JP2013201610A - Image processing apparatus, image forming apparatus, image processing system and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing apparatus which can generate a test image, for correcting the density while reducing the influence of in-plane unevenness, by a simple method.SOLUTION: A primary chart data generation unit 322 generates primary test image data. A secondary chart color conversion unit 370 calculates a measurement density value corresponding to a plurality of patches output onto a recording medium, from the read data of a primary test image. A correction necessity determination unit 342 calculates the difference between a value related to the measurement density value and a target density value corresponding to a correspondent patch. When the difference thus calculated is equal to or larger than a predetermined value, a secondary chart data generation unit 362 generates secondary test image data for each color of a patch corresponding to a difference equal to or larger than a predetermined value.

Description

  The present invention relates to an image processing apparatus, an image forming apparatus, an image processing system, and a program.

Patent Document 1 discloses an image processing apparatus that appropriately controls the execution of calibration according to the occurrence state of a partial toner low state.
Patent Document 2 discloses an image forming apparatus that uses a small number of recording materials and reduces the influence of distortion according to the position related to the main scanning direction of the density obtained by reading a patch image.
Patent Document 3 discloses an image processing apparatus that corrects density unevenness during transfer while suppressing the amount of processing required to create a gradation correction table and increasing the accuracy of ACC.
Patent Document 4 discloses an image processing apparatus capable of performing original image processing even in a controller unit.

JP 2010-249861 A JP 2011-059206 A JP 2010-171689 A Japanese Patent Laid-Open No. 08-009158

  An object of the present invention is to provide an image processing apparatus that can generate a test image for correcting a density by reducing the influence of in-plane unevenness by a simple method as compared with the case without this configuration. is there.

  The present invention according to claim 1 is a primary test image in which a plurality of first patch groups including one or a plurality of first patches formed in one color are arranged, and a plurality of colors are arranged in the main scanning direction. In order to form a primary test image on a recording medium so that there are a plurality of the first patch groups and a plurality of the first patch groups of a plurality of colors in the sub-scanning direction. Primary test image data generation means for generating primary test image data, and read data of the primary test image obtained by reading the primary test image formed on the recording medium, and output on the recording medium A measured density value calculating means for calculating a measured density value corresponding to the first patch included in the first patch group; a value relating to the calculated measured density value; and the corresponding first value. Difference calculating means for calculating a difference from the target density value corresponding to the patch, and the first difference corresponding to the difference equal to or greater than the predetermined value when the calculated difference is equal to or greater than the predetermined value. For each color of one patch, a secondary test image used for density correction in which a second patch group including a plurality of second patches formed in one color is arranged on a recording medium. An image processing apparatus includes secondary test image data generation means for generating secondary test image data for formation.

  According to a second aspect of the present invention, in the primary test image, the first patch group includes a plurality of patches formed at a plurality of different halftone dot densities, and has different colors in the main scanning direction. A plurality of the first patch groups are arranged, a plurality of the first patch groups having different colors in the sub-scanning direction are arranged, and a plurality of first patches constituting the primary test image are included in the secondary test image. A plurality of the second patches formed with a larger number of halftone dot densities than the number of halftone dot densities of the patches are arranged, and the second patches having different halftone dot densities in the main scanning direction are arranged. The image processing apparatus according to claim 1, wherein the second patches having different dot densities in the scanning direction are arranged.

  According to a third aspect of the present invention, each of the plurality of first patches arranged in the primary test image is formed with a plurality of halftone dot densities, and the measured density value calculating unit is configured to output the plurality of halftone dot densities. And calculating the difference between the value relating to the calculated measurement density value and the target density value corresponding to the halftone dot density of the corresponding first patch. The image processing apparatus according to Item 1.

  According to a fourth aspect of the present invention, there is provided a measured density representative value determining means for determining a representative value of the measured density for each of the plurality of halftone dots based on the measured density value calculated for each of the plurality of halftone dots. The difference calculation unit further includes a difference between the determined measured density representative value and a target density value corresponding to a halftone dot density of the corresponding first patch. An image processing apparatus.

  The present invention according to claim 5 further includes accepting means for accepting designation of an area from a user, wherein the measured density representative value determining means is the measured density value calculated for each of the plurality of halftone dot densities, The image processing apparatus according to claim 4, wherein the measured density of the first patch corresponding to the received area is determined as a representative value of the measured density corresponding to each of the plurality of halftone dot densities.

  According to a sixth aspect of the present invention, in the image processing apparatus according to the fifth aspect, the accepting unit accepts designation of a position in the main scanning direction or designation of a position in the sub-scanning direction from a user.

  The present invention according to claim 7 is characterized in that the secondary test image data generation unit is configured to use another halftone dot density in the vicinity of a halftone dot density in which the difference calculated by the difference calculation unit is greater than a predetermined value. 7. Secondary test image data for forming a secondary test image on a recording medium is generated so that a plurality of second patches formed with halftone dot densities are arranged at intervals smaller than The image processing apparatus according to any one of the above.

  In the present invention according to claim 8, the accepting unit accepts designation of a halftone dot density from a user, and the secondary test image data generating unit determines that the neighborhood of the designated halftone dot density is another The secondary test image data for forming a secondary test image on a recording medium is generated so that a plurality of second patches having dot densities formed at intervals smaller than the dot density are arranged. The image processing apparatus according to any one of 3 to 7.

  The present invention according to claim 9 is the image processing apparatus according to claim 1, further comprising in-plane unevenness correcting means for correcting in-plane unevenness based on the measured density value calculated by the measured density value calculating means. is there.

  The present invention according to claim 10 is a first patch comprising an image reading means for reading an image, an image forming means for forming an image on a recording medium, and one or a plurality of first patches formed in one color. A first test image in which a plurality of groups are arranged, the first patch group having a plurality of colors in the sub-scanning direction, the plurality of first patch groups having a plurality of colors in the main scanning direction; Primary test image data generating means for generating primary test image data for forming a primary test image arranged on the recording medium by the image forming means, and the primary test formed on the recording medium. Included in the first patch group that is output on a recording medium from read data of a primary test image obtained by reading an image by the image reading means. A measurement density value calculating unit that calculates a measurement density value corresponding to the first patch, a difference between a value related to the calculated measurement density value and a target density value corresponding to the corresponding first patch is calculated. Difference calculation means for performing, when the calculated difference is equal to or greater than a predetermined value, one color is formed for each color of the first patch corresponding to the difference equal to or greater than the predetermined value A secondary test image for forming a secondary test image used for density correction on a recording medium by the image forming means, in which a second patch group including a plurality of second patches is arranged. An image forming apparatus having secondary test image data generation means for generating data.

  The present invention according to claim 11 is a primary test in which a plurality of image forming means for forming an image on a recording medium and a plurality of first patch groups including one or a plurality of first patches formed in one color are arranged. An image is arranged so that there are a plurality of the first patch groups of a plurality of colors in the main scanning direction, and is arranged so that a plurality of the first patch groups of a plurality of colors exist in the sub-scanning direction. Obtained by reading the primary test image formed on the recording medium, and primary test image data generating means for generating primary test image data for forming the primary test image on the recording medium by the image forming means. A measured density value for calculating a measured density value corresponding to the first patch included in the first patch group output on the recording medium from the read data of the primary test image. Output means, difference calculating means for calculating a difference between the calculated value relating to the measured density value and the target density value corresponding to the corresponding first patch, and the calculated difference being determined in advance. A second patch group consisting of a plurality of second patches formed of one color for each color of the first patch corresponding to the difference greater than or equal to the predetermined value when the value is greater than or equal to the value; Image formation comprising secondary test image data generation means for generating secondary test image data for forming a secondary test image used for density correction on a recording medium by the image formation means Device.

  The present invention according to claim 12 includes an image reading device that reads an image, an image forming device that forms an image on a recording medium, and an image processing device, and the image processing device is formed in one color. A primary test image in which a plurality of first patch groups each composed of one or a plurality of first patches are arranged, arranged so that a plurality of the first patch groups of a plurality of colors exist in the main scanning direction; A primary test image for generating primary test image data for forming, on the recording medium, a primary test image arranged so that a plurality of first patch groups of a plurality of colors exist in the sub-scanning direction. From the read data of the primary test image obtained by the data generation means and the primary test image formed on the recording medium read by the image reading device, the recording medium A measured density value calculating means for calculating a measured density value corresponding to the first patch included in the first patch group outputted above; a value relating to the calculated measured density value; and the corresponding first value. A difference calculating means for calculating a difference from a target density value corresponding to one patch, and the difference corresponding to a difference greater than or equal to the predetermined value when the calculated difference is equal to or greater than a predetermined value. For each color of the first patch, a secondary test image used for density correction in which a second patch group composed of a plurality of second patches formed in one color is arranged is formed as the image. An image processing system having secondary test image data generation means for generating secondary test image data to be formed on a recording medium by an apparatus.

  According to a thirteenth aspect of the present invention, there is provided a primary test image in which a plurality of first patch groups including one or a plurality of first patches formed in one color are arranged, and a plurality of colors in the main scanning direction. For forming a primary test image on a recording medium in which a plurality of the first patch groups are arranged and a plurality of the first patch groups of a plurality of colors are present in the sub-scanning direction. A primary test image data generating step for generating primary test image data; and the first test image data output from the read data of the primary test image obtained by reading the primary test image formed on the recording medium. A measured density value calculating step for calculating a measured density value corresponding to a first patch included in one patch group; a value relating to the calculated measured density value; A difference calculating step for calculating a difference from a target density value corresponding to the first patch, and when the calculated difference is equal to or greater than a predetermined value, corresponds to a difference equal to or greater than the predetermined value. For each color of the first patch to be recorded, a secondary test image used for density correction is recorded in which a second patch group including a plurality of second patches formed in one color is arranged. An image processing program for causing a computer to execute a secondary test image data generation step for generating secondary test image data to be formed on a medium.

  According to the first aspect of the present invention, an image processing apparatus capable of generating a test image for correcting the density by reducing the influence of in-plane unevenness by a simple method as compared with the case without the present configuration. Can provide.

  According to the second aspect of the present invention, in addition to the effect obtained by the first aspect of the present invention, it is possible to generate a test image for performing density correction for each color or halftone density that requires density correction. An image processing apparatus can be provided.

  According to the third aspect of the present invention, in addition to the effect obtained by the first aspect of the present invention, it is possible to provide an image processing apparatus capable of correcting for each halftone dot density that needs density correction.

  According to the fourth aspect of the present invention, in addition to the effect obtained by the third aspect of the present invention, the density correction is performed by reducing the influence of in-plane unevenness as compared with the case where the present configuration is not provided. Therefore, it is possible to provide an image processing apparatus capable of generating a secondary test image.

  According to the present invention of claim 5, in addition to the effect obtained by the present invention of any one of claims 4, an image processing apparatus capable of preferentially correcting the density of a specified region can be provided.

  According to the sixth aspect of the present invention, in addition to the effect obtained by the fifth aspect of the present invention, an image processing apparatus capable of preferentially correcting the density of the position in the main scanning direction or the position in the sub-scanning direction is provided. it can.

  According to the present invention of claim 7, in addition to the effects obtained by the present invention of any one of claims 3 to 6, the halftone dot density that needs to be corrected is compared with the case where this configuration is not provided. And an image processing apparatus capable of correcting with high accuracy.

  According to the present invention of claim 8, in addition to the effect obtained by the present invention of any of claims 3 to 7, the specified halftone dot density is more accurate than the case without this configuration. It is possible to provide an image processing apparatus that can correct well.

  According to the present invention of claim 9, in addition to the effect obtained by the present invention of claim 1, an image processing apparatus capable of correcting in-plane unevenness when the in-plane unevenness is larger than a predetermined range. Can provide.

  According to the tenth aspect of the present invention, an image forming apparatus capable of generating a test image for density correction by reducing the influence of in-plane unevenness by a simple method as compared with the case without the present configuration. Can provide.

  According to the eleventh aspect of the present invention, as compared with the case where the present configuration is not provided, an image forming apparatus capable of generating a test image for density correction by reducing the influence of in-plane unevenness by a simple method. Can provide.

  According to the present invention of claim 12, an image processing system capable of generating a test image for correcting density by reducing the influence of in-plane unevenness by a simple method as compared with the case without this configuration. Can provide.

  According to the thirteenth aspect of the present invention, an image processing program capable of generating, by a simple method, a test image for correcting the density while reducing the influence of in-plane unevenness as compared with the case without the present configuration. Can provide.

1 is a diagram illustrating a configuration of an image forming apparatus. It is a figure which shows the hardware constitutions of an image processing apparatus. 2 is a block diagram showing an image processing program executed by the image processing apparatus. It is a figure which illustrates a primary chart. It is a figure which illustrates a primary chart density | concentration state screen. It is a figure which illustrates an in-plane nonuniformity warning screen. It is a figure which illustrates the graph which shows the difference of a target density value and a measured density representative value. It is a figure which illustrates a secondary chart. It is a figure which illustrates a secondary chart density state screen. It is a figure explaining calculation of correction | amendment LUT. It is a figure which shows an image processing system.

First, the configuration of the image forming apparatus 10 will be described.
FIG. 1 is a diagram illustrating the configuration of a tandem type image forming apparatus 10.
As shown in FIG. 1, the image forming apparatus 10 includes an image processing device 2, a communication device 13, an image forming unit 14, an intermediate transfer belt 16, a paper tray 17, a paper conveyance path 18, and a fixing device 19.
The image forming apparatus 10 of this example has only a printer function for printing image data received from a computer terminal connected via a network. However, the present invention is not limited to this. It may further have a function as a machine and a function as a facsimile.

First, the outline of the image forming apparatus 10 will be described. In the upper part of the image forming apparatus 10, an image processing apparatus 2, an image reading unit 12, and a communication apparatus 13 are arranged.
The image processing apparatus 2 is a controller provided with an arithmetic device, a memory, an ASIC, and the like, and controls other configurations of the image forming apparatus 10. The communication device 13 communicates with a computer terminal via a network.

  The image reading unit 12 includes a platen glass 124 on which a document is placed, a platen cover 122 that presses the document onto the platen glass 124, and an image reading device 130 that reads an image of the document placed on the platen glass 124. . The image reading apparatus 130 illuminates a document placed on the platen glass 124 with a light source 132, and reflects a reflected light image from the document into a full-rate mirror 134, a first half-rate mirror 135, and a second half-rate mirror. Scanning exposure is performed on an image reading element 138 made of a CCD or the like through a reduction optical system consisting of 136 and an imaging lens 137, and the color material reflected light image of the original is preliminarily determined by this image reading element 138. It is configured to read at (for example, 16 dots / mm).

The image processing apparatus 2 preliminarily performs shading correction, document position shift correction, gamma correction, frame deletion, color / movement editing, and the like on image data read by the image reading unit 12 or image data received from a computer terminal. Apply the prescribed image processing.
In this example, the color material reflected light image of the document read by the image reading unit 12 is, for example, document reflectivity data of three colors of red (R), green (G), and blue (B). By the image processing by the image processing apparatus 2, the original color material gradation data of four colors of yellow (Y), magenta (M), cyan (C), and black (K) is converted.

Below the image processing apparatus 2, a plurality of image forming units 14 are arranged corresponding to the colors constituting the color image. In this example, the first image forming unit 14K, the second image forming unit 14Y, and the third image forming corresponding to each color of black (K), yellow (Y), magenta (M), and cyan (C). The unit 14M and the fourth image forming unit 14C are arranged horizontally along the intermediate transfer belt 16 with a certain interval.
The intermediate transfer belt 16 rotates as an intermediate transfer member in the direction of the arrow A in the figure, and these four image forming units 14K, 14Y, 14M, and 14C are configured based on the image data input from the image processing apparatus 2 to each color. The toner images are sequentially formed and transferred (primary transfer) to the intermediate transfer belt 16 at a timing at which the plurality of toner images are superimposed on each other.
The order of the colors of the image forming units 14K, 14Y, 14M, and 14C is not limited to the order of black (K), yellow (Y), magenta (M), and cyan (C). ), Magenta (M), cyan (C), black (K), and the like.

The sheet conveyance path 18 is disposed below the intermediate transfer belt 16. The recording paper (recording medium) supplied from the paper tray 17 is transported on the paper transporting path 18, and the toner images of each color transferred onto the intermediate transfer belt 16 are transferred collectively (secondary transfer). The transferred toner image is fixed by the fixing unit 19 and discharged to the outside along the arrow B.
By providing the image reading unit 12 in the recording paper discharge unit, the image reading unit 12 is formed on the discharged recording paper without setting the recording paper discharged by the user in the image reading unit 12. The read image may be read.

Next, each configuration of the image forming apparatus 10 will be described in detail.
As shown in FIG. 1, when the image processing apparatus 2 receives image data from a computer terminal via the communication apparatus 13, the image processing apparatus 2 performs color conversion processing, density correction processing, halftone processing, and the like on the received image data. And output to the image forming unit 14.
Further, the image processing apparatus 2 generates test image data (primary chart, secondary chart) used for calibration as necessary, and generates the generated test image data (primary chart data, secondary chart data). Output to the image forming unit 14.

The first image forming unit 14K, the second image forming unit 14Y, the third image forming unit 14M, and the fourth image forming unit 14C are arranged and formed in parallel at a certain interval in the horizontal direction. The configuration is almost the same except that the color of the image is different. Accordingly, the first image forming unit 14K will be described below. The configuration of each image forming unit 14 is distinguished by adding K, Y, M, or C.
The image forming unit 14K forms an electrostatic latent image by the optical scanning device 140K that scans the laser light according to the image data input from the image processing device 2 and the laser light scanned by the optical scanning device 140K. And an image forming apparatus 150K.

The optical scanning device 140K modulates the semiconductor laser 142K according to the black (K) image data, and emits the laser light LB (K) from the semiconductor laser 142K according to the image data. The laser beam LB (K) emitted from the semiconductor laser 142K is applied to the rotary polygon mirror 146K via the first reflection mirror 143K and the second reflection mirror 144K, and is deflected and scanned by the rotation polygon mirror 146K. The light is irradiated onto the photosensitive drum 152K of the image forming apparatus 150K through the second reflecting mirror 144K, the third reflecting mirror 148K, and the fourth reflecting mirror 149K.
The image forming apparatus 150K includes a photosensitive drum 152K as an image carrier that rotates at a predetermined rotation speed in the direction of arrow A, and a charging unit that uniformly charges the surface of the photosensitive drum 152K. It comprises a scorotron 154K for primary charging, a developing device 156K for developing an electrostatic latent image formed on the photosensitive drum 152K, and a cleaning device 158K. The photosensitive drum 152K is uniformly charged by the scorotron 154K, and an electrostatic latent image is formed by the laser beam LB (K) irradiated by the optical scanning device 140K. The electrostatic latent image formed on the photosensitive drum 152K is developed with black (K) toner by the developing device 156K and transferred to the intermediate transfer belt 16. Residual toner, paper dust, and the like adhering to the photosensitive drum 152K after the toner image transfer process are removed by the cleaning device 158K.
The other image forming units 14Y, 14M, and 14C also form yellow (Y), magenta (M), and cyan (C) toner images in the same manner as described above, and intermediately transfer the formed toner images of the respective colors. Transfer to belt 16.

The intermediate transfer belt 16 has a constant tension between the drive roll 164, the first idle roll 165, the steering roll 166, the second idle roll 167, the backup roll 168, and the third idle roll 169. The drive roll 164 is rotationally driven by a drive motor (not shown), and is circulated at a predetermined speed in the direction of arrow A. The intermediate transfer belt 16 is formed into an endless belt by, for example, forming a flexible synthetic resin film such as polyimide in a belt shape and connecting both ends of the synthetic resin film formed in a belt shape by welding or the like. It has been done.
Further, the intermediate transfer belt 16 includes a first primary transfer roll 162K, a second primary transfer roll 162Y, a third primary transfer roll 162M, and a position facing the image forming units 14K, 14Y, 14M, and 14C, respectively. A fourth primary transfer roll 162C is provided, and the toner images of the respective colors formed on the photosensitive drums 152K, 152Y, 152M, and 152C are transferred onto the intermediate transfer belt 16 in a multiple manner by these primary transfer rolls 162. The The residual toner adhering to the intermediate transfer belt 16 is removed by a cleaning blade or brush of a belt cleaning device 189 provided downstream of the secondary transfer position.

In the paper transport path 18, a paper feed roller 181 for taking out the recording paper from the paper tray 17, a first roller pair 182 and a second roller pair 183 for paper transport, and a secondary transfer of the recording paper at a predetermined timing. A resist roll 184 that is transported to a position is disposed.
In addition, a secondary transfer roll 185 that is in pressure contact with the backup roll 168 is disposed at the secondary transfer position on the paper transport path 18, and each color toner image transferred onto the intermediate transfer belt 16 is Secondary transfer is performed on the recording paper by the pressing force and electrostatic force of the secondary transfer roll 185. The recording paper on which the toner images of the respective colors are transferred is conveyed to the fixing device 19 by the first conveying belt 186 and the second conveying belt 187.
The fixing device 19 melts and fixes the toner to the recording paper by performing heat treatment and pressure treatment on the recording paper on which the toner images of the respective colors are transferred.

FIG. 2 is a diagram illustrating a hardware configuration of the image processing apparatus 2.
As shown in FIG. 2, the image processing apparatus 2 includes a control device 260 including a calculation unit 262 such as a CPU and a storage unit 264 such as a memory, a communication device 270, a recording device 272, a user interface device (UI device). ) 280.
That is, the image processing apparatus 2 has a hardware configuration part as a computer capable of information processing and communication with other processing apparatuses or terminals.
In the following drawings, substantially the same components and processes are denoted by the same reference numerals.
The UI device 280 includes a display device such as an LCD (Liquid Crystal Display) display device or a CRT (Cathode Ray Tube) display device, and a keyboard / touch panel.

Next, a program installed in the image processing apparatus 2 will be described.
FIG. 3 is a block diagram showing an image processing program 30 installed in the image processing apparatus 2 and executed by the image processing apparatus 2.
For example, the image processing program 30 is supplied to the image processing apparatus 2 via a storage medium or the like, stored in the storage unit 264, and installed on the image processing apparatus 2 on the image processing apparatus 2. It is executed by specifically utilizing the hardware resources of
In this example, the entire functional configuration of the program is installed in the image processing apparatus 2 as software. However, the present invention is not limited to this. For example, a part of the program is realized by hardware such as an ASIC. Also good.
The program installed in the image processing apparatus 2 is recorded on a storage medium such as a CD-ROM, and may be installed in the image processing apparatus 2 via this storage medium, or distributed in the form of a data signal, It may be installed in the image processing apparatus 2.

As shown in FIG. 3, the image processing program 30 includes a condition receiving unit 310, a primary chart processing unit 32, a secondary chart processing unit 36, an image data receiving unit 400, a color conversion unit 402, a correction processing unit 404, and a print control unit. 410.
The primary chart processing unit 32 performs processing related to a primary chart, which will be described later with reference to FIG. 4, and includes a primary chart data generation unit 322, a primary chart information storage unit 324, a primary chart print control unit 326, a primary chart reading information reception unit 328, A primary chart color conversion unit 330, a primary state display unit 332, a primary unevenness determination unit 334, a primary unevenness correction unit 336, a primary measurement density representative value determination unit 340, and a correction necessity determination unit 342 are configured.
The secondary chart processing unit 36 performs processing related to the secondary chart, which will be described later with reference to FIG. 8, and includes a secondary chart data generation unit 362, a secondary chart information storage unit 364, a secondary chart print control unit 366, and a secondary chart. Reading information reception unit 368, secondary chart color conversion unit 370, secondary state display unit 372, secondary unevenness determination unit 374, secondary unevenness correction unit 376, secondary measurement density representative value determination unit 380, and correction LUT (Look up Table) calculation unit 382.
The primary chart and the secondary chart are test images (calibration charts) that are used to correct the density when image data is formed on a recording medium.
Further, in this embodiment, after the primary chart (primary test image) is measured, the correction LUT (correction table) is not calculated, and the secondary chart (secondary test image) is printed. In use, a correction LUT is calculated.

The condition receiving unit 310 receives information (condition information) indicating a condition input by the user operating the UI device 280.
The condition information indicates conditions regarding correction (calibration) for the color of the image formed on the recording medium desired by the user, and includes a designated color, a designated area, and a designated coverage.
Here, the coverage is the halftone dot area ratio or the halftone dot density, and in the halftone process, the coverage is high for a portion where the density is high in the image data to be printed, and the portion where the density is low. Reduces the coverage and forms an image on the recording medium.

The primary chart information storage unit 324 stores data (primary chart data) for forming a primary chart on a recording medium.
The primary chart data includes position information, color information (CMYK) at the position indicated by the position information, and coverage.
Here, the coverage takes any value of c1 to c8 (c1 <c2 <... <C8), as will be described later.
The primary chart data generation unit 322 reads the primary chart data from the primary chart information storage unit 324 and outputs the primary chart data to the primary chart print control unit 326.

FIG. 4 is a diagram illustrating a primary chart.
FIG. 4A is a diagram illustrating the overall configuration of the primary chart.
The primary chart is divided into, for example, 4 × 4 in the recording medium, and a patch set (patch group) C formed of cyan (C), magenta (M), yellow (Y), and black (K) in each divided area. (1) to (4), M (1) to (4), Y (1) to (4), and K (1) to (4) are arranged.
In this embodiment, the primary chart is divided into 4 × 4, but any N × M (N and M are integers of 1 or more. However, N and M are always the same number. (The same applies to the secondary chart described later).
One set of patches of each color is arranged at each of positions 1 to 4 in the horizontal direction (main scanning direction). Furthermore, the patch sets of the respective colors are arranged so that the positions in the vertical direction are different in the horizontal positions 1 to 4.
For example, the patch set C (1) is arranged at (horizontal position 1, vertical position 1), the patch set C (2) is arranged at (horizontal position 2, vertical position 2), and the patch set C (3) is ( The patch set C (41) is arranged at (horizontal position 4, vertical position 4).
As described above, the patch sets of the respective colors are arranged in the horizontal positions and the vertical positions, so that the influence of the in-plane unevenness only on the patch sets of a specific color is reduced.

Furthermore, as illustrated in FIG. 4B, each patch set is divided into, for example, eight patches.
Each patch has a different coverage (halftone dot density, halftone dot area ratio) c1 to c8 (c1 <c2 <... <C8).
For example, c1 = 0% (white), c2 = 20%, c3 = 40%, c4 = 50%, c5 = 60%, c6 = 70%, c7 = 80%, c8 = 100% (solid, maximum density) It is.
Further, as shown in FIG. 4B, the coverage arrangement of each patch is different for each horizontal position (for each patch set).
For example, as illustrated in FIG. 4B, in the patch set C (1), the coverage of the upper left patch e1 is c1, whereas in the patch set C (2), the coverage of the upper left patch e1 is c5.
In this way, by arranging the patches of each coverage differently in each patch set, it is reduced that the influence of the in-plane unevenness is exerted only on the patches of a specific coverage.

When the condition receiving unit 310 does not receive the designation of coverage from the user, the values of the coverages c1 to c8 of each patch may be predetermined values (for example, the values in the above example).
On the other hand, when the condition receiving unit 310 receives a coverage specification from the user, the specified coverage value may be set to any one of c1 to c8.
The patch coverage may be the same for all CMYK colors, or may be different for each CMYK color.

For example, when c4 = 50% in a cyan (C) patch set, c4 = 50% or c4 = 40% may be used in a black (K) patch set.
In this case, the condition receiving unit 310 may specify whether the patch coverage is the same for all CMYK colors or different for each CMYK color.
Further, when the patch coverage is the same for all the colors of CMYK, c1 to c8 may be specified values, and when different for each color of CMYK, the user sets the values of c1 to c8. You may specify what percentage each.
However, c8 = 100% may be set for all colors for maximum density correction described later.
In this way, the primary chart is not provided for each area, and patches formed by CMYK colors and coverages c1 to c8 are arranged in the horizontal positions 1 to 4, respectively. In the primary chart, the influence of in-plane unevenness is reduced.

The primary chart print control unit 326 (FIG. 3) controls the image forming unit 14 to print the primary chart data from the primary chart data generation unit 322 on a recording medium.
The primary chart reading information reception unit 328 receives primary chart reading information obtained by the image reading unit 12 reading the primary chart formed on the recording medium, and outputs the primary chart reading information to the primary chart color conversion unit 330.
The primary chart read information indicates pixel values (luminance, brightness, density, etc.) of red (R), green (G), and blue (B) for each pixel.

The primary chart color conversion unit 330 converts the pixel values indicated by red (R), green (G), and blue (B) into density values (tone values) for each of CMYK using a conversion table (color conversion profile). ) To generate primary chart measurement data.
The primary chart measurement data includes position information, color information (CMYK) of the position indicated by the position information, and a density value (measured density value).
In other words, the primary chart color conversion unit 330 calculates a measured density value corresponding to each patch formed on the primary chart from the primary chart reading information.
Further, the primary chart color conversion unit 330 outputs the primary chart measurement data to the primary state display unit 332.

The primary state display unit 332 causes the UI device 280 to display a primary chart density state screen from the primary chart data stored in the primary chart information storage unit 324 and the primary chart measurement data from the primary chart color conversion unit 330.
FIG. 5 is a diagram illustrating a primary chart concentration state screen. The primary chart density state screen is displayed as a separate screen for each color of CMYK.
As illustrated in FIG. 5, in the primary chart density state screen, for each color of CMYK, the coverages c1 to c8 of the patches in the horizontal positions 1 to 4 and the respective patch sets of the primary chart arranged in the horizontal positions. The relationship with the measured density value corresponding to each is shown.
The measured density value (and a target density value to be described later) takes a value of, for example, 0 to 1023, and becomes the maximum density (solid density) when the density value is 1023.

The primary state display unit 332 (FIG. 3) collates the position information and color information of the primary chart data with the position information and color information of the primary chart measurement data, and displays them in the primary chart data for each color of CMYK. A density value (measured density value) corresponding to each of the coverages c1 to c8 is determined.
Furthermore, the primary state display unit 332 plots the relationship between the horizontal positions 1 to 4 and the corresponding density values (measured density values) for each of the coverages c1 to c8.
For example, point A of “measured density value corresponding to c1” in FIG. 5 indicates a measured density value obtained by reading a patch whose coverage is c1 in the patch set at the horizontal position 1.

The primary unevenness determination unit 334 determines whether or not in-plane unevenness exceeding an allowable range has occurred in each of the coverages c1 to c8 from the measured density value displayed on the primary chart concentration state screen.
Specifically, the primary unevenness determination unit 334 calculates the difference between the maximum value and the minimum value of the measured density values in each of the coverages c1 to c8, and the difference is equal to or greater than a predetermined threshold value α. Then, it is determined that the in-plane unevenness exceeding the allowable range occurs in the coverage.
Instead, the primary unevenness determination unit 334 calculates the standard deviation of the measured density value in each of the coverages c1 to c8, and when the standard deviation is equal to or greater than a predetermined threshold, the allowable range in the coverage It may be determined that the above in-plane unevenness has occurred (the same applies to the secondary unevenness determination unit 374 described later).
Further, the primary unevenness determination unit 334 displays “NG” for the coverage determined to have an in-plane unevenness exceeding the allowable range on the primary chart density state screen, and the in-plane unevenness exceeding the allowable range is generated. “OK” is displayed for coverages determined not to be performed.
Even when the difference between the maximum value and the minimum value of the measured density value is smaller than the threshold value α, the in-plane unevenness is not completely absent in the coverage. If it is greater than or equal to the threshold value α, it will be affected by in-plane unevenness in the processing for the primary chart and the processing for the secondary chart described later, and hence the subsequent unevenness correction processing is performed (also in the secondary chart processing unit 36). The same).

When the primary unevenness determination unit 334 determines that in-plane unevenness has occurred in one or more coverages, the primary unevenness warning screen illustrated in FIG. 6 is displayed on the UI device 280.
FIG. 6 is a diagram illustrating an in-plane unevenness warning screen.
The in-plane unevenness warning screen displays the coverage where the in-plane unevenness has occurred.
In addition, on the in-plane unevenness warning screen, a “YES” button and a “NO” button are displayed that allow the user to determine whether or not to continue the process. When the user presses the “YES” button, When the process by the primary unevenness correction unit 336 is performed and the user presses the “NO” button, the process ends.

The primary unevenness correction unit 336 (FIG. 3) performs unevenness correction processing when the user presses the “YES” button on the in-plane unevenness warning screen.
Specifically, the primary unevenness correction unit 336 performs unevenness correction processing, for example, by adjusting the exposure amount of the photosensitive drum 152 by the laser light scanned from the optical scanning device 140.
Further, the primary unevenness correction unit 336 may perform maximum density correction processing as necessary.
When the unevenness correction is performed, the primary chart processing unit 32 may generate a primary chart again, read the generated primary chart, and generate primary chart measurement data.
In this case, the primary measurement density representative value determination unit 340 performs processing on the primary chart measurement data generated again.

The primary measurement density representative value determination unit 340 determines a representative value for each of the coverages c1 to c8 from the measurement density values corresponding to the coverages c1 to c8, and the determined representative value is determined to the correction necessity determination unit 342. Output.
Specifically, in the condition receiving unit 310, when the designated area is not received from the user, the primary measurement concentration representative value determination unit 340 calculates the average value of the measured concentration for each of the coverages c1 to c8 as the representative value. And decide.
For example, in the example of FIG. 5, the primary measurement density representative value determination unit 340 calculates the average value of the measurement density at the horizontal positions 1 to 4 for the coverage c1, and uses the calculated average value as the representative value of the coverage c1. decide.
Further, the primary measurement density representative value determination unit 340 similarly calculates the average value of the measured density at the horizontal positions 1 to 4 for each of the coverages c2 to c8, and calculates the calculated average value for each of the coverages c2 to c8. Determined as a representative value.

On the other hand, when the condition receiving unit 310 receives the designated area from the user, the primary measurement density representative value determining unit 340 determines the measured density in the designated area as the representative value for each of the coverages c1 to c8.
For example, when the user designates “horizontal position 4”, in the example of FIG. 5, the primary measurement density representative value determination unit 340 determines the measurement density at the horizontal position 4 as the representative value of the coverage c1 for the coverage c1. To do.
Further, the primary measurement density representative value determination unit 340 similarly determines the measurement density at the lateral position 4 as the representative value of each of the coverages c2 to c8 for each of the coverages c2 to c8.
Although the primary measurement concentration representative value determination unit 340 determines the average value of the measurement concentrations as the representative value, for example, the median value of the measurement concentrations may be determined as the representative value (secondary measurement concentration representative value described later). The same applies to the determination unit 380).

The correction necessity determination unit 342 determines whether density correction is necessary for each color and each of the coverages c1 to c8, using the representative value determined by the primary measurement density representative value determination unit 340. To do.
FIG. 7 is a diagram illustrating a graph showing the difference between the target density value and the measured density representative value.
In FIG. 7, the target density value is indicated by a broken line, and the measured density representative value is indicated by a solid line.
A target density value is set for each of the coverages c1 to c8 of each color of CMYK, and the target density value is stored in the primary chart information storage unit 324 in association with each coverage.
The target density value may be set for each 1% coverage, for example, for each coverage of 0 to 100%, but is a predetermined value (coverage when the specified coverage is not received by the condition receiving unit 310). It may be set only for.
In this case, when the target density value is not set for the specified coverage received by the condition receiving unit 310, the correction necessity determination unit 342 uses the set adjacent data (target density value). The calculation may be performed by linear interpolation.

The correction necessity determination unit 342 calculates a difference ΔDen between the target density value and the measured density representative value for each coverage for each color.
Further, the correction necessity determination unit 342 determines whether or not the difference ΔDen exceeds the threshold value β. If ΔDen> β, it is determined that density correction is necessary for the coverage.
For example, in the example of FIG. 7, if the difference ΔDen5 between the measured density representative value D5 and the target density value d5 of the cyan (C) coverage c5 (for example, 60%) exceeds the threshold value β, whether correction is necessary or not. The determination unit 342 determines that “cyan (C) coverage c5 (60%) requires density correction”.
Further, the correction necessity determination unit 342 outputs the determination result to the secondary chart data generation unit 362.
In this embodiment, since the necessity of density correction is determined using the representative value of each coverage, the influence of in-plane unevenness is reduced when the secondary chart is generated.
Furthermore, by making the measured density of the designated area a representative value, when the density of the designated area needs to be corrected, the density of the designated area is preferentially corrected.

The secondary chart data generation unit 362 (FIG. 3) uses the determination result from the correction necessity determination unit 342 to generate data (secondary chart data) for forming a secondary chart on the recording medium. The data is output to the next chart print control unit 366 and the secondary chart information storage unit 364.
The secondary chart information storage unit 364 stores the secondary chart data generated by the secondary chart data generation unit 362.
The secondary chart data includes position information, position color information (CMYK) indicated by the position information, and coverage (C1 to C32).

FIG. 8 is a diagram illustrating a secondary chart.
FIG. 8A is a diagram illustrating the overall configuration of the secondary chart.
The secondary chart is divided into, for example, 4 × 4 on the recording medium, and patch sets P (11) to P (44) formed in one color are arranged in each divided region.
Here, the primary chart has a set of patches formed by all colors of CMYK, whereas the secondary chart has a set of patches formed by only one color (for example, cyan (C)). ing.

The secondary chart data generation unit 362 generates a secondary chart formed with a color determined to require density correction in any coverage in the determination result by the correction necessity determination unit 342.
For example, when the correction necessity determination unit 342 determines that “cyan (C) coverage c5 (60%) requires density correction”, the secondary chart data generation unit 362 is formed using only cyan (C). A secondary chart in which the patch set is arranged is generated.
If a color is specified in the condition receiving unit 310, the secondary chart data generation unit 362 also generates a secondary chart formed with the specified color.

In the primary chart, the patches in the patch set are formed with coverages c1 to c8 (c1 <c2 <... <C8), respectively. In the secondary chart, the patches in the patch set are , C1 to C32 (C1 <C2 <... <C32). Here, C1 = 0% and C32 = 100% may be used.
Specifically, as in the primary chart, in the secondary chart, each patch set is divided into, for example, 8 patches.
As shown in FIGS. 8A and 8B, the patch sets P (11), P (22), P (33), and P (44) are eight patches formed by the coverages C25 to C32, respectively. including.
Further, as shown in FIGS. 8A and 8B, the patch sets P (12), P (23), P (34), and P (41) are each formed by the coverages C17 to C24. Including patches.
Further, as shown in FIGS. 8A and 8B, the patch sets P (13), P (24), P (31), and P (42) are formed by the coverages C9 to C16, respectively. Including patches.
Further, as shown in FIGS. 8A and 8B, the patch sets P (14), P (21), P (32), and P (43) are each formed by coverages C1 to C8. Including patches.

Further, as shown in FIG. 8B, even if the coverage range (for example, C25 to C32) is the same patch set, the coverage arrangement of each patch is different for each horizontal position (each patch set). It has become.
For example, as illustrated in FIG. 8B, in the patch set P (11), the coverage of the upper left patch E1 is C32, but in the patch set P (11), the coverage of the upper left patch E1 is C25.

Further, although C1 = 0% and C32 = 100%, the coverage of C2 to C31 is determined by the secondary chart data generation unit 362.
Specifically, the secondary chart data generation unit 362 determines the vicinity of the coverage in which the density correction is required in the determination result by the correction necessity determination unit 342 (for example, a range such as 10% above and below the coverage). Coverage should be allocated at smaller intervals than other coverages.
For example, when it is determined that “cyan (C) coverage c5 (60%) requires density correction”, when creating a cyan (C) secondary chart, the secondary chart data generation unit 362 may, for example, C17 = 57%, C18 = 58%, C19 = 59%, C20 = 60%, C21 = 61% for patches of the patch set P (12), P (23), P (34), P (41) Coverage is determined every 1%, such as C22 = 62%, C23 = 63%, and C24 = 64%.

On the other hand, for other coverages, the secondary chart data generation unit 362 determines the coverage for each value larger than 1%.
For example, C25 = 65%, C26 = 67%, C27 = 80%, C28 = 82%, C29 = 85 for patches of the patch set P (11), P (22), P (33), P (44). %, C30 = 87%, C31 = 90%, and C32 = 100%.
Further, for example, C9 = 37%, C10 = 40%, C11 = 42%, C12 = 45%, C13 for patches of the patch set P (13), P (24), P (31), P (42). = 47%, C14 = 50%, C15 = 52%, C16 = 55%.
Also, for example, C1 = 0%, C2 = 5%, C3 = 10%, C4 = 15%, C5 for patches in the patch set P (14), P (21), P (32), P (43) = 20%, C6 = 25%, C7 = 30%, C8 = 35%.

Note that the coverage range in which the interval is reduced may be appropriately changed according to the coverage value for which density correction is required.
For example, when the coverage value for which density correction is required is 5%, it may be finely set in the range of 0% to 20%.
Further, when the coverage is specified in the condition reception unit 310, the secondary chart data generation unit 362 may generate secondary chart data by finely setting the coverage even in the vicinity of the specified coverage.
Further, as described above, the secondary chart is not provided for each region, and the patches formed by the respective coverages C1 to C32 are arranged at the respective horizontal positions 1 to 4, so that one sheet is provided. In the secondary chart, the influence of in-plane unevenness is reduced.

The secondary chart print control unit 366 (FIG. 3) controls the image forming unit 14 to print the secondary chart data from the secondary chart data generation unit 362 on the recording medium.
The secondary chart reading information receiving unit 368 receives secondary chart reading information obtained by the image reading unit 12 reading the secondary chart formed on the recording medium, and outputs the secondary chart reading information to the secondary chart color conversion unit 370. To do.
The secondary chart color conversion unit 370 uses the conversion table (color conversion profile) to convert the pixel values indicated by red (R), green (G), and blue (B) into respective density values (tones). Value) to generate secondary chart measurement data and output it to the secondary state display unit 372.
The secondary chart measurement data includes position information, color information (CMYK) of the position indicated by the position information, and a density value (measured density value).
In other words, the secondary chart color conversion unit 370 calculates a measured density value corresponding to each patch formed on the secondary chart from the secondary chart reading information.

The secondary state display unit 372 displays a secondary chart density state screen from the secondary chart data stored in the secondary chart information storage unit 364 and the secondary chart measurement data from the secondary chart color conversion unit 370. It is displayed on the device 280.
FIG. 9 is a diagram illustrating a secondary chart density state screen. The secondary chart density state screen is displayed separately for each color of CMYK.
As illustrated in FIG. 9, on the secondary chart density state screen, for each color of CMYK, the coverage C1 of the patches in the horizontal positions 1 to 4 and each patch set of the secondary chart arranged in each horizontal position. The relationship with measured density values corresponding to .about.C32 is shown.
The secondary state display unit 372 (FIG. 3) collates the position information and color information of the secondary chart data with the position information and color information of the secondary chart measurement data, respectively, for each color of CMYK. A density value (measured density value) corresponding to each of the coverages C1 to C32 indicated in the data is determined.
Further, the secondary state display unit 372 plots the relationship between the horizontal positions 1 to 4 and the corresponding density values (measured density values) for each of the coverages C1 to C32.

The secondary unevenness determination unit 374 determines whether or not in-plane unevenness exceeding the allowable range occurs in each of the coverages C1 to C32 from the measured density value displayed on the secondary chart density state screen.
Specifically, the secondary unevenness determination unit 374 calculates the difference between the maximum value and the minimum value of the measured density values in each of the coverages C1 to C32, and the difference is equal to or greater than a predetermined threshold value α. In addition, it is determined that in-plane unevenness exceeding the allowable range occurs in the coverage.
Further, the secondary unevenness determination unit 374 displays “NG” for the coverage determined to have an in-plane unevenness exceeding the allowable range on the secondary chart density state screen, and the in-plane unevenness exceeding the allowable range is displayed. “OK” is displayed for the coverage that is determined not to occur.
In addition, the secondary unevenness determination unit 374 causes the UI device 280 to display an in-plane unevenness warning screen, similar to the primary unevenness determination unit 334.
Similar to the primary unevenness correction unit 336, the secondary unevenness correction unit 376 performs unevenness correction processing when the user presses the “YES” button on the in-plane unevenness warning screen.

The secondary measurement density representative value determination unit 380 determines a representative value for each of the coverages C1 to C32 from the measurement density values corresponding to the coverages C1 to C32, and the determined representative value is determined to the correction necessity determination unit 342. Output.
Specifically, in the condition reception unit 310, when the designated area is not received from the user, the secondary measurement density representative value determination unit 380 displays the average value of the measurement density for each of the coverages C1 to C32 as a representative. Determine with value.
For example, in the example of FIG. 9, the secondary measurement density representative value determination unit 380 calculates the average value of the measurement density at the horizontal positions 1 to 4 for the coverage C1, and uses the calculated average value as the representative value of the coverage C1. And decide.
Furthermore, the secondary measurement density representative value determination unit 380 similarly calculates the average value of the measured density at the horizontal positions 1 to 4 for each of the coverages C2 to C32, and calculates the calculated average value for each of the coverages C2 to C32. Is determined to be a representative value.

On the other hand, when the condition receiving unit 310 receives the designated area from the user, the secondary measurement density representative value determining unit 380 determines the measured density in the designated area as the representative value for each of the coverages C1 to C32. .
For example, when the user designates “horizontal position 4”, in the example of FIG. 9, the secondary measurement density representative value determination unit 380 uses the measurement density at the horizontal position 4 as the representative value of the coverage C1 for the coverage C1. decide.
Further, the secondary measurement density representative value determination unit 380 similarly determines the measurement density at the lateral position 4 as the representative value of each of the coverages C2 to C32 for each of the coverages C2 to C32.

The correction LUT calculation unit 382 calculates a correction LUT for each color using the representative value determined by the secondary measurement density representative value determination unit 380.
Specifically, the correction LUT calculation unit 382 calculates the correction LUT as illustrated in FIG.
10A and 10B are diagrams for explaining the calculation of the correction LUT. FIG. 10A is a graph illustrating the difference between the target density value and the measured density representative value, and FIG. 10B is a diagram illustrating the correction curve. In FIG. 10A, the target density value is indicated by a broken line, and the measured density representative value is indicated by a solid line.
A target density value is set for each of the coverages C1 to C32 of each color of CMYK, and this target density value is associated with each coverage to obtain a secondary chart information storage unit 364 (or a primary chart information storage unit 324). ) Is stored.

Further, when the coverage formed in the primary chart is not formed in the secondary chart (for example, when c2 = 5% in the primary chart and there is no patch of coverage 5% in the secondary chart), the primary chart The coverage formed in step 1 and the corresponding measured concentration value may be used.
At this time, since the timing at which the primary chart is printed and the timing at which the secondary chart is printed are different, the density difference between jobs may be taken into consideration.
The correction LUT calculation unit 382 calculates the difference between the target density value and the measured density representative value shown in FIG. 10A. When the target density value is set as the input density value, the calculated difference is corrected. The correction curve (drawing LUT) shown in FIG. 10B is generated so that the output density value becomes the same.
In addition, about the point between the target density values corresponding to coverage C1-C32, a calculation may be made by interpolating by linear interpolation etc., for example.
In this embodiment, since the density is corrected using the representative value of each coverage, the density is corrected while reducing the influence of in-plane unevenness.
Furthermore, by making the measured density of the designated area a representative value, when the density of the designated area needs to be corrected, the density of the designated area is preferentially corrected.

The image data receiving unit 400 (FIG. 3) receives image data from a computer terminal or the like.
The color conversion unit 402 converts the pixel values indicated by red (R), green (G), and blue (B) of the received image data into respective density values (CMYK) using a conversion table (color conversion profile). (Gradation value).
The correction processing unit 404 calculates an output density value from the correction curve generated by the correction LUT calculation unit 382 using the converted density value as an input density value.
The print control unit 410 performs halftone processing on the calculated output density value, and further causes the image forming unit 14 to print the density-corrected and halftone-processed image data on a recording medium. Control.

In the above-described embodiment, the image processing apparatus 2 incorporated in the image forming apparatus 1 executes the image processing program 30. However, the image processing apparatus connected to the image forming apparatus via a network performs image processing. The program 30 may be executed.
FIG. 11 is a diagram illustrating the image processing system 100.
The image forming apparatus 10A, the image reading apparatus 12A, the computer terminal 102, and the image processing apparatus 2A are connected via a network.

The image forming apparatus 10A has substantially the same configuration as the image forming unit 14 of the image forming apparatus 10 shown in FIG.
The image reading device 12A has substantially the same configuration as the image reading unit 12 shown in FIG. Note that the image reading apparatus 12A may include, for example, an inline sensor attached to the inside of the image forming apparatus 10A, an external colorimeter, or the like.
The computer terminal 102 transmits the image data to the image processing apparatus 2A.

The image processing apparatus 2A is a print server, for example, and has substantially the same configuration as the image processing apparatus 2 shown in FIG.
Further, the image processing apparatus 2A executes the image processing program 30 shown in FIG.
The image processing apparatus 2A performs necessary processing on the image data received from the computer terminal 102 and transmits the image data to the image forming apparatus 10A.
The image forming apparatus 10A forms the image data received from the image processing apparatus 2A on a recording medium.
The image processing apparatus 2A causes the image forming apparatus 10A to form a primary chart and a secondary chart, and the image reading apparatus 12A reads the formed primary chart and secondary chart, and the obtained read data is read by the image processing apparatus 2A. The image processing apparatus 2A may process the read data.

Although the number of patches in the patch set is eight, the number of patches can be increased or decreased as long as the size of the patch whose position and density can be measured is satisfied.
The coverage in the primary chart is eight values c1 to c8, but can be changed as appropriate according to the increase or decrease in the number of patches.
Similarly, the coverage in the secondary chart is 32 values C1 to C32. However, the coverage can be appropriately changed according to increase / decrease of the number of colors, the number of patch sets, and the number of patches.

In the primary chart and the secondary chart, patches are formed in the patch set. However, each patch does not necessarily have to be assembled as a patch set.
In other words, in each region (lateral position), each patch may be randomly arranged regardless of its color and coverage.
That is, in the case of the primary chart, if patches of all colors (CMYK) and all coverages (c1 to c8) are arranged in each area, the arrangement of patches in each area may be random. Good.
In the case of the secondary chart, as long as patches of all the coverages (C1 to C32) are arranged in each area, the arrangement of patches in each area may be random.
For example, in the primary chart, when the color of a patch is cyan and the coverage is c = 1 (0%), the color of the patch adjacent to the patch is magenta and the coverage is c = 8 (100%). It may be.
For example, in the secondary chart, when the coverage of a certain patch is C = 1 (0%), the coverage of a patch adjacent to the patch may be C = 32 (100%).

In the above-described embodiment, the condition receiving unit 310 receives the horizontal position (position in the main scanning direction) as the area designation, but may receive the vertical position (position in the sub scanning direction).
In this case, the processing performed for each horizontal position in the image processing program 30 described above may be performed for each vertical position.
For example, the primary state display unit 332 (and the secondary state display unit 372) correspond to the coverage of patches in each patch set of the vertical position and the primary chart (or secondary chart) arranged in each vertical position. The relationship with the measured density value to be displayed may be displayed.
Further, for example, the primary measurement density representative value determination unit 340 (and the secondary measurement density representative value determination unit 380) may determine the measurement density at the designated vertical position as the representative value for each coverage.

10: Image forming apparatus,
2 ... Image processing device,
30: Image processing program,
310 ... Condition receiving part,
32 ... primary chart processing unit,
322 ... Primary chart data generation unit,
324 ... Primary chart information storage unit,
326... Primary chart printing control unit,
328... Primary chart reading information receiving unit,
330 ... primary chart color conversion unit,
332 ... Primary state display section,
334 ... primary unevenness determination unit,
336 ... primary unevenness correction unit,
340 ... primary measurement concentration representative value determination unit,
342 ... correction necessity determination unit,
36 ... secondary chart processing unit,
362 ... Secondary chart data generation unit,
364 ... Secondary chart information storage unit,
366 ... secondary chart printing control unit,
368 ... Secondary chart reading information receiving unit,
370 ... secondary chart color conversion unit,
372 ... Secondary state display section,
374 ... secondary unevenness determination unit,
376 ... secondary unevenness correction unit,
380 ... Secondary measurement concentration representative value determining unit,
382 ... Correction LUT calculation unit,
400: Image data receiving unit,
402: Color conversion unit,
404... Correction processing unit,
410... Print control unit,

Claims (13)

A primary test image in which a plurality of first patch groups including one or a plurality of first patches formed in one color are arranged, and a plurality of the first patch groups of a plurality of colors are arranged in the main scanning direction. Primary that generates primary test image data for forming, on a recording medium, primary test images that are arranged to exist and are arranged so that a plurality of the first patch groups of a plurality of colors exist in the sub-scanning direction. Test image data generating means;
Measurement corresponding to the first patch included in the first patch group output on the recording medium from the read data of the primary test image obtained by reading the primary test image formed on the recording medium A measured concentration value calculating means for calculating a concentration value;
Difference calculating means for calculating a difference between the calculated value relating to the measured density value and a target density value corresponding to the corresponding first patch;
When the calculated difference is equal to or greater than a predetermined value, a plurality of second colors formed with one color for each color of the first patch corresponding to the difference equal to or greater than the predetermined value. Secondary test image data generation means for generating secondary test image data for forming a secondary test image used for density correction on a recording medium, in which a second patch group consisting of patches of the above is arranged And an image processing apparatus. In the primary test image, the first patch group includes a plurality of the patches formed with a plurality of different halftone dot densities, and a plurality of the first patch groups having different colors in the main scanning direction are arranged. A plurality of the first patch groups having different colors in the sub-scanning direction are arranged,
In the secondary test image, a plurality of the second patches formed with a higher number of halftone dot densities than the number of halftone dot densities of the plurality of first patches constituting the primary test image are arranged, The image processing apparatus according to claim 1, wherein the second patches having different halftone dot densities are arranged in the main scanning direction, and the second patches having different halftone dot densities are arranged in the sub-scanning direction. The plurality of first patches arranged in the primary test image are each formed with a plurality of halftone dot densities,
The measured density value calculating means calculates a measured density value for each of a plurality of halftone dot densities,
The image processing apparatus according to claim 1, wherein the difference calculating unit calculates a difference between a value related to the calculated measured density value and a target density value corresponding to a halftone dot density of the corresponding first patch. . Based on the measured density value calculated for each of the plurality of halftone dot densities, the measurement density representative value determining means for determining a representative value of the measured density for each of the plurality of halftone dot densities,
The image processing apparatus according to claim 3, wherein the difference calculation unit calculates a difference between the determined measured density representative value and a target density value corresponding to a halftone dot density of the corresponding first patch. It further has an acceptance means for accepting designation of the area from the user,
The measured density representative value determining means determines the measured density of the first patch corresponding to the received area among the measured density values calculated for each of the plurality of halftone densities. The image processing apparatus according to claim 4, wherein the image processing apparatus is determined as a representative value of the measured density corresponding to each. The image processing apparatus according to claim 5, wherein the reception unit receives a designation of a position in the main scanning direction or a designation of a position in the sub scanning direction from a user. The secondary test image data generation means has a halftone dot density at intervals smaller than other halftone dot densities in the vicinity of a halftone dot density where the difference calculated by the difference calculation means is larger than a predetermined value. The image processing apparatus according to claim 3, wherein secondary test image data for forming a secondary test image on a recording medium is generated so that the plurality of formed second patches are arranged. . The accepting means accepts designation of halftone dot density from a user,
In the secondary test image data generation means, a plurality of second patches having halftone dot densities formed at intervals smaller than other halftone dot densities are arranged in the vicinity of the designated halftone dot density. The image processing apparatus according to claim 3, wherein secondary test image data for forming a secondary test image on a recording medium is generated. The image processing apparatus according to claim 1, further comprising an in-plane unevenness correcting unit that corrects in-plane unevenness based on the measured density value calculated by the measured density value calculating unit. Image reading means for reading an image;
Image forming means for forming an image on a recording medium;
A primary test image in which a plurality of first patch groups including one or a plurality of first patches formed in one color are arranged, and a plurality of the first patch groups of a plurality of colors are arranged in the main scanning direction. A primary test image for forming a primary test image on the recording medium by the image forming means, which is arranged so as to exist and arranged so that a plurality of the first patch groups of a plurality of colors exist in the sub-scanning direction. Primary test image data generating means for generating data;
The first test image included in the first patch group output on the recording medium from the reading data of the primary test image obtained by reading the primary test image formed on the recording medium by the image reading unit. A measured density value calculating means for calculating a measured density value corresponding to the patch;
Difference calculating means for calculating a difference between the calculated value relating to the measured density value and a target density value corresponding to the corresponding first patch;
When the calculated difference is equal to or greater than a predetermined value, a plurality of second colors formed with one color for each color of the first patch corresponding to the difference equal to or greater than the predetermined value. A secondary test image data for forming a secondary test image used for density correction on a recording medium by the image forming means, in which a second patch group consisting of patches of the above is arranged. An image forming apparatus comprising: test image data generating means. Image forming means for forming an image on a recording medium;
A primary test image in which a plurality of first patch groups including one or a plurality of first patches formed in one color are arranged, and a plurality of the first patch groups of a plurality of colors are arranged in the main scanning direction. A primary test image for forming a primary test image on the recording medium by the image forming means, which is arranged so as to exist and arranged so that a plurality of the first patch groups of a plurality of colors exist in the sub-scanning direction. Primary test image data generating means for generating data;
Measurement corresponding to the first patch included in the first patch group output on the recording medium from the read data of the primary test image obtained by reading the primary test image formed on the recording medium A measured concentration value calculating means for calculating a concentration value;
Difference calculating means for calculating a difference between the calculated value relating to the measured density value and a target density value corresponding to the corresponding first patch;
When the calculated difference is equal to or greater than a predetermined value, a plurality of second colors formed with one color for each color of the first patch corresponding to the difference equal to or greater than the predetermined value. A secondary test image data for forming a secondary test image used for density correction on a recording medium by the image forming means, in which a second patch group consisting of patches of the above is arranged. An image forming apparatus comprising: test image data generating means. An image reading device for reading an image;
An image forming apparatus for forming an image on a recording medium;
An image processing apparatus,
The image processing apparatus includes:
A primary test image in which a plurality of first patch groups including one or a plurality of first patches formed in one color are arranged, and a plurality of the first patch groups of a plurality of colors are arranged in the main scanning direction. A primary test image for forming a primary test image on a recording medium by the image forming apparatus, the primary test image being arranged to exist and arranged so that a plurality of the first patch groups of a plurality of colors exist in the sub-scanning direction. Primary test image data generating means for generating data;
The first test image included in the first patch group output on the recording medium from the reading data of the primary test image obtained by reading the primary test image formed on the recording medium by the image reading device. A measured density value calculating means for calculating a measured density value corresponding to the patch;
Difference calculating means for calculating a difference between the calculated value relating to the measured density value and a target density value corresponding to the corresponding first patch;
When the calculated difference is equal to or greater than a predetermined value, a plurality of second colors formed with one color for each color of the first patch corresponding to the difference equal to or greater than the predetermined value. A secondary test for generating secondary test image data for forming a secondary test image used for density correction on a recording medium by the image forming apparatus, in which a second patch group consisting of the patches is arranged An image processing system comprising: image data generating means. A primary test image in which a plurality of first patch groups including one or a plurality of first patches formed in one color are arranged, and a plurality of the first patch groups of a plurality of colors are arranged in the main scanning direction. A primary test for generating primary test image data for forming on a recording medium a primary test image arranged to exist and arranged so that a plurality of the first patch groups of a plurality of colors exist in the sub-scanning direction. An image data generation step;
Measurement corresponding to the first patch included in the first patch group output on the recording medium from the read data of the primary test image obtained by reading the primary test image formed on the recording medium A measured concentration value calculating step for calculating a concentration value;
A difference calculating step of calculating a difference between the calculated value relating to the measured density value and a target density value corresponding to the corresponding first patch;
When the calculated difference is equal to or greater than a predetermined value, a plurality of second colors formed with one color for each color of the first patch corresponding to the difference equal to or greater than the predetermined value. A secondary test image data generation step for generating secondary test image data for forming a secondary test image used for density correction on a recording medium, in which a second patch group consisting of the patches is arranged; An image processing program for causing a computer to execute.

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