Image processing device, image forming system, image processing method and program

Abstract

Provided are an image processing device, an image forming system, an image processing method, and a program that can realize appropriate control of image forming operations by correcting for reading fluctuations using a printed image without using a dedicated chart. [Solution] The system includes an area determination unit that determines multiple target areas to be used for correcting reading variations in document image data of a printed document image-formed by an image forming device, a calculation unit that calculates correction parameters for correcting the reading variations for the read image data based on read values ​​of areas corresponding to each of the target areas determined by the area determination unit in the read image data read by an image reading device for the printed document, and a first correction unit that corrects the read image data using the correction parameters calculated by the calculation unit.

Description

[Technical Field]

[0001] The present invention relates to an image processing apparatus, an image forming system, an image processing method, and a program. [Background technology]

[0002] Color stabilization mechanisms that correct color variations during continuous printing and contribute to the stability of color in output images are known (see, for example, Patent Document 1). Such color stabilization mechanisms employ a mechanism for capturing color variations from a read image of a printed output image read by an image reading device. In this case, the read image contains color variations caused by the image forming device and color variations caused by the image reading device. One example of color variations (read variations) caused by the image reading device is a noise phenomenon called flare. This is a phenomenon in which the read values ​​of pixels in a target area change due to the influence of diffuse reflection from surrounding areas when reading a read image.

[0003] Also, a mechanism is known in which flare characteristics are acquired from a scanned image of a pre-printed reference chart and flare is removed from the scanned image in the actual printing (see, for example, Patent Document 2). An example of a pre-printed reference chart is a dedicated chart DC, as shown in FIG. 12, on which a plurality of black and white patches are arranged. The dedicated chart DC is then read by a reading device to obtain a scanned image. In the scanned image, a region AR11, which is made up of a target region AA11 from the black patches and a peripheral region SA11 surrounding the target region AA11, and a region AR12, which is made up of a target region AA12 from the white patches and a peripheral region SA12 surrounding the target region AA12, are determined as regions to be used for flare correction. Then, from the scanned image, a read value of a white area of ​​interest AA11 and a read value of an equally white area of ​​interest AA12 are extracted, but due to the influence of diffused reflection caused by flare from the black surrounding area SA11 and the white surrounding area SA12, respectively, a difference occurs between these read values ​​as points P11 and P12, as shown in Fig. 13. Here, the influence of flare from the surrounding areas becomes greater as the read value of the surrounding areas becomes brighter. The difference between the read values ​​of the areas of interest at points P11 and P12 is used to calculate a correction parameter for performing flare correction on the read values ​​of the scanned image. Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technology described in Patent Document 1, it is not possible to accurately observe color variations caused by the image forming device from a scanned image that includes color variations caused by the image reading device, which may lead to erroneous control of the image forming device. Also, with the technology described in Patent Document 2, it is necessary to print a dedicated reference chart for each printing paper before executing processing by the color stabilization mechanism, which causes a problem of incurring trouble for the user.

[0005] The present invention has been made in consideration of the above, and aims to provide an image processing device, an image forming system, an image processing method, and a program that can achieve appropriate control of image forming operations by correcting for reading fluctuations using a printed image without using a dedicated chart. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention is characterized by comprising an area determination unit that determines multiple target areas to be used for correcting reading variations in document image data of a printed document image-formed by an image forming device, a calculation unit that calculates correction parameters for correcting the reading variations in the read image data based on read values ​​of areas corresponding to each of the target areas determined by the area determination unit in the read image data read by an image reading device for the printed document, and a first correction unit that corrects the read image data using the correction parameters calculated by the calculation unit. [Effects of the Invention]

[0007] According to the present invention, it is possible to realize appropriate control of the image forming operation by correcting for reading fluctuations using a printed image, without using a dedicated chart. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the overall configuration of an image forming system according to an embodiment. [Figure 2] FIG. 2 is a diagram for explaining flare. [Figure 3] FIG. 3 is a diagram illustrating an example of a hardware configuration of the image processing apparatus according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of the functional block configuration of the image processing apparatus according to the embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of a functional block configuration of a reading variation correction unit according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of a functional block configuration of a correction parameter generating unit according to the embodiment. [Figure 7] FIG. 7 is a diagram illustrating the operation of determining the area used for flare correction in the image processing device according to the embodiment. [Figure 8] FIG. 8 is a diagram illustrating the flare correction operation of the image processing device according to the embodiment. [Figure 9] FIG. 9 is a diagram showing an example of an update selection screen used in the image processing apparatus according to the embodiment. [Figure 10] FIG. 10 is a diagram showing an example of a correction parameter editing screen used in the image processing apparatus according to the embodiment. [Figure 11] FIG. 11 is a flowchart showing an example of the flow of the correction parameter update process of the image processing device according to the embodiment. [Figure 12] FIG. 12 is a diagram showing an example of a conventional reference chart. [Figure 13] FIG. 13 is a diagram illustrating conventional flare correction. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, with reference to the drawings, embodiments of an image processing device, an image forming system, an image processing method, and a program according to the present invention will be described in detail. Furthermore, the present invention is not limited to the following embodiments, and the components in the following embodiments include those that would be easily conceived by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is called equivalents. Furthermore, various omissions, substitutions, modifications, and combinations of the components can be made without departing from the spirit of the following embodiments.

[0010] (Overall configuration of image forming system) Fig. 1 is a diagram showing an example of the overall configuration of an image forming system according to an embodiment. Fig. 2 is a diagram for explaining flare. The overall configuration of the image forming system 1 according to this embodiment will be described with reference to Figs. 1 and 2.

[0011] 1 is a system for forming an image on a printing sheet from document image data received from a user PC (Personal Computer) 2 via a print server 3. As shown in FIG. 1, the image forming system 1 has an image processing device 10, a paper feed tray 11, a conveyor belt 12, an image forming device 13, an image reading device 14, a paper output tray 15, and a touch panel 16.

[0012] The image processing device 10 is a device that receives original image data that has been image processed (for example, RIP (Raster Image Processor) processing) by the print server 3, and controls the image forming device 13 to form an image on a printing paper P from the RIP image data. The image processing device 10 also controls the image reading device 14 to read the printing paper P on which the image has been formed by the image forming device 13.

[0013] The paper feed tray 11 is a tray for storing print sheets P. The print sheets P stored in the paper feed tray 11 are fed to the conveyor belt 12 one sheet at a time.

[0014] The conveyor belt 12 is a belt for conveying the printing paper P fed from the paper feed tray 11 to the image forming device 13, the image reading device 14, and the paper discharge tray 15 in this order.

[0015] The image forming device 13 is a device that forms an image on the printing paper P conveyed from the conveyor belt 12 based on RIP image data under the control of the image processing device 10.

[0016] The image reading device 14 is a device that performs a reading operation on the printing paper P on which an image has been formed by the image forming device 13, in accordance with the control of the image processing device 10. In other words, the image reading device 14 is disposed after the image forming device 13 on the transport path along which the printing paper P on which the image has been formed is transported. As a result, the image reading device 14 generates a read image of the printing paper P on which the image has been formed, and transmits the read image to the image processing device 10.

[0017] The paper discharge tray 15 is a tray for discharging the print paper P that has been read by the image reading device 14.

[0018] The touch panel 16 is a touch panel that allows a user to input operations and displays various screens and the like.

[0019] The user PC 2 is an information processing device that generates and edits print image data for image formation in the image forming system 1.

[0020] The print server 3 is a server that receives print image data from the user PC 2 and converts the print image data into a data format that enables image formation by the image forming system 1 through RIP processing. The print server 3 transmits the RIP image data converted from the print image data through the RIP processing to the image processing device 10.

[0021] In the image forming system 1 configured as described above, the image processing device 10 performs a process to correct flare contained in the read image using the read image of the printing paper P read by the image reading device 14 and the RIP image data corresponding to the read image received from the print server 3. Here, flare will be described with reference to FIG. 2. As shown in FIG. 2(a), if the amount indicating the degree of flare of pixels in a peripheral region around a target region in a read image where the read value is (R, G, B) = (255, 255, 255) (hereinafter, sometimes simply referred to as a read value of 255) is assumed to be 1, the amount of flare of a pixel in a peripheral region where the read value is n, as shown in FIG. 2(b), is expressed as n / 255. In other words, the read value of the peripheral region and the flare amount can be considered to have a linear relationship. The effect of a specific amount of flare on the target region is reflected in the magnitude of the read value of the target region. 12, it is possible to calculate the amount of flare from the surrounding areas having a read value between 0 and 255 by obtaining the read value of the area of ​​interest surrounded by a black (read value = 0) surrounding area SA11 in area AR11 and the read value of the area of ​​interest surrounded by a white (read value = 255) surrounding area SA12 in area AR12. The amount of correction to the read value that cancels out the influence of flare due to the amount of flare is referred to as a correction parameter.

[0022] To obtain such correction parameters, ideal areas AR11 and AR12 for calculating the amount of flare can be obtained by printing a dedicated chart DC as shown in FIG. 12 in advance as a reference chart. However, such ideal areas cannot be obtained from a scanned image of printed paper formed from document image data. Therefore, in this embodiment, an operation for estimating the amount of flare from a specific area using a scanned image of printed paper formed from print image data will be described.

[0023] (Hardware configuration of image processing device) 3 is a diagram showing an example of the hardware configuration of an image processing device according to an embodiment, and the hardware configuration of the image processing device 10 according to this embodiment will be described with reference to FIG.

[0024] As shown in FIG. 3, the image processing device 10 includes a CPU (Central Processing Unit) 501, a ROM (Read Only Memory) 502, a RAM (Random Access Memory) 503, an auxiliary storage device 505, a network I / F 506, and a touch panel 507.

[0025] The CPU 501 is a computing device that controls the overall operation of the image processing device 10. The ROM 502 is a non-volatile storage device that stores programs such as an IPL (Initial Program Loader) that is initially executed by the CPU 501. The RAM 503 is a volatile storage device that is used as a work area for the CPU 501.

[0026] The auxiliary storage device 505 is a non-volatile storage device that stores various data such as various setting information and programs, etc. The auxiliary storage device 505 is, for example, a hard disk drive (HDD) or a solid state drive (SSD).

[0027] The network I / F 506 is an interface for data communication using a network. The network I / F 506 is, for example, a network interface card (NIC) that enables communication using a transmission control protocol (TCP) / internet protocol (IP). The network I / F 506 may also be a communication interface having a wireless communication function based on a standard such as Wi-Fi (registered trademark).

[0028] The network I / F 506 performs data communication with, for example, the image forming device 13 and the image reading device 14. Note that the image processing device 10 may be provided with, for example, a USB (Universal Serial Bus) I / F or the like, and may perform data communication with the image forming device 13 and the image reading device 14 via the USB I / F.

[0029] The touch panel 507 is a touch panel that allows a user to input operations and display various screens, etc. The touch panel 507 may be a touch panel included in the image processing device 10, or may correspond to the touch panel 16 shown in FIG.

[0030] The above-mentioned CPU 501, ROM 502, RAM 503, auxiliary storage device 505, network I / F 506, and touch panel 507 are connected to each other so as to be able to communicate with each other via a bus line 510 such as an address bus and a data bus.

[0031] The hardware configuration of the image processing device 10 shown in FIG. 3 is an example, and it is not necessary to include all of the components, and other components may also be included.

[0032] (Configuration and operation of functional blocks of image processing device) FIG. 4 is a diagram showing an example of the configuration of functional blocks of an image processing apparatus according to an embodiment. FIG. 5 is a diagram showing an example of the configuration of functional blocks of a reading variation correction unit according to an embodiment. FIG. 6 is a diagram showing an example of the configuration of functional blocks of a correction parameter generation unit according to an embodiment. FIG. 7 is a diagram explaining the operation of determining an area to be used for flare correction in the image processing apparatus according to an embodiment. FIG. 8 is a diagram explaining the flare correction operation in the image processing apparatus according to an embodiment. FIG. 9 is a diagram showing an example of an update selection screen used in the image processing apparatus according to an embodiment. FIG. 10 is a diagram showing an example of a correction parameter editing screen used in the image processing apparatus according to an embodiment. The configuration and operation of the functional blocks of the image processing apparatus 10 according to this embodiment will be described with reference to FIGS. 4 to 10.

[0033] As shown in FIG. 4, the image processing device 10 includes an image processing unit 101, a color variation correction unit 102 (second correction unit), and a reading variation correction unit 103.

[0034] The image processing unit 101 is a functional unit that receives RIP image data converted from document image data by the print server 3 via the network I / F 506 and converts it into reference image data in a data format suitable for correction processing in the color variation correction unit 102. The image processing unit 101 outputs the generated reference image data to the color variation correction unit 102.

[0035] Note that the RIP image data is in a data format compatible with image formation by the image forming device 13, and the reference image data is in a data format suitable for correction processing by the color variation correction unit 102, but these image data are simply in different data formats and are essentially data containing the same content as the original document image data.

[0036] The color variation correction unit 102 is a functional unit that calculates a correction value (hereinafter, sometimes referred to as a color variation correction value) for correcting color variations that occur during image formation by the image forming device 13 by comparing the reference image data generated by the image processing unit 101 with the read image data corrected by the read variation correction unit 103 (hereinafter, sometimes referred to as corrected read image data). The read image data read by the image reading device 14 includes color variations that occur during image formation by the image forming device 13 (hereinafter, sometimes referred to as color variations caused by the image forming device 13) and color variations that occur during the reading operation of the image reading device 14 (hereinafter, sometimes referred to as color variations caused by the image reading device 14). Here, color variations (read variations) caused by the image reading device 14 include read variations due to flare, for example. The details of the correction process of the read image data by the read variation correction unit 103 will be described later, but this correction process corrects color variations caused by the image reading device 14 for the read image data, and color variations caused by the image forming device 13 remain in the corrected read image data. The color variation correction unit 102 calculates a color variation correction value for correcting color variations caused by the image forming device 13 that exist in the corrected read image data by comparing the corrected read image data with the reference image data. The image forming device 13 performs image formation operations using the color variation correction value calculated by the color variation correction unit 102, thereby achieving color stability control.

[0037] The read variation correction unit 103 is a functional unit that uses the RIP image data generated by the print server 3 and the read image data obtained by the image reading device 14 reading operation on the printed paper PS, to perform correction for color variations caused by the image reading device 14 and included in the read image data. The read variation correction unit 103 outputs the corrected read image data generated by the correction to the color variation correction unit 102. As shown in FIG. 5, the read variation correction unit 103 has a correction parameter generation unit 201, a correction parameter update unit 202 (update unit), and a read image correction processing unit 203 (first correction unit).

[0038] The correction parameter generation unit 201 is a functional unit that calculates and generates correction parameters for correcting color variations caused by the image reading device 14 and included in the read image data, using the RIP image data generated by the print server 3 and the read image data obtained by the image reading device 14 reading operation on the printed paper PS. The correction parameter generation unit 201 outputs the generated correction parameters to the correction parameter update unit 202. As shown in FIG. 6, the correction parameter generation unit 201 has an extraction area determination unit 301 (area determination unit), a read value extraction unit 302, and a parameter calculation unit 303 (calculation unit).

[0039] The extraction area determination unit 301 is a functional unit that searches for and determines an area (target area) in the RIP image data (RIP image data corresponding to the printed paper PS) generated by the print server 3 for deriving the characteristics of flare that causes reading variations. For example, as shown in FIG. 7, the area for deriving the flare characteristics is assumed to be a region of interest of a predetermined size composed of multiple pixels and a peripheral region of multiple pixels that surrounds the region of interest and is assumed to have a flare effect on the pixel of interest. The extraction area determination unit 301 determines multiple areas (target areas) in the RIP image data generated by the print server 3 for deriving the flare characteristics, each of which has a corresponding region of interest. In the example shown in FIG. 7, the extraction area determination unit 301 performs, for example, a raster scan on the RIP image data, and determines that a region of interest AA1 in region AR1 and a region of interest AA2 in region AR2 are coincident, and determines the regions AR1 and AR2 as the areas for deriving the flare characteristics. Region AR1 is a region composed of region of interest AA1 and a peripheral region SA1 surrounding region AA1. Region AR2 is a region composed of region of interest AA2 and a peripheral region SA2 surrounding region AA2. Here, regions of interest match when, for example, the positions and pixel values ​​of the pixels constituting the region of interest match, when the pixel values ​​of the pixels constituting the region of interest match regardless of their positions, or when the average pixel values ​​of the pixels constituting the region of interest match. Furthermore, when determining whether pixel values ​​match as described above, regions of interest match does not necessarily mean that they match completely; for example, they may be considered to match if the difference between the pixel values ​​is within a predetermined threshold range.

[0040] The coincidence determination of the regions of interest is not limited to the above, and any publicly known or well-known technique generally used for coincidence determination between regions of image data can be applied. In the example shown in Fig. 7, the extraction region determination unit 301 determines two regions AR1 and AR2, which are regions in which the regions of interest coincide with each other, as regions for deriving flare characteristics, but the present invention is not limited to this, and the number of regions to be determined may be three or more.

[0041] The extraction area determination unit 301 outputs the coordinates in the RIP image data of each determined area (hereinafter, sometimes referred to as determined area coordinates) to the read value extraction unit 302. Note that the determined area coordinates may be any information as long as it is coordinate information that can identify the determined area, such as the upper left coordinates and lower right coordinates of the determined area.

[0042] The read value extraction unit 302 is a functional unit that extracts read values ​​of each area indicated by the determined area coordinates received from the extraction area determination unit 301 in the read image data read by the image reading device 14. That is, the read value extraction unit 302 extracts read values ​​of an area on the read image data that corresponds to an area (e.g., areas AR1 and AR2 shown in FIG. 7) determined in the RIP image data by the extraction area determination unit 301. Here, in the area of ​​the read image data extracted by the read value extraction unit 302, areas that correspond to the attention area and the peripheral area in the area in the RIP image data by the extraction area determination unit 301 are similarly referred to as the attention area and the peripheral area, respectively.

[0043] Here, the read values ​​of the regions of interest extracted by the read value extraction unit 302 do not necessarily match. This is because, as described above, differences may occur between the read values ​​of the regions of interest due to the influence of flare on the read image data. The read value extraction unit 302 outputs the read values ​​of each extracted region to the parameter calculation unit 303.

[0044] The parameter calculation unit 303 is a functional unit that calculates correction parameters for correcting color variations (reading variations) caused by the image reading device 14 contained in the read image data using the read values ​​of the area in the read image data extracted by the read value extraction unit 302.

[0045] Specifically, as shown in Fig. 8(a), the parameter calculation unit 303 identifies points P1 and P2 determined by the read value of the extracted region of interest and the read values ​​of the regions surrounding the region in a coordinate plane with the horizontal axis representing the read values ​​of the surrounding region and the vertical axis representing the read values ​​of the region of interest. Here, the read value of the region of interest may be any read value that represents the region of interest, such as the average, median, or mode of the read values ​​constituting the region of interest. The same applies to the read values ​​of the surrounding region.

[0046] Then, as shown in FIG. 8B, the parameter calculation unit 303 calculates a straight line by linear interpolation for points P1 and P2, and identifies points Pmin and Pmax when the minimum read value (read value is 0 (black)) and the maximum read value (read value is 255 (white)) of the surrounding area on the straight line are located. Here, the linear interpolation for points P1 and P2 refers to linear interpolation of the read values ​​of the attention area corresponding to the read values ​​of the surrounding area in the read image data. Then, the parameter calculation unit 303 calculates correction parameters for performing flare correction on the read image data using the difference between the read values ​​of the attention area at the identified points Pmin and Pmax. That is, the parameter calculation unit 303 estimates the read values ​​of the attention area corresponding to the minimum read value and the maximum read value of the surrounding area, respectively, using the linearly interpolated straight line, and calculates correction parameters based on the difference between the estimated read values. The parameter calculation unit 303 outputs the calculated correction parameters to the correction parameter update unit 202. In addition, if the number of areas determined by the extraction area determination unit 301 is three or more, the number of points on the coordinate plane identified by the parameter calculation unit 303 will also be the same, so the parameter calculation unit 303 may calculate a straight line by linear interpolation of these points.

[0047] The correction parameter update unit 202 is a functional unit that determines whether or not to update already applied correction parameters using the correction parameters calculated by the correction parameter generation unit 201. If there are already applied correction parameters, the correction parameter update unit 202 displays an update selection screen 1000 as shown in Fig. 9 on the touch panel 16 (touch panel 507).

[0048] The update selection screen 1000 is a screen that allows the user to select whether or not to update the correction parameters via the touch panel 16 (an example of an input unit). The update selection screen 1000 includes an update button 1001 and a maintain button 1002, as shown in FIG.

[0049] The update button 1001 is a button for updating the correction parameters. The maintain button 1002 is a button for selecting to continue using the correction parameters that have already been applied without updating the correction parameters.

[0050] Details of the correction parameter update process by the correction parameter update unit 202 will be described later. When updating the correction parameters (when the update button 1001 in FIG. 9 is pressed), the correction parameter update unit 202 updates and stores the correction parameters in the auxiliary storage device 505 using the correction parameters calculated by the correction parameter generation unit 201, and outputs the updated correction parameters to the read image correction processing unit 203.

[0051] The correction parameters updated by the correction parameter update unit 202 are not limited to those selected by the user manually through the update selection screen 1000. For example, if there are correction parameters that have already been applied, the correction parameter update unit 202 may automatically update the correction parameters with the correction parameters calculated by the correction parameter generation unit 201.

[0052] Furthermore, correction parameters may be managed for each printing paper type, and may be viewed, edited, and deleted by the user, as in a correction parameter editing screen 1100 shown in Fig. 10. The correction parameter updating unit 202 displays the correction parameter editing screen 1100 on the touch panel 507 in response to a user's operation on the touch panel 507. As shown in Fig. 10, the correction parameter editing screen 1100 includes a correction parameter display area 1101, an edit button 1102, a delete button 1103, and a close button 1104.

[0053] The correction parameter display area 1101 is an area including, for each printing paper, a "Media" column indicating the printing paper, a "Selected" column for selecting the object to be edited, "Parameters" for displaying and editing the correction parameters, and "Date" indicating the update date. The edit button 1102 is a button for updating (storing) the correction parameters edited in the correction parameter display area 1101. The delete button 1103 is a button for deleting the correction parameter selected in the "Selected" column. The close button 1104 is a button for closing the correction parameter editing screen 1100.

[0054] This allows the correction parameter update unit 202 to edit the correction parameters for each printing paper in response to a user's operation on the correction parameter editing screen 1100 via the touch panel 16.

[0055] The correction parameters may be viewed and edited on the correction parameter editing screen 1100 even when the image forming apparatus 13 is not in the middle of a printing operation.

[0056] The read image correction processing unit 203 is a functional unit that corrects the read image data for color variations caused by the image reading device 14, using the correction parameters received from the correction parameter update unit 202. The read image correction processing unit 203 outputs the corrected read image data generated by the correction to the color variation correction unit 102.

[0057] Image forming device 13 forms an image using color variation correction values ​​calculated by color variation correction unit 102 based on the RIP image data output from print server 3. Then, image forming device 13 outputs printed paper PS (print manuscript) on which the image has been formed. Printed paper PS is transported to image reading device 14 at a downstream stage by transport belt 12 shown in FIG. 1.

[0058] The image reading device 14 performs a reading operation on the printed paper PS transported by the transport belt 12, and obtains image read data of the printed paper PS. Then, the image reading device 14 outputs the image read data to the image processing device 10.

[0059] The above-described functional configuration of the image processing device 10 makes it possible to calculate, in real time, correction parameters for correcting color variations in read image data caused by the image reading device 14. For example, if the printed paper PS is read by the image reading device 14 a long time after the image is formed on the printed paper PS, the corrected read image data generated by the read variation correction unit 103 may not be able to appropriately correct the color variations caused by the image forming device 13 due to changes over time in the operating conditions of the image forming system 1 (e.g., the operating conditions of the image forming device 13, etc.). In contrast, in the image forming system 1 according to this embodiment, the printed paper PS on which the image is formed by the image forming device 13 is conveyed on the conveyor belt 12 toward the image reading device 14, where it is read by the image reading device 14 to generate read image data, and the above-described correction parameters are generated from the read image data. As a result, color variation correction unit 102 can calculate a color variation correction value that can appropriately correct color variations caused by image forming device 13, and image forming device 13 performs image formation operations using this color variation correction value, thereby achieving color stability control. That is, by using image data read by image reading device 14 for printed paper PS on which an image has been formed by image forming device 13, color variations caused by image reading device 14 based on reading variations such as flare can be corrected in real time, and further color variations caused by image forming device 13 can be appropriately corrected. This makes it unnecessary to use a reference chart printed in advance.

[0060] 4 to 6 are realized by, for example, executing a program by the CPU 501 shown in Fig. 3. At least some of the functional units of the image processing device 10 shown in Fig. 4 to 6 may be realized by hardware such as an integrated circuit, or may be realized by a combination of software and hardware.

[0061] Furthermore, the functional units of the image processing device 10 shown in Figures 4 to 6 are conceptual representations of functions, and are not limited to such configurations. For example, the multiple functional units illustrated as independent functional units in the image processing device 10 shown in Figures 4 to 6 may be configured as a single functional unit. On the other hand, the function of a single functional unit in the image processing device 10 shown in Figures 4 to 6 may be divided into multiple units and configured as multiple functional units. Furthermore, the functional units of the image processing device 10 do not need to be configured as distinct software modules as blocks shown in Figures 4 to 6, and it is sufficient that the functions of the functional units as a whole are realized by executing a program in the image processing device 10.

[0062] (Flow of the process of updating correction parameters of the image processing device) 11 is a flowchart showing an example of the flow of the correction parameter update process of the image processing device 10 according to the embodiment. The flow of the correction parameter update process of the image processing device 10 according to the embodiment will be described with reference to FIG.

[0063] <Step S11> The correction parameter generation unit 201 of the read variation correction unit 103 of the image processing device 10 calculates and generates correction parameters for correcting color variations caused by the image reading device 14, which are included in the read image data, using the RIP image data generated by the print server 3 and the read image data obtained by the image reading device 14 reading operation on the printed paper PS. The correction parameter generation unit 201 outputs the generated correction parameters to the correction parameter update unit 202. Then, the process proceeds to step S12.

[0064] <Step S12> The correction parameter update unit 202 of the read variation correction unit 103 of the image processing device 10 determines whether or not the correction parameters to be applied to the correction processing in the read image correction processing unit 203 have already been generated (whether or not the correction parameters have already been stored in the auxiliary storage device 505). If the correction parameters have already been generated (step S12: Yes), the process proceeds to step S13, and if they have not been generated (step S12: No), the process proceeds to step S14.

[0065] <Step S13> The correction parameter update unit 202 displays an update selection screen 1000 on the touch panel 16 (touch panel 507). Then, the correction parameter update unit 202 determines whether or not the user has pressed the update button 1001 on the update selection screen 1000 (whether or not to update the correction parameters). If the update button 1001 has been pressed (if the correction parameters are to be updated) (step S13: Yes), the process proceeds to step S14, and if the maintain button 1002 has been pressed (step S13: No), the image processing device 10 ends the correction parameter update process.

[0066] <Step S14> The correction parameter update unit 202 updates and stores the correction parameters calculated by the correction parameter generation unit 201 in the auxiliary storage device 505. Then, the image processing device 10 ends the correction parameter update process.

[0067] As described above, in the image processing device 10 according to this embodiment, the extraction area determination unit 301 determines a plurality of target areas to be used for correcting reading variations such as flare in the document image data (RIP image data) of the printed paper PS formed by the image forming device 13, the parameter calculation unit 303 calculates correction parameters for correcting reading variations for the read image data based on read values ​​of areas corresponding to the respective target areas determined by the extraction area determination unit 301 in the read image data read by the image reading device 14 for the printed paper PS, and the read image correction processing unit 203 corrects the read image data using the correction parameters calculated by the parameter calculation unit 303. This makes it possible to realize appropriate control of the image forming operation of the image forming device 13 by correcting for reading variations using the printed image (printed paper PS) without using a dedicated chart.

[0068] Furthermore, in the image processing device 10 according to this embodiment, when correction parameters already exist when the parameter calculation unit 303 calculates the correction parameters, if an operation to select update is performed via the touch panel 16, the correction parameter update unit 202 updates the already existing correction parameters (correction parameters already stored in the auxiliary storage device 505) with the correction parameters newly calculated by the parameter calculation unit 303. This allows the user to decide whether or not to update the correction parameters when the correction parameters have already been applied.

[0069] The program executed by the image processing device 10 of the above-described embodiment may be configured to be provided by being pre-installed in a ROM or the like. The program executed by the image processing device 10 of the above-described embodiment may also be configured to be provided as a computer program product by being recorded in an installable or executable file format on a computer-readable recording medium such as a CD-ROM (Compact Disc Read Only Memory), a flexible disk (FD), a CD-R (Compact Disk-Recordable), or a DVD (Digital Versatile Disk). The program executed by the image processing device 10 of the above-described embodiment may also be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. The program executed by the image processing device 10 of the above-described embodiment may also be provided or distributed via a network such as the Internet.

[0070] Furthermore, the program executed by the image processing device 10 of the above-described embodiment has a modular structure including each of the functional units described above, and in terms of actual hardware, the CPU 501 reads and executes the program from the ROM 502 or the auxiliary storage device 505, thereby loading each of the functional units described above onto the main storage device (RAM 503), and each functional unit is generated on the main storage device (RAM 503).

[0071] The aspects of the present invention are as follows. <1> an area determination unit that determines a plurality of target areas to be used for correcting reading variations in document image data of a print document imaged by an image forming apparatus; a calculation unit that calculates correction parameters for correcting the reading fluctuations of the read image data based on read values ​​of areas corresponding to the target areas determined by the area determination unit in the read image data read by an image reading device of the print document; and a first correction unit that corrects the read image data using the correction parameters calculated by the calculation unit; The image processing device is provided with: <2> The image forming apparatus further includes a second correction unit that calculates a correction value to be applied to image formation by the image forming apparatus by comparing the read image data corrected by the first correction unit with document image data of the print document. <1> 2 is an image processing device according to the first embodiment. <3> the target region is composed of a region of interest of a predetermined size and a peripheral region surrounding the region of interest, the region determination unit determines the plurality of target regions in which the read values ​​of the attention regions match each other in the document image data of the print document; the calculation unit calculates the correction parameters based on a variation in read values ​​of each region corresponding to a region of interest in the plurality of target regions in the read image data. <1> or <2> 2 is an image processing device according to the first embodiment. <4> the calculation unit estimates read values ​​of the region corresponding to the region of interest that correspond to maximum and minimum read values ​​that can be taken as read values ​​of the region corresponding to the peripheral region in the read image data by linear interpolation of read values ​​of each region corresponding to the region of interest that corresponds to read values ​​of each region corresponding to the peripheral region in the read image data, and calculates the correction parameter based on a difference between the estimated read values. <3> 2 is an image processing device according to the first embodiment. <5> When the calculation unit calculates the correction parameters, if the correction parameters already exist, an update unit updates the existing correction parameters with the correction parameters newly calculated by the calculation unit. <1> ~ <4> 10. The image processing device according to claim 9, wherein: <6> When a correction parameter already exists when the calculation unit calculates the correction parameter, if an operation for selecting update is performed via an input unit, the update unit updates the already existing correction parameter with the correction parameter newly calculated by the calculation unit. <5> 2 is an image processing device according to the first embodiment. <7> The correction parameters are managed in a storage device for each sheet of paper, 7. The image processing device according to claim 5, wherein the update unit enables editing of the correction parameters for each sheet of paper in response to an operation via an input unit. <8> an image forming apparatus that forms an image on a printing paper from document image data and outputs a print document; an image reading device that reads the print document on which an image has been formed by the image forming device; an image processing device including: an area determination unit that determines a plurality of target areas to be used for correcting reading variations in the document image data; a calculation unit that calculates correction parameters for correcting the reading variations for the read image data based on read values ​​of areas corresponding to the respective target areas determined by the area determination unit in the read image data read from the print document by an image reading device; and a first correction unit that corrects the read image data using the correction parameters calculated by the calculation unit; The image forming system has the following features. <9> The image reading device is disposed downstream of the image forming device in a transport path along which the print document is transported. <8> 2. The image forming system according to claim 1, wherein: <10> The image reading device performs a reading operation on the print document that is conveyed by a conveying device and on which an image is formed by the image forming device. <9> 2. The image forming system according to claim 1, wherein: <11> an area determination step of determining a plurality of target areas to be used for correcting reading variations in document image data of a print document imaged by an image forming apparatus; a calculation step of calculating correction parameters for correcting the reading fluctuations for the read image data based on read values ​​of regions corresponding to the determined target regions in the read image data read by an image reading device for the print document; a correction step of correcting the read image data using the calculated correction parameters; The image processing method has the following features. <12> On the computer, an area determination step of determining a plurality of target areas to be used for correcting reading variations in document image data of a print document imaged by an image forming apparatus; a calculation step of calculating correction parameters for correcting the reading fluctuations for the read image data based on read values ​​of regions corresponding to the determined target regions in the read image data read by an image reading device for the print document; a correction step of correcting the read image data using the calculated correction parameters; This is a program for executing the above. [Explanation of symbols]

[0072] 1. Image forming system 2. User PC 3 Print Server 10 Image processing device 11 Paper tray 12 conveyor belt 13 Image forming device 14 Image reader 15 Paper output tray 16 Touch Panel 101 Image processing unit 102 Color Fluctuation Correction Unit 103 Reading fluctuation correction unit 201 Correction parameter generation unit 202 Correction parameter update unit 203 Read image correction processing unit 301 Extraction area determination section 302 Reading value extraction unit 303 Parameter Calculation Unit 501 CPU 502 ROM 503 RAM 505 Auxiliary storage 506 Network I / F 507 Touch Panel 510 Bus Line 1000 Update Selection Screen 1001 Update button 1002 Maintain button 1100 Correction parameter editing screen 1101 Correction parameter display area 1102 Edit button 1103 Delete button 1104 Close button AA1, AA2 Areas of Interest AA11, AA12 Areas of Interest AR1, AR2 area AR11, AR12 area DC dedicated chart P Print paper P1 and P2 points P11, P12 points Pmax and Pmin points PS pre-printed paper Areas surrounding SA1 and SA2 SA11, SA12 surrounding area [Prior art documents] [Patent documents]

[0073] [Patent Document 1] Japanese Patent Application Publication No. 2019-149635 [Patent Document 2] Japanese Patent Publication No. 2020-010306

Claims

1. an area determination unit that determines a plurality of target areas to be used for correcting reading variations in document image data of a print document imaged by an image forming apparatus; a calculation unit that calculates correction parameters for correcting the reading fluctuations of the read image data based on read values ​​of areas corresponding to the target areas determined by the area determination unit in the read image data read by an image reading device of the print document; and a first correction unit that corrects the read image data using the correction parameters calculated by the calculation unit; An image processing device comprising:

2. 2. The image processing device according to claim 1, further comprising a second correction unit that calculates a correction value to be applied to image formation by the image forming device by comparing the read image data corrected by the first correction unit with the original image data of the print original.

3. the target region is composed of a region of interest of a predetermined size and a peripheral region surrounding the region of interest, the region determination unit determines the plurality of target regions in which the read values ​​of the attention regions match each other in the document image data of the print document; The image processing apparatus according to claim 1 , wherein the calculation unit calculates the correction parameters based on a variation in read values ​​of each region corresponding to a region of interest in the plurality of target regions in the read image data.

4. 4. The image processing device according to claim 3, wherein the calculation unit estimates the read values ​​of the region corresponding to the region of interest that correspond to the maximum read value and the minimum read value that can be taken as the read values ​​of the region corresponding to the surrounding region in the read image data by linear interpolation of the read values ​​of each region corresponding to the region of interest that corresponds to the read values ​​of each region corresponding to the surrounding region in the read image data, and calculates the correction parameter based on the difference between the estimated read values.

5. 3. The image processing device according to claim 1, further comprising: an update unit that, when the calculation unit calculates the correction parameters and, if the correction parameters already exist, updates the existing correction parameters with the correction parameters newly calculated by the calculation unit.

6. 6. The image processing device according to claim 5, wherein, when a correction parameter already exists when the calculation unit calculates the correction parameter, and an operation to select update is performed via an input unit, the update unit updates the already existing correction parameter with the correction parameter newly calculated by the calculation unit.

7. The correction parameters are managed in a storage device for each sheet of paper, The image processing apparatus according to claim 5 , wherein the update unit enables editing of the correction parameters for each sheet in response to an operation via an input unit.

8. an image forming apparatus that forms an image on a printing paper from document image data and outputs a print document; an image reading device that reads the print document on which an image has been formed by the image forming device; an image processing device including: an area determination unit that determines a plurality of target areas to be used for correcting reading variations in the document image data; a calculation unit that calculates correction parameters for correcting the reading variations for the read image data based on read values ​​of areas corresponding to the respective target areas determined by the area determination unit in the read image data read from the print document by an image reading device; and a first correction unit that corrects the read image data using the correction parameters calculated by the calculation unit; An image forming system having:

9. 9. The image forming system according to claim 8, wherein the image reading device is disposed downstream of the image forming device on a transport path along which the print document is transported.

10. 10. The image forming system according to claim 9, wherein the image reading device performs a reading operation on the print document that has been conveyed by a conveying device and on which an image has been formed by the image forming device.

11. an area determination step of determining a plurality of target areas to be used for correcting reading variations in document image data of a print document imaged by an image forming apparatus; a calculation step of calculating correction parameters for correcting the reading fluctuations for the read image data based on read values ​​of regions corresponding to the determined target regions in the read image data read by an image reading device for the print document; a correction step of correcting the read image data using the calculated correction parameters; An image processing method comprising:

12. On the computer, an area determination step of determining a plurality of target areas to be used for correcting reading variations in document image data of a print document imaged by an image forming apparatus; a calculation step of calculating correction parameters for correcting the reading fluctuations for the read image data based on read values ​​of regions corresponding to the determined target regions in the read image data read by an image reading device for the print document; a correction step of correcting the read image data using the calculated correction parameters; A program to execute.

Images