by the solid line.

When the PCAL table is corrected so that the density characteristic shown by the solid line in FIG. 14A becomes a predetermined density characteristic (linear characteristic), the contents are shown by the solid line in FIG. 14B. Become.

In the density correction table obtained by combining the SCAL table and the PCAL table, that is, in the density correction table configured to sequentially use these two tables, the solid line in FIG. 14 (b) is used. The PCAL table shown is the SCA shown by the solid line in FIG.
Since it is the correction table of the input density level corrected by the L table, the PAL table shown by the solid line in FIG. 14B and the SCAL table shown by the solid line in FIG. The correction is performed, and finally, the density correction table shown by the solid line in FIG. 14C can be obtained.

A color LBP 10 equipped with a scanner
The calibration performed at a predetermined timing, such as every time a predetermined number of sheets are printed in 2, does not necessarily have to be accompanied by the process of creating the SCAL table using the scanner shown in FIG. Color LB without scanner
As in the case of P103, it is of course possible that calibration is performed only in the apparatus in which a patch is created in the apparatus, read by a sensor, and the SCAL table stored is used as a reference to correct the PCAL table. is there.

(Second Embodiment) In a second embodiment of the present invention, a printer not equipped with a density measuring device such as a scanner is equipped with the SCAL table so as to acquire the SCAL table.
When one is selected from the plurality of printers storing the table, the printer having the closest characteristic indicated by the PCAL table is selected and the SCAL table is acquired from this. This makes the standard SC
PC that corrects the AL table using this for printing characteristics
The AL table can be made more suitable, and the calibration accuracy can be further improved.

FIG. 15 is a block diagram showing the arrangement of an image processing system according to the second embodiment of the present invention, which is similar to FIG. 1 according to the first embodiment. In the configuration shown in these drawings, the point that this embodiment is substantially different from the first embodiment described above is that, as shown in FIG. 15, in this embodiment, two color LBPs 102 each having a scanner 104 are connected. That is the point. That is, the image processing system according to the present embodiment includes a scanner and an SC obtained by using the scanner.
Holds the AL table and SCALs from other LBPs 103
A plurality of printers are connected as printers selected to obtain the table. Of course, the number of printers is not limited to two, and any number of printers may be used as long as it is two or more.

In FIG. 15 and subsequent figures according to the second embodiment, the same elements as those described in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 16 shows the color LBP1 shown in FIG.
2 is a block diagram showing details of an image processing unit 106 in 02. FIG. The configuration shown in FIG. 16 is substantially the same as the configuration shown in FIG. 2 regarding the first embodiment. That is, the density measuring unit 112 having a sensor for detecting the density of the patch formed on the intermediate transfer member is shown as the configuration of the image processing unit 106. However, the function for exerting the action and effect of the present invention is the above-mentioned. It is the same as the first embodiment, and is not substantially different.

Further, the image processing unit 106 of this embodiment is
The transmission buffer 172 is provided. This send buffer 1
72 is a SCAL table 171 read from the density correction table 171 in response to a request from the LBP 103.
a and the PCAL table 171b to the network I /
F, and further to the LBP 103 via the network 100. As described above, the transmission buffer 172 is shown in FIG. 16, but in the above-described first embodiment, the S buffer is sent in response to a request.
Similar elements for sending CAL table to LBP103
(Not shown in FIG. 2).

FIG. 17 is a block diagram showing the detailed arrangement of the printer controller 113 in the LBP 103.

The difference from the configuration shown in FIG. 3 according to the first embodiment is that the own PCAL table and the PCAL table acquired from the LBP 102 are compared and the LBP 102 having the PCAL table having the closest characteristic is selected and the This is a point regarding the configuration in which the SCAL table is used as a calibration reference table.

That is, as will be described later in detail with reference to FIGS. 18 to 20, the SCAL table 171a and the PCAL obtained together with the identification symbol from the density correction table 171 of the LBP 102 via the network I / F 113 and the network 100. The table 171b is stored in the reception table storage unit 175. Further, the PCAL table comparison unit 174 compares the PCAL table stored in the reception table storage unit 175 with the PCAL table 171b stored in the density correction table 171, and compares the SCAL table of the printer having the closest PCAL table characteristic with the density correction table. It stores in the SCAL table 171a on 171.

Of the processing by the configuration of this embodiment shown in FIGS. 15 to 17 and other components, the same processing as that described in the first embodiment will be omitted, and only different processing will be described below.

FIG. 18 shows the color LBP 10 of this embodiment.
10 is a flowchart showing an outline of a calibration-related process executed in No. 3, which is the same process as the process described in FIG. 9 for the first embodiment.

In FIG. 18, first, step S1801.
Then, as in the first embodiment, it is determined whether or not the color LBP 103 executes the density correction processing, and when it is determined that it is time to execute the density correction processing, the SCAL table 171a is stored in the density correction table 171. Whether or not it exists (step S1802), and if the SCAL table 171a does not exist, the color LBP 102 that owns the SCAL table is searched (step S1).
803). That is, the color LBP connected to the network is searched, and the determination is made based on the identification symbol stored in the RAM 111 of each printer as the SCAL table possessing printer identification information.

Next, S searched in step S1803
From all printers that own the CAL table, the SCAL table and P
The CAL table is acquired (step S1804) and stored in the reception table storage unit 175 (step S180).
5). Then, as will be described later in detail with reference to FIG. 19, the PC of each printer stored in step S1805.
The AL table and the PCAL table 171b stored in the density correction table 171 are compared (step S1
806) Identify the printer that owns the PCAL data showing the closest characteristic. Then, the SCAL table of the identified printer is acquired from the reception table storage unit 175 (step S1807).

Next, as in the first embodiment, a patch pattern having several density levels is formed on the intermediate transfer member in the color LBP 103, and the measured pattern is measured by using a sensor. Data indicating the relationship is obtained (step S1808). Next, the density correction data obtained in step S1808 is taken out (step S1809),
Based on this and the SCAL table acquired in step S1807, the standard PCAL table is corrected in the same manner as described with reference to FIG. 13, so that the density characteristic becomes a predetermined density characteristic (linear characteristic). A composite density correction table is created (step S1810). Then, the created table is used as the density correction table 171.
(Step S1811), and this processing ends.

FIG. 19 is a flow chart showing details of the comparison process described in step S1806 of FIG. In this comparison processing, for each of the predetermined N same density levels in the mutual PCAL tables to be compared, the difference in the density values corresponding thereto is found in the table, and the PCAL table having the smallest average is the table having the closest characteristic. This is the process.

In FIG. 19, first, step S190.
In step 1, it is determined whether or not all the PCAL tables for each printer managed by the identification code stored in the reception table storage unit 175 have been retrieved. If not all are taken out, it is determined whether or not the density level of the PCAL table of the printer to be processed is the final density level N related to the processing (step S1902). When the density level is equal to or lower than the final density level N, the density value DLEVEL corresponding to the predetermined density level in the extracted PCAL table and the density correction table 171 are stored in the density correction table 171 and the correction in step S1810 has not been performed yet. Error DERR with the density value DLEVELT corresponding to the same density level in the PCAL table at that time, which has been already corrected by the calibration of step S1902, is calculated by the following equation (step S1903).
Return to. In this manner, the density number of the predetermined number N is sequentially changed, and the processing for obtaining the error of the density value corresponding thereto is performed. DERR = | DLEVELT-DLEVEL | In this way, the process of sequentially changing the predetermined number of density levels and obtaining the error of the density value corresponding thereto is performed.

On the other hand, when it is determined in step S1902 that the processing has been completed for all the predetermined number N of density levels in the PCAL table of the printer concerned, the average error DEave is calculated by the following formula (step S
1904) and the process returns to step S1901. DEave = ΣDERR / N If it is determined in step S1901 that all PCAL tables for each printer managed by the identification symbol have been extracted, this processing ends.

FIG. 20 is a diagram for explaining the above-mentioned comparison processing, and is a diagram for explaining the contents of the PCAL table stored in the density correction table 171 and the PCAL table of each printer stored in the reception table storage unit 175. is there. In the figure, ● on the broken line is the density correction table 1
The density values DLEVELT corresponding to N predetermined density levels in the PCAL table (in this case, for example, showing the initial linear PCAL table) stored in 71 are shown, while the circles on the solid line are managed by the identification symbols. 7 shows the density value DLEVEL stored in the reception table storage unit 175 for two printers for the same density level in their PCAL tables. The length of the line segment between each black circle and the white circle is the above error. In the example shown in FIG. 20, the PCAL table of the printer A is closer to the characteristics of the PCAL table of the color LBP 103 related to the calibration process than the PCAL table of the printer B.

As described above, according to this embodiment, the PC
Since the printer having the characteristics closest to the AL table is selected and the SCAL table is acquired from this, the reference SCAL table can be made more suitable for the PCAL table that is corrected by using the printing characteristics. The calibration accuracy can be further improved.

(Other Embodiments) Even if the present invention is applied to a system composed of a plurality of devices (for example, host computer, interface device, reader, printer, etc.) as described above, one device (for example, a copying machine) is used. , A facsimile machine).

Further, a diagram for realizing the functions of the above-described embodiment in a computer in an apparatus or system connected to the various devices so as to operate the various devices so as to realize the functions of the above-described embodiments, 4, Figure 5,
The program code of the software shown in FIGS. 6, 9, 10, 13, 18, and 19 is supplied to the computer (CPU or MP) of the system or apparatus.
The operation of U) performed by operating the various devices according to the stored program is also included in the scope of the present invention.

Further, in this case, the program code itself of the software realizes the function of the above-described embodiment, and the program code itself and means for supplying the program code to the computer, for example, such program code are The stored storage medium constitutes the present invention.

A storage medium for storing the program code is, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, a CD-R.
An OM, a magnetic tape, a non-volatile memory card, a ROM or the like can be used.

Further, not only the functions of the above-described embodiments are realized by executing the supplied program code by the computer, but also the OS (operating system) in which the program code is operating in the computer, or another Needless to say, the program code is also included in the embodiments of the present invention when the functions of the above-described embodiments are realized in cooperation with application software or the like.

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

[0088]

As described above, according to the present invention, the SCAL table is acquired from the LPB (102) serving as the first printing device that holds the SCAL table serving as the first data conversion data serving as the reference, and the SCAL table is acquired. Density correction as data conversion by the reference SCAL table and the data related to the PCAL table as the second data conversion data acquired by the LBP (103) as the second printing device related to calibration has a predetermined characteristic, for example, linear Since the data relating to the PCAL table is corrected so that the LBP (103) is calibrated, a SCAL table with a high comparison accuracy, such as the LBP (103) serving as a reference, is set as a device-specific one. Correction of data related to PCAL table based on it even if it is not held It can be carried out.

As a result, in an image processing system configured by connecting a plurality of printing devices, high-precision calibration is executed in any printing device including a printing device not equipped with a density measuring device such as a scanner. It becomes possible.

[0090]

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image processing system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of an image processing unit 106 in the color LBP 102 shown in FIG.

3 is a block diagram showing a detailed configuration of an image processing unit in a printer controller 114 of the color LBP 103 shown in FIG.

FIG. 4 is a flowchart showing the overall processing relating to printing in each of the color LBPs 102 and 103.

FIG. 5 is a flowchart showing an outline of a calibration-related process executed in the color LBP 102.

FIG. 6 is a flowchart showing details of scanner density correction processing of step S501 in the processing of FIG.

7 is a diagram showing an example of a scanner density correction patch pattern used in the processing shown in FIG.

8A is a diagram showing an example of a relationship between a density level at the time of printing a patch and a density measurement value measured by the scanner in the calibration using the scanner shown in FIG. b) is a diagram schematically showing a SCAL table corrected based on the relationship.

FIG. 9 is a flowchart showing an outline of a process related to calibration executed in the color LBP 103.

FIG. 10 is a flowchart showing a process of creating a standard PCAL table.

FIG. 11 is a diagram schematically showing an example of the in-printer density measurement processing.

12 is a diagram showing characteristics of a density correction table obtained by combining the standard PCAL table shown in FIG. 10 with the SCAL table when the standard PCAL table was created.

FIG. 13 is a flowchart for explaining details of the correction table correction processing particularly in steps S504 and S907 in FIGS. 5 and 9, respectively.

14A to 14C are diagrams for specifically explaining the table correction process.

FIG. 15 is a block diagram showing a configuration of an image processing system according to a second embodiment of the present invention.

16 is a block diagram showing a detailed configuration of an image processing unit 106 in the color LBP 102 shown in FIG.

17 is a block diagram showing a detailed configuration of a printer controller 114 of the color LBP 103 shown in FIG.

FIG. 18 is a flowchart illustrating an outline of a calibration-related process executed in the color LBP 103 according to the second embodiment.

FIG. 19 is a flowchart showing details of the comparison processing described in step S1806 of FIG.

FIG. 20 is a diagram illustrating the above comparison processing.

[Explanation of symbols]

100 network 101 host computer 102, 103 color laser beam printer (color LBP) 104 scanner 105, 113 network interface (network I / F) 106 image processing unit 107 control unit 108, 115 printer engine 109 central processing unit (CPU) 110 Read-only memory (ROM) 111 Random access memory (RAM) 112 Density measuring unit 114 Printer controller 161 Reception buffer 162 Object generation unit 163 Object buffer 164 Rendering unit 165 Band buffer 166 Dither processing unit 167 Density correction processing unit 168 Correction table correction processing 169 Scanner density correction processing unit 170 In-printer density correction processing unit 171 Density correction table 171a SCA Table 171b PCAL table 174 PCAL table comparing unit 175 receives the table storage unit 201 patch pattern 202 intermediate transfer member 203 sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G06T 5/00 100 G03G 21/00 372 F term (reference) 2C061 AP01 AP03 AP04 AQ06 AR01 HJ10 HK11 HQ01 2C187 AC07 AD03 AD04 AE11 AF03 CC08 FC06 GA01 2H027 DA09 DA12 DA14 DA38 DA45 EC18 EE08 EF01 EJ13 EJ15 ZA07 5B057 CA01 CA08 CB01 CB08 CE11 CE17 CH01 CH07 CH11 DA17

Claims (22)

[Claims] 1. A plurality of printing apparatuses are connected to each other so as to be able to exchange data with each other, and the plurality of printing apparatuses use first data conversion data as a reference for predetermined data conversion related to image processing. An image processing system including: a first printing device that holds the printing characteristics of the printing device; and a second printing device that does not hold the first data conversion data as the printing characteristics of the printing device. Then, in the second printing device, a conversion data acquisition unit that acquires second data conversion data for the predetermined data conversion in association with printing characteristics of the second printing device; and the first printing device. Get the first data conversion data from
The second data conversion data is corrected by correcting the second data conversion data so that the data conversion by the reference first data conversion data and the second data conversion data acquired by the conversion data acquisition unit has a predetermined conversion characteristic. An image processing system comprising: a correction unit that executes calibration. 2. A plurality of the first printing devices are connected to each other, and the plurality of the first printing devices hold the second data conversion data corresponding to the printing characteristics, respectively, and the correction means includes a plurality of the first printing devices. Of the printing devices, the first printing device that holds the second data conversion data having the conversion content closest in conversion content to the second data conversion data of the second printing device is determined, and the first printing device is determined.
The image processing system according to claim 1, wherein the first data conversion data is acquired from a printing device. 3. The image processing system according to claim 1, wherein the data conversion by the first data conversion data and the second data conversion data is a conversion in a table form. 4. The image processing system according to claim 1, wherein the predetermined data conversion is conversion of density level in print data. 5. The first data conversion data is the first data conversion data.
The image processing system according to claim 4, wherein a patch of a predetermined density level is printed on a sheet of paper by a printing device, and the density of the patch is obtained based on a result obtained by measuring the density of the patch by the density measuring device. . 6. The first and second printing devices are devices that form a toner image and transfer the toner image onto a sheet to perform printing, and the second data conversion data is the first or second printing device. 6. The image processing according to claim 5, wherein a toner patch image having a predetermined density level is formed on the transfer body in the printing device, and the density of the patch is obtained based on a result obtained by measuring with a sensor. system. 7. The image processing system according to claim 1, wherein the correction unit executes the calibration at a predetermined timing in the second printing apparatus. 8. The correction means corrects the second data conversion data based on a difference between a sensor reference value for measuring the concentration of the sensor and a measurement value of the sensor. The image processing system described in 1. 9. The image processing system according to claim 1, wherein the correction unit identifies the first printing device based on an identification symbol. 10. The image processing system according to claim 9, wherein the identification signal is a network address of the printing apparatus in a network. 11. A plurality of printing apparatuses are connected to each other so as to be able to exchange data with each other, and the plurality of printing apparatuses use first data conversion data as a reference for predetermined data conversion related to image processing. A first printing device held in correspondence with the printing characteristics of the printing device; and a second printing device not holding the first data conversion data as corresponding to the printing characteristics of the printing device
A calibration method in an image processing system including the printing device, wherein in the second printing device, the second data conversion data for the predetermined data conversion is made to correspond to the printing characteristics of the second printing device. To obtain the first data conversion data from the first printing device,
The second data conversion data is corrected by correcting the second data conversion data so that the data conversion by the reference first data conversion data and the second data conversion data acquired by the conversion data acquisition unit has a predetermined conversion characteristic. A calibration method comprising the step of executing a calibration. 12. A plurality of the first printing devices are connected to each other, and the plurality of the first printing devices respectively hold the second data conversion data corresponding to the printing characteristics, and the correction step includes a plurality of the first printing devices. Of the printing devices, the first printing device that holds the second data conversion data whose conversion content is closest to the second data conversion data of the second printing device is determined,
The calibration method according to claim 11, wherein the first data conversion data is acquired from the first printing device. 13. The first data conversion data and the second data
The data conversion by the data conversion data is a conversion in a table form.
The calibration method described in 2. 14. The calibration method according to claim 11, wherein the predetermined data conversion is conversion of a density level in print data. 15. The first data conversion data is based on a result obtained by printing a patch of a predetermined density level on a sheet in the first printing device and measuring the density of the patch with a density measuring device. 15. Obtained by
Calibration method described in. 16. The first and second printing devices are devices that form a toner image and transfer the toner image to a sheet to perform printing, and the second data conversion data is the first or second printing device. 16. The calibration according to claim 15, wherein a toner patch image of a predetermined density level is formed on the transfer body in the printing apparatus, and the density of the patch is obtained based on a result obtained by measuring with a sensor. Method. 17. The calibration method according to claim 11, wherein in the correction step, the calibration is executed at a predetermined timing in the second printing apparatus. 18. The correction step, wherein the second data conversion data is corrected based on a difference between a sensor reference value related to concentration measurement of the sensor and a measurement value of the sensor. Calibration method described in. 19. The calibration method according to claim 11, wherein the correcting step identifies the first printing device based on an identification symbol. 20. The calibration method according to claim 19, wherein the identification signal is a network address of the printing device in a network. 21. A program for a process executed by an information processing device, wherein the process connects a plurality of printing devices so that they can exchange data with each other, and the plurality of printing devices perform predetermined processing related to image processing. A first printing device that holds first data conversion data, which is a reference for data conversion of the above, in correspondence with the printing characteristics of the printing device, and the first data conversion data corresponds to the printing characteristics of the printing device. Calibration processing in an image processing system including a second printing device that does not hold the second printing device, the second printing device including the second data conversion data for the predetermined data conversion in the second printing device. To obtain the first data conversion data from the first printing device, corresponding to the printing characteristics of the device,
The second data conversion data is corrected by correcting the second data conversion data so that the data conversion by the reference first data conversion data and the second data conversion data acquired by the conversion data acquisition unit has a predetermined conversion characteristic. A program having steps for executing calibration. 22. A storage medium storing a program of a process to be executed by an information processing device, wherein the process connects a plurality of printing devices so that data can be exchanged with each other, and the plurality of printing devices: A first printing device that holds first data conversion data, which is a reference for predetermined data conversion related to image processing, in association with printing characteristics of the printing device, and the first data conversion data Calibration processing in an image processing system including a second printing device which is not held as corresponding to the printing characteristic of the second printing device, the second data conversion data for the predetermined data conversion in the second printing device. Corresponding to the printing characteristics of the second printing device, and obtains the first data conversion data from the first printing device,
The second data conversion data is corrected by correcting the second data conversion data so that the data conversion by the reference first data conversion data and the second data conversion data acquired by the conversion data acquisition unit has a predetermined conversion characteristic. A storage medium having a step of executing calibration.