JP2009010837A - Program of image-forming system and image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image-forming system that uses a white ground region at the periphery of a patch image to create a white reference and obtains density information on the patch image precisely when reading the patch image for adjusting density. <P>SOLUTION: In this manner, an influence distance (d) from an image region affecting the read of a white ground section is calculated, and the density information on the patch image is corrected based on the density information of the white ground section separated as compared with the influence distance (d) at the periphery of the patch image to the density information of the patch image. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming system program for reading a patch image for density adjustment and an image forming system.

  As the density adjustment of the image forming apparatus, there is one that forms a color patch for density adjustment on a sheet, measures the density of the formed color patch, and adjusts the density of the image forming apparatus based on the measurement result.

  In Patent Document 1, as such a density adjustment function, a large number of color patch groups with different writing values are arranged and output on a sheet, and an output image is read by a reading unit, thereby reducing errors due to density unevenness. A color image recording apparatus that performs highly accurate calibration is disclosed.

  However, when a color patch formed on a sheet is read by a reading unit, the read density data of the color patch may be affected by the state of the underlying sheet. For example, there is a case where the paper flickers or rises when reading is performed, or the background color of the paper is not white. In such a case, the density data of the color patch cannot be obtained accurately, and therefore calibration cannot be performed with high accuracy.

With respect to such a problem, in Patent Document 2, white data serving as a white reference is obtained from each paper white area adjacent to the upstream side in the printing direction with respect to the color patches arranged in the horizontal direction on the paper. A printing apparatus that corrects density data read from each color patch is disclosed.
JP-A-8-9178 JP 2002-120357 A (page 11, FIG. 6B)

  However, the printing apparatus disclosed in Patent Document 1 does not take into account the characteristics of the reading unit that is easily affected by adjacent color patches when reading a paper white area. For this reason, when reading in the vicinity of a color patch adjacent to the paper white area, an accurate white reference may not be obtained due to the influence of the color patch.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention is an image that can obtain density information of a patch image with high accuracy by creating a white reference using a white background area around the patch image when reading a patch image for density adjustment. The purpose is to obtain a forming system.

  The above object is achieved by the invention described below.

(1) image forming means for forming a patch image for density adjustment on paper;
A line light source unit that emits irradiation light that spreads in the main scanning direction with respect to the paper, and reading the surface of the paper by detecting light reflected from the line light source unit on the paper for each pixel. A line reading unit in which a plurality of image sensors are arranged one-dimensionally in the main scanning direction, and a reading device that reads image data from a sheet by moving the reading surface in the sub-scanning direction;
An image forming system program comprising:
This affects the reading of the white background portion based on the density information of the white background portions at different distances from the image region in the white background region adjacent to the image region placed on the paper in the sub-scanning direction. An influence range calculating step for calculating an influence distance dy in the sub-scanning direction from the image area;
A reading step for reading the paper on which the patch image for density adjustment is formed;
A patch image density information acquisition step for acquiring density information of a patch image from the image data read in the reading step;
Acquisition of density information of a white background portion away from the patch image by a distance longer than the influence distance dy in the sub-scanning direction calculated in the influence range calculation step in the white background region adjacent to the patch image in the sub-scanning direction from the image data Adjacent white background portion density information acquisition step,
A paper white reference density information acquisition step for acquiring density information in a plurality of white background portions of the paper from the image data;
A correction step for correcting the density information acquired in the patch image density information acquisition step based on the density information acquired in the adjacent white background density information acquisition step and the paper white reference density information acquisition step;
A program for an image forming system to be executed by a computer.

(2) In the influence range calculation step, reading of the white background portion is performed based on density information of a plurality of white background portions in which the distance from the image region is different in the white background region adjacent to the image region in the main scanning direction. Further calculating an influence distance dx in the main scanning direction from the affected image area;
In the adjacent white background portion density information acquisition step, a distance longer than the influence distance dx in the main scanning direction calculated in the influence range calculation step in the white background region adjacent to the patch image in the main scanning direction is separated from the patch image. The program for an image forming system according to (1), wherein density information of a white background portion is acquired.

  (3) The program for an image forming system according to (2), wherein in the adjacent white background portion density information acquisition step, density information of a white background portion of a white background region adjacent to all four sides of the patch image is acquired.

(4) image forming means for forming a patch image for density adjustment on paper;
A line light source unit that emits irradiation light that spreads in the main scanning direction with respect to the paper, and reading the surface of the paper by detecting light reflected from the line light source unit on the paper for each pixel. A line reading unit in which a plurality of image sensors are arranged one-dimensionally in the main scanning direction, and a reading device that reads image data from a sheet by moving the reading surface in the sub-scanning direction;
An image forming system comprising:
This affects the reading of the white background portion based on the density information of the white background portions at different distances from the image region in the white background region adjacent to the image region placed on the paper in the sub-scanning direction. An influence range calculating means for calculating an influence distance dy in the sub-scanning direction from the image area;
Patch image density information acquisition means for acquiring density information of the patch image from the image data of the paper on which the patch image for density adjustment read by the reading device is formed;
Acquisition of density information of a white background portion away from the patch image by a distance longer than the influence distance dy in the sub-scanning direction calculated by the influence range calculation means in a white background region adjacent to the patch image in the sub-scanning direction from the image data Adjacent white background density information acquisition means for performing,
Paper white reference density information acquisition means for acquiring density information in a plurality of white background portions of the paper from the image data;
Correction means for correcting the density information acquired by the patch image density information acquisition means based on the density information acquired by the adjacent white background portion density information acquisition means and the paper white reference density information acquisition means;
An image forming system comprising:

(5) The influence range calculation means reads the white background portion based on the density information of the white background portions at different distances from the image region in the white background region adjacent to the image region in the main scanning direction. Further calculating an influence distance dx in the main scanning direction from the affected image area;
The adjacent white background density information acquisition unit further moves away from the patch image by a distance longer than the influence distance dx in the main scanning direction calculated by the influence range calculation unit in the white background region adjacent to the patch image in the main scanning direction. The image forming system according to (4), wherein the white background portion is read.

  (6) The image forming system according to (5), wherein the adjacent white background portion density information acquisition unit acquires density information of a white background portion of a white background region adjacent to all four sides of the patch image.

  (7) A plurality of the patch images for density adjustment are arranged on a single sheet, and between each patch image, the main scanning direction is more than twice dx and the sub-scanning direction is twice dy. The image forming system according to any one of (4) to (6), wherein the image forming system is arranged at an interval exceeding the interval.

  According to the present invention, when reading a patch image for density adjustment, an image forming system capable of creating a white reference using a white background area around the patch image and obtaining density information of the patch image with high accuracy. Can be obtained.

  Although the present invention will be described based on an embodiment, the present invention is not limited to the embodiment.

  FIG. 1 is a diagram showing a configuration diagram of an image forming system according to an embodiment of the present invention. The image forming system includes a reading device 1 (image reading device), a control terminal 4, and an image forming device 5, which are connected to each other via a communication network N.

When density adjustment (color calibration) is performed in the image forming system, the image forming apparatus 5 forms an image on a sheet based on the image data in which the patch image transmitted from the control terminal 4 is arranged. The control terminal 4 acquires image data by causing the reading device 1 to read the patch image formed on the paper, analyzes the obtained image data, and sets the image forming conditions of the image forming device based on the analysis result. provide feedback.
[Reader]
The reading apparatus will be described with reference to FIGS. FIG. 2A is a cross-sectional view of the reading device 1 according to the embodiment, and FIG. 2B is a perspective view. 2 (a) and 2 (b), the reading apparatus 1 is arranged on an automatic document feeder 10 for automatically conveying a document, and a document conveyed by the automatic document feeder 10 or a glass document table. It comprises a reading means 20 for reading a placed document and an operation display unit 30.

  The automatic document feeder 10 is attached to the reading apparatus main body by a hinge portion 19 and can be opened with respect to the reading apparatus main body as shown in FIG.

  When a single document, for example, a sheet on which a patch image is formed, is placed on the glass platen 22, a linear light source that irradiates the document with irradiation light that spreads in the main scanning direction (x direction). Light irradiation is performed by a line light source 231 (hereinafter simply referred to as a light source 231) of a certain first mirror unit 23. The light reflected from the document is imaged on a line reading unit 26 as an imaging unit by an imaging lens 25 as an imaging unit via the mirrors of the first mirror unit 23 and the second mirror unit 24. The line reading unit 26 is a unit that reads an image of a document, and receives an image sensor (photoelectric conversion device) that receives light reflected from the document and performs photoelectric conversion for each pixel in a one-dimensional manner in the main scanning direction (x direction). It is composed of line sensors (line CCDs) arranged in a line, and reads an image of a document (sheet surface) in units of one line in the main scanning direction.

  The first mirror unit 23 having the light source 231 moves in the sub-scanning direction (y direction) orthogonal to the main scanning direction, and the second mirror unit 24 has a moving speed that is ½ of the moving speed of the first mirror unit. Are configured to move in the same direction. Therefore, the reading surface can be moved in the sub-scanning direction by moving the optical system of the first mirror unit 23 and the second mirror unit 24 in the sub-scanning direction with respect to the document on the document table 22. By sequentially moving the reading surface in the sub-scanning direction, the entire surface of the document can be scanned, and the light reflected from the document can be sequentially read by the line reading unit 26 to read an image of one document. .

  The automatic document feeder 10 feeds a plurality of sheet-like documents D placed on the document table 11, for example, a sheet on which a patch image is formed, one by one to the conveyance path by the separation roller 12, and a plurality of guides. The document is transported by a document transport unit 13 including a member and a plurality of rollers, and is discharged onto a document discharge table 15. The image of the document D being conveyed is read by the reading unit 20 at the document image reading position 21 in the conveyance path. That is, the reading surface can be moved in the sub-scanning direction by moving the document.

  When reading images on both sides of the document, the document reversing unit 16 comprising a pair of rollers and a conveyance path switching guide reverses the document D on which the image on the front surface (first surface) has been read, and again conveys the document. Sent to the unit 13. The document from which the image on the back surface (second surface) is read is discharged onto the document discharge table 15.

  As described above, the reading device 1 can read not only the document placed directly on the glass document table 22 but also the document conveyed by the automatic document feeder 10. In other words, by moving the optical system of the reading unit or the document in the sub-scanning direction, the reading surface of the reading unit and the surface to be read (read surface) of the document are relatively moved in the sub-scanning direction to move from the entire surface of the document. Read image data.

  FIG. 3 is a block diagram of a control system in the reading apparatus 1. In the figure, the periphery of the part necessary for the explanation of the operation of the present embodiment is mainly described, and other parts known as the reading device 1 are omitted.

  The reading apparatus 1 includes a CPU 101 functioning as a control unit (control unit), a ROM 102, a RAM 103, an HDD 104, a communication I / F 105, a system bus 106, an automatic document feeding unit 10, a reading unit 20, an operation unit 30, and an image processing unit 110. Have.

  A CPU (Central Processing Unit) 101 that functions as a control unit (control means) controls the overall operation of the reading apparatus 1, and via a system bus 106, a ROM (Read Only Memory) 102 and a RAM (Random Access Memory). ) 103 or the like. The CPU 101 reads out various control programs stored in the ROM 102, develops them in the RAM 103, and controls the operation of each unit. In addition, the CPU 101 executes various processes according to the program expanded in the RAM 103, stores the processing results in the RAM 103, and displays them on the operation display unit 30. Then, the processing result stored in the RAM 103 is stored in a predetermined storage destination.

  The ROM 102 stores programs, data, and the like in advance, and this recording medium is composed of a magnetic or optical recording medium or a semiconductor memory. The RAM 103 forms a work area that temporarily stores data processed by various control programs executed by the CPU 101.

  A signal output from the image sensor of the line reading unit 26 is A / D converted by an IC arranged in the vicinity of the image sensor and sent to the control unit. The sent signal is subjected to processing such as shading correction and compression in the image processing unit 110, and is stored as image data in an HDD (hard disk drive) 104.

  The communication I / F 105 communicates print data including image data, programs, various data, and the like with the image forming apparatus 5 and the like via the network N.

  The operation display unit 30 includes a liquid crystal display unit and a touch panel operation unit arranged on the liquid crystal display unit, and displays and sets various information.

[Control terminal]
FIG. 4 is a block diagram of a control system in the control terminal 4. In the figure, the periphery of the part necessary for the explanation of the operation of the present embodiment is mainly described, and other parts known as control terminals are omitted.

  The control terminal 4 is a so-called personal computer. In the control terminal 4, the display unit 431 has a liquid crystal display unit, and displays various types of information. The operation unit 432 includes a keyboard and a mouse and performs various inputs. The other CPU 401, ROM 402, RAM 403, HDD 404, communication I / F 405, and system bus 406 have the same functions as those having the same names in FIG.

  The CPU 401 reads out various control programs stored in the ROM 402, develops them in the RAM 403, and controls the operation of each unit. The CPU 401 functions as “influence range calculation means”, “patch image density information acquisition means”, “adjacent white background density information acquisition means”, “paper white reference density information acquisition means”, and “correction means”.

[Image forming apparatus]
FIG. 5 is a block diagram of a control system in the image forming apparatus 5. In the figure, the periphery of the part necessary for the explanation of the operation of the present embodiment is mainly described, and other parts known as the image forming apparatus are omitted.

  The print controller unit 507 includes a CPU (not shown), a memory, an image processing unit, and the like, and can control image data received from the control terminal 4 via the communication I / F 505 in the image forming apparatus. This is converted to image data.

  The image forming unit 50 forms an image on a sheet based on the image data. As the image forming apparatus, for example, an electrophotographic full-color image forming apparatus using four color toners of Y (yellow), M (magenta), C (cyan), and Bk (black), or an ink-jet full-color image forming apparatus. Is used. When density adjustment is performed, a patch image for density adjustment is formed on a sheet in accordance with an instruction from the control terminal 4, the patch image formed on the sheet is read by the reading device 1, and the read image data is read from the control terminal. Process and judge at 4. Based on the result, the control terminal 4 instructs the density control unit 60, and the density control unit 60 changes the image forming conditions of the image forming unit 50 based on the instruction. By these density adjustments, the γ curve of the image output from the image forming apparatus 5 is adjusted to a predetermined target value.

  Note that in this article, image data is a set of pixels having density information (also referred to as pixel values) and position information. The density information includes color information and luminance information. The color information is information indicating the type of color such as C, M, Y, Bk or R, G, B, and the luminance information is the gradation of each color (for example, 8-bit 256 gradation number). Information indicating whether to output in 200 gradations. As an example of density information, in the expression method of 256 gradations for each RGB color, if Y color, it is expressed as R (255) G (255) B (0).

[Control flow]
FIG. 6 is a flowchart illustrating a control flow of the image forming system. The flowchart is a process executed by software processing by the cooperation of programs stored in the CPU 401 and the ROM 402 of the control terminal 4.

[Control flow (1) Reading device performance]
First, in steps S11 and S12, the influence range of the reading device is investigated. In consideration of the characteristic of the reading apparatus that is easily affected by the adjacent patch image when reading the white background portion, the influence range is examined in advance. In other words, it grasps the performance of the reading device. In principle, if the reading device and the paper type to be used are the same, the flow of steps S11 and S12 need only be executed once, and the previous result is used thereafter. Thus, this flow can be omitted.

  The influence range investigation method will be described with reference to FIGS. FIG. 7 is a schematic diagram for explaining the positional relationship between the image area Ga and one white background portion s. FIG. 8 is an example of a measurement pattern in which a plurality of white background portions s and image areas Ga shown in FIG. 7 are arranged on one sheet of paper k.

  In FIG. 7, a white background area Wa is a non-image forming area, and image areas Ga are arranged on both sides of the white background area Wa. The image area Ga is an area where an image is formed. For example, in the case of an electrophotographic image forming apparatus, an area where a 100% output density (maximum density) image of Bk toner (hereinafter referred to as Bk solid) is formed. That is. Bk toner is used because it has the largest color difference from the white background. The white background portion s is a portion (measurement location) where density information is acquired, and is located at the center of the white background region Wa. That is, the white background portion s has the same distance d from the image regions Ga on both sides. In the figure, for the sake of explanation, a broken-line square frame is shown, but no image is actually formed.

  FIG. 8A is an example of a measurement pattern in which the white background portion s and the image region Ga as shown in FIG. 7 are arranged on one sheet of paper k. As shown in the figure, the white background portions s1 to s5 in the white background area Wa adjacent to the image area Ga have different distances from the image area Ga from d1 to d5, respectively, and d1 has the shortest distance. , D5 has the longest distance.

  In the example shown in the figure, the embodiment using the five-level distance d has been described. However, the present invention is not limited to this, and the image area Ga may be arranged to have more levels. The example shown in the figure is an example in which the center of the paper is a white background portion s and two image areas Ga are arranged on both sides thereof. However, a single rectangular image area Ga is provided to remove the image area from the image area Ga. The influence distance d may be calculated by acquiring the density information of the white background portion with different distances.

  FIG. 9 is a diagram illustrating an example of a result obtained by measuring the white background portions s1 to s5 of FIG. The horizontal axis is the distance d from the image area in the white background. The vertical axis plots the luminance information of Red, Green, and Blue as the density information of the white background portion as a ratio with respect to the maximum luminance of 100%.

  As shown in the figure, the luminance information of the density information at the distance d1 (the white background portion s1 having the shortest distance from the image region) is the smallest, and the luminance information increases as the distances d2 and d3 become longer. ing. This is because when the reading device 1 performs reading, not only the reflected light of the reading target portion but also the reflected light of the peripheral area is received by the image sensor. When there is Bk solid in the peripheral area, there is almost no reflected light from the Bk solid, so the amount of light received by the image sensor decreases. In particular, when the distance between the white background portion s to be measured and the Bk solid is close, the influence becomes significant.

  Further, in the present embodiment, the line light source unit 231 of the reading apparatus 1 irradiates the sheet with irradiation light having a spread in the main scanning direction x, so that it is adjacent to the white background s in the main scanning direction x. The influence of the image area Ga to be applied tends to be larger than the influence of the image area Ga adjacent in the sub-scanning direction y.

  The above is step S11. In the next step S12 (: influence range calculation step), the influence distance d from the image area that affects the white background reading is calculated based on the distance from the image area of the white background and the density information of the white background. In the example shown in FIG. 9, the density information obtained by measuring the white background portions s1, s2, and s3 corresponding to the distances d1, d2, and d3 is affected by the image area Ga, and the white background portion having the distance d4 or more. In s4 and s5, it can be determined that the luminance information is saturated and is not affected by the image area Ga. In such a case, the maximum value of the influence distance is d3.

  The measurement pattern in the sub-scanning direction y shown in FIG. 8A is read by the reading device 1 to obtain image data, and the influence distance dy in the sub-scanning direction is calculated for the obtained image data by the procedure described above. Do. FIG. 8B shows a measurement pattern obtained by rotating FIG. 8A by 90 degrees. By reading the paper on which the measurement pattern is formed with the reading device 1, the influence distance dx in the main scanning direction x is further performed in the same procedure. May be calculated.

[Control flow (2) Patch image density measurement]
In step S13, patch image forming conditions are input. The patch image forming conditions are color information for performing image adjustment, density information for each color, the number of stages, and the number of repetitions. By inputting these from the operation unit 432, the number of patch images to be arranged on one sheet can be determined. For example, FIG. 10A shows an example in which patch images are arranged with color information Bk, density information (100%, 75%, 50%, 25%), number of stages 4, and number of repetitions 1.

  In step S14, the number of patch images determined in step S13 are separated from each other with an interval exceeding twice the influence distance dx in the main scanning direction and twice the influence distance dy in the sub-scanning direction calculated in step S12. The arrangement pattern is determined so as to be arranged on the paper. This is to ensure a white background portion (used in step S162 described later) that is separated from each patch image by a distance exceeding dx and dy.

  The determined arrangement pattern is stored in the HDD 404 of the control terminal 4 and transmitted to the image forming apparatus 5 via the network N. In the image forming apparatus 5, a patch image is formed on a sheet by the image forming unit 50 based on the received arrangement pattern.

  In step S15 (: reading step), image data is acquired by reading the patch image formed on the paper with the reading device 1. The read image data is stored in the HDD 404 of the control terminal 4 via the network N. In the subsequent subroutine of step S16, the density information of the pixels of the patch image and the surrounding white background area is acquired based on the image data obtained in step S15.

[S16 subroutine for obtaining density information]
The subroutine of step S16 will be described based on FIG. In step S161 (: patch image density information acquisition step), the arrangement pattern (acquired in S14) stored in the HDD 404 of the control terminal 4 and the image data (acquired in S15) are associated with each other to obtain one patch image. The density information corresponding to the position of is acquired.

  Subsequently, in step S162 (: adjacent white background density information acquisition step), the density information of the white background of the white background area adjacent to the patch image whose density information has been acquired in step S161 is acquired. The positional relationship between the white background portion and the patch image will be described with reference to FIG.

  FIG. 10A shows the arrangement of four patch images pa1 to pa4 on the sheet k, and FIG. 10B shows an enlargement of the periphery of one of the patch images pa2. When acquiring density information of the white background portion of the white background area adjacent to the patch image pa2, a white background separated from the patch image pa2 by a distance longer than the influence distance dx in the main scanning direction calculated in step S12 from the patch image pa2. The density information of the part sx is acquired. Similarly, in the sub-scanning direction, the density information of the white background portion sy that is separated from the patch image pa2 by a distance longer than the influence distance dy in the sub-scanning direction is acquired. In the figure, the adjacent patch images in step S14 described above are arranged so as to be separated from each other by a distance longer than twice dx and dy, so that the white background portions sx and sy can be secured.

  In the present embodiment, the example in which the density information of the white background portion is acquired from the white background portion sx adjacent in the main scanning direction together with the white background portion sy adjacent in the sub-scanning direction to the patch image to be measured. You may make it acquire the density information of the white background part only in a subscanning direction. In general, in a reading apparatus having a line light source having a spread of irradiation light in the main scanning direction x with respect to the paper, the influence of the reflected light in the peripheral area is large in the main scanning direction, so the white background area This is because it is difficult to secure.

  Further, when the influence distance dx is longer than a predetermined value, for example, when it exceeds 30 mm, the density information of the white background portion sy in the sub-scanning direction is not acquired without acquiring the density information in the white background portion sx in the main scanning direction. You may make it acquire only. The purpose of acquiring the density information of the white background around the patch image is to correct the influence on the density information due to the paper state at the center patch image position, for example, fluttering or floating, but the influence distance dx is This is because the purpose cannot be secured in the case of a long time.

  In step S163, it is determined whether or not the acquisition of the density information of the patch image itself and the surrounding white background has been completed for all the patch images included in the image data obtained in step S15. If there is not (step S163: No), the processes of steps S161 and S162 are repeated. On the other hand, when the processing is completed (step S163: Yes), the processing of the next step is performed.

  In step S164 (: paper white reference density information acquisition step), density information of white background portions sp of a plurality of white background areas is acquired over a wide area of the paper, and the average value of the obtained density information of the plurality of places or The median value is used as the paper white reference density information. This is because the density information of the sheet itself is acquired by acquiring the density information of the non-image portion of the sheet. For example, in the example shown in FIG. 10, the density information is acquired from the white background portion sp that is farther than the influence distances dx and dy from the image area (patch image). When this step ends, the subroutine ends (returns).

[S17 subroutine for density information correction]
Returning to the flow of FIG. In the next step S17 (: correction step), the density information is corrected. The subroutine of step S17 will be described with reference to FIG.

  In step S171, the paper white reference density information Dsp obtained in step S164 is acquired.

  In step S172, the density information Dpn of one (nth) patch image obtained in steps S161 and S162 and the peripheral white background density information Dwn of the patch image are acquired.

In step S173, patch density correction is executed. The patch density correction is performed by the following formula based on the information acquired in S171 and S172.
Patch density information after correction Dpn2 = Dpn × Dsp / Dwn
For example, if the image data has luminance information of 256 tones (8 bits) of RGB for each pixel and the R information is Dpn, Dsp, and Dwn of 127, 225, and 235, respectively, the corrected patch density information Dpn2 = 127 × 225/235 = 122.

  The flow after step S172 is repeated until the process is completed for all patch images (step S174: No). When the process is completed for all patch images (step S174: Yes), the subroutine ends (returns). ) And the control flow of FIG. 6 ends.

  In this manner, the influence distance d from the image area that affects the reading of the white background portion is calculated, and the density information of the white background portion that is farther than the influence distance d in the peripheral portion of the patch image is calculated with respect to the density information of the patch image. By correcting the density information of the patch image based on this, it is possible to provide an image forming system that reads the patch image with high accuracy.

1 is a configuration diagram of an image forming system in an embodiment of the present invention. (A) Sectional drawing of the reader 1 which concerns on embodiment. (B) It is the perspective view. 3 is a block diagram of a control system in the reading apparatus 1. FIG. 3 is a block diagram of a control system in a control terminal 4. FIG. 3 is a block diagram of a control system in the image forming apparatus 5. FIG. 3 is a flowchart illustrating a control flow of the image forming system. It is a schematic diagram explaining the positional relationship of the image area | region Ga and the one white background part s. 8 is an example of a measurement pattern in which a plurality of white background portions s and image areas Ga as shown in FIG. 7 are arranged on one sheet of paper k. It is a figure which shows the example of the result of having performed the measurement of the white background part s1 to s5 of Fig.8 (a) with the reader 1. FIG. (A) is one in which four patch images pa1 to pa4 are arranged on a sheet k, and (b) is an enlarged view of the periphery of one patch image pa2. This is a subroutine of step S16 in FIG. This is a subroutine of step S17 in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reading apparatus 10 Automatic document feeding means 20 Reading means 23 1st mirror unit 24 2nd mirror unit 26 Line reading part 231 Line light source 4 Control terminal 5 Image forming apparatus

Claims (7)

Image forming means for forming a patch image for density adjustment on paper;
A line light source unit that emits irradiation light that spreads in the main scanning direction with respect to the paper, and reading the surface of the paper by detecting light reflected from the line light source unit on the paper for each pixel. A line reading unit in which a plurality of image sensors are arranged one-dimensionally in the main scanning direction, and a reading device that reads image data from a sheet by moving the reading surface in the sub-scanning direction;
An image forming system program comprising:
This affects the reading of the white background portion based on the density information of the white background portions at different distances from the image region in the white background region adjacent to the image region placed on the paper in the sub-scanning direction. An influence range calculating step for calculating an influence distance dy in the sub-scanning direction from the image area;
A reading step for reading the paper on which the patch image for density adjustment is formed;
A patch image density information acquisition step for acquiring density information of a patch image from the image data read in the reading step;
Acquisition of density information of a white background portion away from the patch image by a distance longer than the influence distance dy in the sub-scanning direction calculated in the influence range calculation step in the white background region adjacent to the patch image in the sub-scanning direction from the image data Adjacent white background portion density information acquisition step,
A paper white reference density information acquisition step for acquiring density information in a plurality of white background portions of the paper from the image data;
A correction step for correcting the density information acquired in the patch image density information acquisition step based on the density information acquired in the adjacent white background density information acquisition step and the paper white reference density information acquisition step;
A program for an image forming system to be executed by a computer. In the influence range calculating step, the reading of the white background portion is affected based on the density information of the white background portions at different distances from the image region in the white background region adjacent to the image region in the main scanning direction. Further calculating the influence distance dx in the main scanning direction from the image area;
In the adjacent white background portion density information acquisition step, a distance longer than the influence distance dx in the main scanning direction calculated in the influence range calculation step in the white background region adjacent to the patch image in the main scanning direction is separated from the patch image. The image forming system program according to claim 1, wherein density information of a white background portion is acquired. 3. The image forming system program according to claim 2, wherein in the adjacent white background portion density information acquisition step, density information of a white background portion of a white background region adjacent to all four sides of the patch image is acquired. Image forming means for forming a patch image for density adjustment on paper;
A line light source unit that emits irradiation light that spreads in the main scanning direction with respect to the paper, and reading the surface of the paper by detecting light reflected from the line light source unit on the paper for each pixel. A line reading unit in which a plurality of image sensors are arranged one-dimensionally in the main scanning direction, and a reading device that reads image data from a sheet by moving the reading surface in the sub-scanning direction;
An image forming system comprising:
This affects the reading of the white background portion based on the density information of the white background portions at different distances from the image region in the white background region adjacent to the image region placed on the paper in the sub-scanning direction. An influence range calculating means for calculating an influence distance dy in the sub-scanning direction from the image area;
Patch image density information acquisition means for acquiring density information of the patch image from the image data of the paper on which the patch image for density adjustment read by the reading device is formed;
Acquisition of density information of a white background portion away from the patch image by a distance longer than the influence distance dy in the sub-scanning direction calculated by the influence range calculation means in the white background region adjacent to the patch image in the sub-scanning direction from the image data Adjacent white background density information acquisition means for performing,
Paper white reference density information acquisition means for acquiring density information from a plurality of white areas of the paper from the image data;
Correction means for correcting the density information acquired by the patch image density information acquisition means based on the density information acquired by the adjacent white background portion density information acquisition means and the paper white reference density information acquisition means;
An image forming system comprising: The influence range calculating means affects the reading of the white background portion based on density information of a plurality of white background portions that are different in distance from the image region in the white background region adjacent to the image region in the main scanning direction. Further calculating the influence distance dx in the main scanning direction from the image area;
The adjacent white background density information acquisition unit further moves away from the patch image by a distance longer than the influence distance dx in the main scanning direction calculated by the influence range calculation unit in the white background region adjacent to the patch image in the main scanning direction. The image forming system according to claim 4, wherein a white background portion is read. 6. The image forming system according to claim 5, wherein the adjacent white background portion density information acquiring unit acquires density information of a white background portion of a white background region adjacent to all four sides of the patch image. A plurality of patch images for density adjustment are arranged on one sheet, and between each patch image, an interval in which the main scanning direction exceeds twice dx and a sub-scanning direction exceeds twice dy, The image forming system according to claim 4, wherein the image forming system is arranged as follows.

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