Image processing device, image processing method, and program

Abstract

To save time and effort of a user in printing a plurality of correction charts and charts for stabilization, and performing automatic gradation correction by using the plurality of correction charts from the plurality of printed charts.SOLUTION: An image processing apparatus 100 first performs control for printing, on one recording medium, a plurality of chart images for correction and identification images for identifying the charge images for correction respectively for every chart image for correction, and control for printing chart image for stabilization on the recording medium before performing the control for printing the plurality of chart images for correction. The image processing apparatus subsequently, from a plurality of charts for correction in which the chart image for correction and the identification image are printed on every chart image for correction, and a plurality of scan images obtained by reading one or more charts for stabilization on which the chart images for stabilization are printed, based on the identification images captured in the scan images, specifies the scan images corresponding to the plurality of charts for correction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a tone conversion technique during image formation.

Background Art

[0002] There is an image forming apparatus such as a copying machine that performs digital processing on data of an image obtained by reading a document with a scanner (hereinafter referred to as a "scan image"), and prints the scan image data after digital processing with a printer. When the tone when forming an image on a recording medium such as printing paper with a printer in an image forming apparatus with such a configuration is not adjusted, the tonality of the image formed on the recording medium (hereinafter referred to as a "formed image") may be impaired. Further, in order to suppress the impairment of the tonality of the formed image, there is automatic tone correction as a technique for adjusting the tone of the formed image. The automatic tone correction reads an automatic tone correction chart (hereinafter referred to as a "correction chart") printed by the printer of the image forming apparatus with a scanner, and acquires the tone characteristics of the current printer based on the scan image obtained by the reading. Further, based on the acquired tone characteristics, a conversion table for converting the tone of the printed image is generated so that a predetermined tonality can be obtained in the formed image.

[0003] Patent Document 1 discloses the following technology. The technology disclosed in Patent Document 1 first involves sequentially scanning multiple correction charts placed in an automatic document feeder (ADF) using a scanner. Here, each of the multiple correction charts is for performing automatic gradation correction for a different purpose. Next, automatic gradation correction corresponding to each correction chart is performed using the multiple scanned images obtained by the scanner. According to the technology disclosed in Patent Document 1, by placing multiple correction charts in the ADF and having the scanner scan them sequentially, the user can perform multiple automatic gradation corrections for different purposes with a single operation command. Furthermore, Patent Document 2 discloses a technology in which a color stabilization chart (hereinafter referred to as "stabilization chart") that is not used for automatic gradation correction is printed immediately before printing the correction chart. According to the technology disclosed in Patent Document 2, by printing the stabilization chart immediately before printing the correction chart, the temperature of the fuser when printing the correction chart can be stabilized, thereby stabilizing the color of the correction chart. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-92034 [Patent Document 2] Japanese Patent Publication No. 2013-148863 [Overview of the project] [Problems that the invention aims to solve]

[0005] In the technology disclosed in Patent Document 1, each correction chart is used to perform different gradation corrections in automatic gradation correction. Therefore, when a stabilization chart is printed immediately before printing each correction chart, and these charts are sequentially scanned, the user needs to accurately select multiple correction charts from the printed charts. Furthermore, the user needs to have the scanner read the selected correction charts in a predetermined order. [Means for solving the problem]

[0006] The image forming apparatus is picture The statue mark print mark printing hand Steps and, A transport means for transporting printed materials printed by the printing means, and the transport means for transporting the printed materials Reading Reading means and A correction means for performing gradation correction, Having the print hand The steps are, After printing a first predetermined image on the first sheet without printing the first identification image, print the first identification image and the first tone correction chart on the second sheet, print the second predetermined image on the third sheet without printing the second identification image, print the second identification image and the second tone correction chart on the fourth sheet. , the above Read The means are, The first sheet, the second sheet, the third sheet, and the fourth sheet, which have been transported by the transport means, are read. , The correction means performs a first tone correction based on a first read identification image corresponding to the first identification image and a first read tone correction chart corresponding to the first tone correction chart, obtained by reading by the reading means, and performs a second tone correction based on a second read identification image corresponding to the second identification image and a second read tone correction chart corresponding to the second tone correction chart, obtained by reading by the reading means. . [Effects of the Invention]

[0007] According to this disclosure, when printing multiple correction charts and stabilization charts and performing automatic grayscale correction using multiple correction charts from among the printed charts, the effort required of the user can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing an example of a functional block of an image processing apparatus according to Embodiment 1. [Figure 2] This is a block diagram showing an example of the hardware configuration of an image processing device according to the first embodiment. [Figure 3] This is an external view showing an example of the external appearance of an image forming apparatus according to Embodiment 1. [Figure 4] This is a side cross-sectional view showing an example of the internal structure of a scanner according to Embodiment 1. [Figure 5] This figure shows an example of a GUI screen displayed on the display unit of the image processing apparatus according to Embodiment 1. [Figure 6] This figure shows an example of the configuration of the correction chart and stabilization chart output from the printer when automatic grayscale correction is performed according to Embodiment 1. [Figure 7] This flowchart shows an example of the processing flow from the image processing device according to Embodiment 1 to the point where it outputs multiple correction charts and stabilization charts to a printer. [Figure 8] This flowchart shows an example of the processing flow in the image processing device according to Embodiment 1, from reading multiple correction charts and stabilization charts to generating (updating) a conversion table. [Figure 9] This figure shows an example of a correction chart and a stabilization chart output from a printer when automatic grayscale correction is performed in the image processing device according to Embodiment 2. [Figure 10] This figure shows an example of the overlap of the chart bundles when the correction chart and stabilization chart, which are output from the printer by print control using the image processing device according to Embodiment 2, are placed in the document tray. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described in detail below with reference to the attached drawings. Note that the following embodiments are not intended to limit the scope of the claims of this disclosure, and not all combinations of features described in the embodiments are necessarily essential to the solutions of this disclosure.

[0010] <Embodiment 1> Referring to FIGS. 1 to 8, the image processing apparatus 100 according to Embodiment 1 will be described. FIG. 1 is a block diagram showing an example of the functional blocks of the image processing apparatus 100 according to Embodiment 1. The image processing apparatus 100 includes a print control unit 101, an acquisition unit 102, and a generation unit 103. The processing of each unit included in the image processing apparatus 100 is performed by hardware such as an ASIC (Application Specific Integrated Circuit) built into the image processing apparatus 100. The processing may be performed by hardware such as an FPGA (Field Programmable Gate Array). Further, the processing may be performed by software using a memory such as a RAM (Random Access Memory) and a processor such as a CPU (Central Processor Unit). Details of the processing of each unit of the functional blocks shown in FIG. 1 will be described later.

[0011] Referring to FIG. 2, the hardware configuration of the image processing apparatus 100 when each unit of the functional blocks included in the image processing apparatus 100 according to the first embodiment operates as software will be described. FIG. 2 is a block diagram showing an example of the hardware configuration of the image processing apparatus 100 according to the first embodiment. The image processing apparatus 100 is configured by a computer, and the computer has a CPU 201, a ROM 202, a RAM 203, an auxiliary storage device 204, a display unit 205, an operation unit 206, a communication unit 207, and a bus 208 as shown as an example in FIG. 2.

[0012] The CPU 201 is a processor that controls the computer by using programs or data stored in the ROM 202, the RAM 203, etc., causing the computer to function as each part of the functional blocks included in the image processing apparatus 100 shown in FIG. 1. Note that the image processing apparatus 100 has one or more dedicated hardware different from the CPU 201, and at least a part of the processing by the CPU 201 may be executed by the dedicated hardware. Examples of the dedicated hardware include an ASIC, an FPGA, and a DSP (Digital Signal Processor). The ROM 202 is a memory that stores programs etc. that do not require modification. The RAM 203 is a memory that temporarily stores programs or data supplied from the auxiliary storage device 204, or data etc. supplied from the outside via the communication unit 207. The auxiliary storage device 204 is constituted by, for example, a hard disk drive, and stores various data such as image data or audio data.

[0013] The display unit 205 is constituted by, for example, a liquid crystal display or an LED, etc., and displays a GUI (Graphical User Interface) etc. for the user to operate the image processing apparatus 100 or view the state of processing in the image processing apparatus 100. The operation unit 206 is constituted by, for example, a keyboard, a mouse, a joystick, or a touch panel, etc., and receives an operation by the user and inputs various instructions to the CPU 201. The CPU 201 also operates as a display control unit that controls the display unit 205 and an operation control unit that controls the operation unit 206.

[0014] The communication unit 207 is used for communication such as sending and receiving data between the image processing device 100 and external devices. For example, if the image processing device 100 is connected to an external device by wire, a communication cable is connected to the communication unit 207. If the image processing device 100 has a function to communicate wirelessly with an external device, the communication unit 207 is equipped with an antenna. The bus 208 connects the various parts of the image processing device 100 to transmit information. In the first embodiment, the display unit 205 and the operation unit 206 are described as being located inside the image processing device 100, but at least one of the display unit 205 and the operation unit 206 may be located outside the image processing device 100 as a separate device.

[0015] As shown in Figure 1, for example, the image processing apparatus 100 is applied to the image forming apparatus 1. The image forming apparatus 1 is a device composed of a multifunction printer (MFP) or the like, and includes a printer 140, a scanner 130, and the image forming apparatus 100. The printer 140 and the scanner 130 are connected to the image processing apparatus 100 via a communication unit 207. The printer 140 receives print image data output from the image processing apparatus 100 and prints the print image onto a recording medium such as printing paper. The scanner 130 optically reads the original document (hereinafter referred to as "scanning"). The scanner 130 outputs the image data (hereinafter referred to as "scan image data") obtained by scanning the original document (hereinafter referred to as "scanned image") to the image processing apparatus 100.

[0016] The printer 140 and scanner 130 will be described with reference to Figures 3 and 4. Figure 3 is an external view showing an example of the external appearance of the image forming apparatus 1 according to Embodiment 1. The image processing apparatus 100 is housed inside, for example, the housing 320. In the image forming apparatus 1 shown as an example in Figure 3, the scanner 130 is located above the printer 140. The paper feed cassette 301 stores recording media such as printing paper. The image forming apparatus 1 shown in Figure 3 has three paper feed cassettes 301 as an example, but the number of paper feed cassettes 301 is not limited to three. The transport roller 302 feeds the recording media stored in the paper feed cassette 301 to the printing unit 303. At this time, if the paper overlap amount described later is set, the paper is transported at the timing when a part of the recording media of the current page overlaps with the recording media of the previous page.

[0017] The printing unit 303 prints an image onto the fed recording medium. The printing unit 303 may be an inkjet type that prints an image by spraying ink onto the recording medium, or an electrophotographic type that prints an image by fixing toner onto the recording medium. The recording medium printed by the printing unit 303 is discharged to the output tray 305 via the transport roller 304. In the case of double-sided printing, the recording medium is first sent to the output tray 308 via the feed rollers 306 and 307 instead of the feed roller 304, and then sent to the double-sided printing transport path 310 by the reverse-rotating feed rollers 307 and 309. Next, the recording medium is transported to the transport roller 311 and returns to the printing unit 303. The stapling device 312 staples the recording medium output to the output tray 305.

[0018] Figure 4 is a side cross-sectional view showing an example of the internal structure of the scanner 130 according to Embodiment 1. The document tray 400 is a tray for loading documents to be scanned (hereinafter simply referred to as "documents"). The document tray 400 is equipped with a document sensor 402 for detecting whether or not documents are loaded on the document tray 400, two document guides 401, and a detection sensor 403 for detecting the size of the documents. The document guides 401 are arranged side by side in the vertical direction of the document (a direction perpendicular to the document transport direction on the plane in which the documents are placed). Documents loaded on the document tray 400 are transported by three rollers: a pickup roller 404, a transport roller 406, and a paper output roller 409. The pickup roller 404 is a roller for transporting documents loaded on the document tray 400 to the document transport path. The transport roller 406 transports the document that has been transported into the document transport path by the pickup roller 404, and the output roller 409 transports the document that has been transported by the transport roller 406 to the output tray 410.

[0019] The document transported by the pickup roller 404 is detected by a detection sensor 405 that detects the passage of the document, and based on the result of the detection, it is determined whether or not the document has completed its passage. The transport roller 406, the pickup roller 404, and the paper output roller 409 are driven by, for example, a stepping motor (not shown in Figure 4). The ADF (Auto Document Feeder) unit is composed of the document tray 400, document guide 401, document sensor 402, detection sensors 403, 405, pickup roller 404, transport roller 406, paper output roller 409, and paper output tray 410.

[0020] Sub-scanning decimation in the ADF unit is achieved by doubling the frequency of the drive pulses of the stepping motors that drive the transport roller 406, pickup roller 404, and paper output roller 409. When a document transported by the ADF unit passes over the top of the reading window 407, it is scanned by a CIS (Contact Image Sensor) 408 provided in a sensor unit 411 located below the reading window 407. The sensor unit 411 can move freely in the sub-scanning direction and can also move in the same direction as the transport direction of the document being transported from the transport roller 406 towards the paper output roller 409. The reading window 407 has a certain length in the sub-scanning direction, and within that length, the CIS 408 can be moved to any position and the document can be read at the new position.

[0021] The CIS408 is composed of photoelectric conversion elements such as a CCD (Charge Coupled Device). The CIS408 also performs FIFO (First in First out) processing to store image data read by each photoelectric conversion element, and generates control signals to control the FIFO processing and the photoelectric conversion elements. The CIS408 is generally realized by arranging multiple photoelectric conversion elements in a line. The sensor unit 411 is also provided with a light source (not shown) to illuminate the document through the reading window 407 or the document glass reading window 412, and generally, multiple light sources are arranged in a line. The light source is generally composed of an LED (Light-Emitting Diode), but is not limited to an LED. When the user places a document on the document glass instead of the document tray 400, the sensor unit 411 is moved to the bottom of the document glass reading window 412, and the document is scanned by the CIS408 through the reading window 412 while the sensor unit 411 is moved in the sub-scanning direction.

[0022] The processing of each part of the functional block of the image processing device 100 shown in Figure 1 will be explained. The print control unit 101 controls the printing (formation) of the print image onto the recording medium. Specifically, it outputs the print image data to the printer 140 via the communication unit 207 and controls the printer 140 to print the print image onto the recording medium. More specifically, the print control unit 101 controls the printing of multiple correction chart images, each with a different purpose for automatic gradation correction, onto one recording medium for each correction chart image. In addition, the print control unit 101 controls the printing of a stabilization chart image onto the recording medium to stabilize the printing of the multiple correction chart images.

[0023] Here, automatic tone correction refers to the process of generating or correcting conversion tables, such as lookup tables, for converting tones when generating a halftone pattern by performing image processing such as error diffusion processing and screen processing on a scanned image. In general, automatic tone correction requires the generation or correction of conversion tables corresponding to each of multiple image processing steps, such as error diffusion processing and screen processing. That is, multiple correction chart images with different purposes for automatic tone correction are images used to generate or correct conversion tables corresponding to each of multiple different image processing steps, such as error diffusion processing or screen processing, through automatic tone correction. Furthermore, stabilizing the printing of correction chart images means, for example, stabilizing the color of the image formed on the recording medium when the correction chart images are printed on the recording medium. Specifically, if the printer 140 is an electrophotographic type, stabilizing the printing of correction chart images means, for example, stabilizing the temperature of the fuser (not shown) provided by the printer 140. Furthermore, if the printer 140 is an inkjet type, stabilizing the printing of the correction chart image means, for example, eliminating or reducing nozzle clogging (not shown).

[0024] Before controlling the printing of each correction chart image, the print control unit 101 controls the printing of a stabilizing chart image onto the recording medium to stabilize the printing of each correction chart image. If, after controlling the printing of the nth (where n is an integer greater than or equal to 1)th correction chart image, the (n+1)th correction chart image can be stably printed, the print control unit 101 may perform the following control. For example, in this case, the print control unit 101 performs the control for printing the (n+1)th correction chart image immediately following the control for printing the nth correction chart image. That is, in this case, the print control unit 101 may omit the control for printing the stabilizing chart image onto the recording medium before controlling the printing of the (n+1)th correction chart image. The printer 140 prints the correction chart image and the stabilizing chart image onto the recording medium based on the control by the print control unit 101. Hereinafter, the recording medium on which the correction chart image is printed will be referred to as the correction chart, and the recording medium on which the stabilizing chart image is printed will be referred to as the stabilizing chart.

[0025] Furthermore, before controlling the printing of the correction chart image, the print control unit 101 controls the printing of stabilization chart images on a predetermined number of recording media (hereinafter referred to as the "specified number of outputs"). In this case, the printer 140 prints the specified number of stabilization charts before each correction chart is printed. Note that if the print control unit 101 controls the printing of the nth correction chart image followed by the (n+1)th correction chart image, the printer 140 will print the (n+1)th correction chart immediately after the nth correction chart.

[0026] Here, the number of specified outputs is determined, for example, based on user input. The number of specified outputs may be initially set to the number of stabilization chart images required to achieve a stable state for printing correction chart images. Referring to Figure 5, the configuration in which the number of specified outputs is determined by user input will be explained. Hereafter, the operation unit 206 is configured as a touch panel, and the user will be described as performing input operations by touching the GUI screen displayed on the display unit 205.

[0027] Figure 5 shows an example of a GUI screen displayed on the display unit 205 of the image processing device 100 according to Embodiment 1. Specifically, Figure 5(a) shows an example of a GUI screen for setting automatic gradation correction displayed on the display unit 205 according to Embodiment 1. The user sets the automatic gradation correction and issues an instruction to start the execution of automatic gradation correction by referring to the GUI screen shown as an example in Figure 5(a) and performing input operations.

[0028] Button 501 is an input button for selecting the category of recording medium to which automatic gradation correction will be performed. In the following explanation, the printer 140 will be described as an electrophotographic type. Generally, electrophotographic printers print well by switching the printing speed according to the basis weight of the recording medium. Furthermore, optimal gradation conversion is possible by switching the conversion table referenced for gradation conversion of the scanned image for each printing speed. Therefore, the conversion table is stored in the auxiliary storage device 204 in association with information indicating the printing speed. The print control unit 101 reads the conversion table into the RAM 203 when the image forming apparatus 1 is started or when printing, and uses it for gradation conversion processing of the print image when controlling the printing of the print image onto the recording medium.

[0029] The user presses button 501 to select the category of recording medium for which automatic gradation correction is to be performed, thereby instructing the system to generate or update the conversion table used at the corresponding printing speed for that recording medium. Note that button 501 is not a mandatory component in the GUI screen shown in Figure 5(a) and can be omitted. In this case, for example, the image processing device 100 may be configured to reflect the results of the automatic gradation correction in the conversion table corresponding to each printing speed. Furthermore, pressing an input button as used herein is not limited to actually pressing the input button; for example, touching the area on the GUI screen where the input button is displayed with a finger or stylus may also be used.

[0030] Button 502 is an input button used to instruct the user to start automatic grayscale correction. The operation after button 502 is pressed by the user will be described later. Button 503 is an input button used to transition to a GUI screen for specifying the number of output stabilization charts. When button 503 is pressed by the user, the display transitions to a GUI screen for specifying the number of output stabilization charts. The GUI screen for specifying the number of output stabilization charts will be described later. Button 504 is an input button used to initialize the conversion values ​​listed in the conversion table back to their initial values. If automatic grayscale correction is performed when the conversion values ​​in the conversion table have become clearly abnormal for some reason, an appropriate conversion table may not be obtained. The user can reset the conversion values ​​in the conversion table to their initial values ​​by pressing button 504.

[0031] Button 505 is an input button for exiting without performing automatic tone correction. The GUI screen shown in Figure 5(a) is merely an example, and the GUI screen for setting automatic tone correction may include input buttons not shown in Figure 5(a), such as the following. For example, it is an input button for instructing whether to place the correction chart and stabilization chart on the document glass and have them read, or to place the correction chart and stabilization chart on the document tray 400 of the ADF and have them read. It is also an input button for instructing other methods of automatic tone correction, such as outputting tone patches within the image forming apparatus 1 and reading the output tone patches with the color sensor within the image forming apparatus 1.

[0032] Figure 5(b) shows an example of a GUI screen displayed on the display unit 205 according to Embodiment 1 for specifying the number of stabilization charts to be output when performing automatic grayscale correction.

[0033] Button 506 is an input button for setting the number of stabilization charts to be printed. If the set number of outputs is 0, when automatic tone correction is started, the stabilization chart will not be printed, and only the correction chart will be printed. If the set number of outputs is m (where m is a positive integer), when automatic tone correction is started, m stabilization charts and 1 correction chart will be printed for each correction chart image, for a total of m+1 charts. In other words, in this case, m+1 charts corresponding to the correction chart image will be considered as one set, and printing will be repeated for all correction chart images.

[0034] Button 507 is an input button that determines the number of outputs set using button 506 as the specified number of outputs. The value of the specified number of outputs is stored in RAM 203. After button 507 is pressed, the display transitions to the GUI screen shown in Figure 5(a). Button 508 is an input button that transitions the display to the GUI screen shown in Figure 5(a) without determining the number of outputs set using button 506 as the specified number of outputs.

[0035] In the GUI screen shown in Figure 5(a), when button 502 is pressed by the user, automatic gradation correction is initiated. Alternatively, after button 502 is pressed by the user, the system may acquire paper feed information indicating the type of recording medium to be used for printing the chart before starting the automatic gradation correction. Specifically, for example, after button 502 is pressed by the user, the display may transition to a GUI screen (not shown in Figure 5) for selecting one of the multiple paper feed cassettes 301 that contains the recording medium to be used for printing the chart. In this case, automatic gradation correction is initiated after the user selects the paper feed cassette 301. Once automatic gradation correction is initiated, the print control unit 101 controls the printing of all correction chart images and stabilization chart images to the recording medium, and the printer 140 prints all correction charts and stabilization charts. After the print control unit 101 has completed the print control for all correction chart images and stabilization chart images, the display unit 205 displays a GUI screen (not shown in Figure 5) for accepting input operations to start loading the charts.

[0036] Referring to Figure 6, the correction charts 610, 620 and the stabilization charts 611, 621 will be described. Figure 6 is a diagram showing an example of the configuration of the correction charts 610, 620 and the stabilization charts 611, 621 output from the printer 140 when automatic grayscale correction according to Embodiment 1 is performed. Note that the configuration of the correction charts 610, 620 and the stabilization charts 611, 621 shown in Figure 6 is an example where two correction chart images with different purposes for automatic grayscale correction are printed on the recording medium, and the specified number of outputs is 2. In addition, although the printed sides of the correction charts 610, 620 and the stabilization charts 611, 621 are facing towards the viewer in Figure 6, in reality, the correction charts 610, 620 and the stabilization charts 611, 621 are output from the printer 140 with the front and back facing in the opposite direction to that shown in Figure 6.

[0037] If the specified number of outputs is 2, as shown in Figure 6, first, two copies of the first stabilization chart 611 are printed and output from the printer 140, followed by one copy of the first correction chart 610, which is then output from the printer 140. Next, two copies of the second stabilization chart 621 are printed and output from the printer 140, and finally, one copy of the second correction chart 620 is printed and output from the printer 140. As a result, six charts are output in an overlapping state. The first correction chart 610 is, for example, used to generate or update a conversion table corresponding to error diffusion processing, and the second correction chart 620 is, for example, used to generate or update a conversion table corresponding to screen processing. Furthermore, the stabilization chart 611 and the stabilization chart 621 may be of different forms or of similar forms.

[0038] As shown in Figure 6 as an example, the multiple stabilization charts 611, 621 and the two correction charts 610, 620 are output from the printer 140 in an overlapping state. Therefore, it is inconvenient for the user to extract only the correction charts and place them in the document tray 400 of the ADF unit. For convenience, it is desirable to place all of the multiple stabilization charts 611, 621 and the two correction charts 610, 620 in the document tray 400 of the ADF unit in the overlapping state they were output from the printer 140.

[0039] The acquisition unit 102 acquires scanned image data. Specifically, the acquisition unit 102 acquires scanned image data by controlling the scanner 130 via the communication unit 207 to cause the scanner 130 to scan the document. More specifically, for example, the acquisition unit 102 controls the ADF unit via the communication unit 207 to sequentially transport one or more documents placed in the document tray 400 and have the scanner 130 scan them.

[0040] After all the charts have been printed from the printer 140, the user places the multiple charts, including the stabilization chart, printed from the printer 140 onto the document tray 400, maintaining the order in which they were printed. The acquisition unit 102 sequentially scans the multiple charts placed on the document tray 400 with the scanner 130 and acquires the scanned image data corresponding to each of the multiple charts in the order in which they were placed on the document tray 400. If the image forming apparatus 1 does not have an ADF unit, or if the user selects not to use the ADF unit via a GUI screen (not shown in Figure 5), the user sequentially places the multiple charts on the document glass and has each chart scanned by the scanner 130.

[0041] The generation unit 103 generates (updates) a conversion table for converting the grayscale of the scanned image. Specifically, it generates (updates) a conversion table corresponding to each correction chart based on each of the correction charts among the multiple scan image data corresponding to the multiple charts acquired by the acquisition unit 102.

[0042] More specifically, the generation unit 103 first identifies scan image data corresponding to each of the correction charts from among the multiple scan image data based on the specified number of outputs described above. For example, if the specified number of outputs is 2, and a chart bundle consisting of multiple charts, as shown as an example in Figure 6, is output from the printer 140, the generation unit 103 identifies scan image data corresponding to each of the correction charts as follows. In this case, the generation unit 103 first identifies the first two scan image data, counting from the first acquired scan image data, which correspond to the specified number of outputs, as stabilization charts. Then, it identifies the third scan image data as the scan image data corresponding to the first correction chart. Furthermore, it identifies the first two scan image data, counting from the fourth acquired scan image data, which correspond to the specified number of outputs, i.e., the fourth and fifth acquired scan image data, as stabilization charts. Then, it identifies the sixth scan image data as the scan image data corresponding to the second correction chart.

[0043] More generally, the generation unit 103 identifies the scan image data corresponding to the position obtained by multiplying the specified output number plus 1 by an arbitrary natural number as the scan image data corresponding to the correction chart. After identifying the scan image data corresponding to each correction chart, the generation unit 103 generates (updates) a conversion table using the identified scan image data. If the print control unit 101 controls the printing so that the (n+1)th correction chart is printed immediately after the nth correction chart, the generation unit 103 only needs to identify each of the multiple correction charts in the order of the charts output from the printer 140. A detailed explanation of the method for generating (updating) a conversion table for converting the gradation of the scan image using scan image data corresponding to multiple correction charts is omitted as it is well known.

[0044] The operation of the image processing device 100 will be described with reference to Figures 7 and 8. In the following description, "S" means step. Figure 7 is a flowchart showing an example of the processing flow from the image processing device 100 according to Embodiment 1 until it outputs multiple correction charts and stabilization charts to the printer 140. Hereinafter, the specified number of outputs will be assumed to be 2, and the image processing device 100 will be described as outputting two correction charts 610 and 620, each with a different purpose for automatic gradation correction, to the printer 140.

[0045] First, in S701, the image processing device 100 (CPU 201) acquires information indicating the specified number of outputs. Next, in S703, the image processing device 100 (CPU 201) acquires paper feed information. Next, in S703, when the user instructs the start of automatic gradation correction via input operation, the image processing device 100 (CPU 201) acquires instruction information indicating the start of printing of multiple charts, including the stabilization chart. Next, in S704, the print control unit 101 controls the printer 140 to print two first stabilization charts 611. Next, in S705, the print control unit 101 controls the printer 140 to print the first correction chart 610. Next, in S706, the print control unit 101 controls the printer 140 to print two second stabilization charts 621. Next, in S707, the print control unit 101 controls the printer 140 to print the second correction chart 620. In Figure 7, the processing flow is shown divided into S704 to S707 as an example, but for example, the print jobs for processing from S704 to S707 may be output continuously as a single print job.

[0046] After S707, the print control unit 101 completes the processing of the flowchart shown in Figure 7 and waits until it receives instruction information to start reading each chart output by the printer 140. After S707, the image processing device 100 may display a GUI screen indicating that all charts have been output, prompting the user to place all output charts in the document tray 400, or prompting the user to scan each output chart one by one. After all charts have been output from the printer 140, the user places all output charts in the document tray 400, maintaining their order. After placing all charts in the document tray 400, the user performs an input operation to instruct the start of reading on a GUI screen not shown in Figure 5.

[0047] Figure 8 is a flowchart illustrating an example of the processing flow in the image processing device 100 according to Embodiment 1, from reading multiple correction charts and stabilization charts to generating (updating) a conversion table. First, in S801, the image processing device 100 (CPU 201) acquires instruction information indicating the start of reading the original document (chart). Next, in S802, the image processing device 100 (CPU 201) determines whether or not there is an original document (chart) in the document tray 400 based on information indicating the detection result by the document sensor 402. If it is determined in S802 that there is an original document (chart), in S803, the acquisition unit 102 controls the reading of the original document and acquires scanned image data corresponding to the read chart. After S803, the image processing device 100 returns to S802 and repeatedly executes the processes of S802 and S803 until it is determined in S802 that there is no original document (chart).

[0048] If it is determined in S802 that there is no original document (chart), then in S804, the generation unit 102 identifies the scan image data corresponding to the correction chart from among the multiple scan image data acquired in S803. After S804, in S805, the generation unit 102 determines whether all correction charts output from the printer 140 have been scanned using the flowchart shown in Figure 7. If it is determined in S805 that at least one of the correction charts has not been scanned, then in S806, the image processing device 100 (CPU 201) controls the display unit 205 to display an error GUI screen (error screen) indicating the error. If it is determined in S805 that all correction charts have been scanned, then in S807, the generation unit 102 generates (updates) a conversion table. After S807, the image processing device 100 may display a GUI screen indicating that automatic gradation correction is complete. After S806 or S807, the image processing device 100 terminates the flowchart shown in Figure 8.

[0049] In S802, it is determined whether or not there is a chart in the document tray 400 based on the information indicating the detection result by the document sensor 402, but the processing in S802 is not limited to this. For example, if the image forming apparatus 1 does not have an ADF unit, or if the user performs an input operation to select not to use the ADF unit, it may be determined whether or not an input operation indicating the completion of scanning has been performed by the user. Also, for example, in this case, it may be determined whether or not an input operation indicating the start of a new scan has been performed by the user for a predetermined period of time. Furthermore, if it is determined in S805 that at least one of all the correction charts has not been scanned, only the conversion table corresponding to the identified correction chart may be generated (updated) using the scanned image data corresponding to that correction chart. Furthermore, after processing in S806, the image processing apparatus 100 may return to processing in S801 and display a GUI screen prompting the user to start reading all or additional charts.

[0050] With the image processing device 100 configured as described above, when printing multiple correction charts and stabilization charts and performing automatic gradation correction using multiple correction charts from among the printed charts, the effort required of the user can be reduced.

[0051] In Embodiment 1, it was described that a correction chart image used for automatic tone correction corresponding to one image processing step is printed on a single recording medium, but the invention is not limited to this. For example, at least one of the first correction chart 610 and the second correction chart 620 may have two or more correction chart images used for automatic tone correction corresponding to two or more image processing steps, such as screen screen processing and halftone screen processing. In this case, the generation unit 103 generates (updates) a conversion table corresponding to each of the two or more correction chart images using the scanned image data corresponding to the correction chart on which the two or more correction chart images are printed.

[0052] <Embodiment 2> Referring to Figures 9 and 10, the image processing apparatus 100 according to Embodiment 2 will be described. The image processing apparatus 100 according to Embodiment 2 includes a print control unit 101, an acquisition unit 102, and a generation unit 103, similar to the image processing apparatus 100 according to Embodiment 1. Furthermore, the image processing apparatus 100 according to Embodiment 2 is applied to, for example, an image forming apparatus 1, similar to the image processing apparatus 100 according to Embodiment 1. In addition, the processing of each part of the image processing apparatus 100 according to Embodiment 2 is performed by hardware such as an ASIC or FPGA, or by software using memory such as RAM and a processor such as a CPU, similar to the image processing apparatus 100 according to Embodiment 1.

[0053] The image processing device 100 according to Embodiment 1 identified scanned image data corresponding to the correction chart based on a specified number of outputs. In contrast, the image processing device 100 according to Embodiment 2 identifies scanned image data corresponding to the correction chart based on an identification image captured in the scanned image. For example, when placing a chart bundle consisting of multiple charts output from the printer 140 into the document tray 400, there is no guarantee that the bundle will be placed in the document tray 400 in the same order as it was output due to events such as the user accidentally dropping part or all of the bundle. If the order of the charts in the chart bundle is changed, the image processing device 100 according to Embodiment 1 may mistakenly identify the first correction chart 610 and the second correction chart 620 as each other. There is also a possibility that the stabilization charts 611 and 621 may be mistakenly identified as the first correction chart 610 or the second correction chart 620. As a result, it may not be possible to generate the correct conversion table that should be generated, or to update to the correct conversion table that should be generated.

[0054] The image processing device 100 according to Embodiment 2 (hereinafter simply referred to as "image processing device 100") makes it possible to accurately identify the first correction chart 610 and the second correction chart 620 even when the order of the charts in the chart bundle is changed.

[0055] Figure 9 shows examples of correction charts 910, 920, and stabilization chart 900 output from the printer 140 when automatic gradation correction is performed in the image processing device 100 according to Embodiment 2. Specifically, Figure 9(a) shows an example of the stabilization chart 900 output from the printer 140 when automatic gradation correction is performed according to Embodiment 2. Figure 9(b) shows an example of the first correction chart 910 output from the printer 140 when automatic gradation correction is performed according to Embodiment 2, and Figure 9(c) similarly shows an example of the second correction chart 920.

[0056] When the print control unit 101 is instructed to start automatic gradation correction, it controls the printer 140 to print the correction charts 910, 920 and the stabilization chart 900 in a predetermined order. Here, when printing the correction charts 910 and 920, the print control unit 101 controls the printer to print identification images that allow the correction charts 910 and 920 to be distinguished from each other.

[0057] For example, the print control unit 101 first controls the printer 140 to print a stabilization chart image in order to ensure stable printing of the first correction chart image, and outputs two stabilization charts 900 from the printer 140. Next, it controls the printer 140 to print the first correction chart image, and outputs the first correction chart 910 from the printer 140. At this time, the print control unit 101 controls the printer so that, in addition to the first correction chart image, an identification image 911 for identifying the first correction chart 910 is printed on the first correction chart 910. Next, the print control unit 101 controls the printer 140 to print a stabilization chart image in order to ensure stable printing of the second correction chart image, and outputs two stabilization charts 900 from the printer 140. Next, it controls the printer 140 to print the second correction chart image, and outputs the second correction chart 920 from the printer 140. At this time, the print control unit 101 controls the printing so that, in addition to the second correction chart image, an identification image 921 for identifying the second correction chart 920 is printed on the first correction chart 920.

[0058] Here, identification image 911 and identification image 921 are images that can distinguish the first correction chart 910 and the second correction chart 920, respectively. Specifically, for example, identification image 911 and identification image 921 are images composed of different colors. For example, identification image 911 is an image composed of cyan, and identification image 921 is an image composed of magenta. The aforementioned different colors are not limited to single colors such as cyan or magenta, but may be a combination of multiple different colors, or expressed by a single color gradation, etc. Also, identification image 911 and identification image 921 may be images that consist of different shapes. For example, identification image 911 is an image showing a triangle, and identification image 921 is an image showing a square. Also, for example, identification image 911 and identification image 921 may be images composed of different one-dimensional codes such as barcodes or two-dimensional codes such as QR codes (registered trademarks) of different shapes. Furthermore, identification image 911 and identification image 921 may be printed in different positions on the correction chart.

[0059] Furthermore, the stabilization chart 900 shown in Figure 9(a) does not have identification images printed on it that correspond to the identification images 911 and 921 shown in Figure 9(b) or Figure 9(c). However, this is merely an example and is not limited to this. For example, when the print control unit 101 controls the printing of the stabilization chart 900, it may control the printing so that, in addition to the stabilization chart image, an identification image not shown in Figure 9(a) for identifying the stabilization chart 900 is printed on the stabilization chart 900.

[0060] Figure 10 shows an example of the overlapping of chart bundles when the correction charts 910, 920 and stabilization chart 900, output from the printer 140 by print control of the image processing device 100 according to Embodiment 2, are placed on the document tray 400. Figure 10(a) shows an example of when the bundles of charts output from the printer 140 are placed on the document tray 400 while maintaining their order. The acquisition unit 102 controls the ADF unit to transport all the charts one by one to the pickup roller 404, starting with the chart closest to the front in Figure 10(a) (the first stabilization chart 900). At this time, the acquisition unit 102 controls the scanner 130 simultaneously with the ADF unit to scan each chart with the CIS 408. The acquisition unit 102 acquires scanned image data corresponding to each chart obtained by scanning.

[0061] First, the generation unit 103 identifies scan image data corresponding to each of the multiple correction charts from the scan image data acquired by the acquisition unit 102, based on the identification image captured in each scan image. Next, the generation unit 103 generates (updates) a conversion table using the identified scan image data (scan image data corresponding to each of the multiple correction charts). Specifically, for example, the generation unit 103 determines which of cyan, magenta, and background color (e.g., white) pixels are more numerous in the scan image data acquired by the acquisition unit 102, from among the pixels included in a predetermined image area. As a result of the determination, for example, if there are many pixels close to cyan in a certain scan image data, the generation unit 103 identifies that scan image data corresponds to the first correction chart 910. Also, as a result of the determination, for example, if there are many pixels close to magenta in a certain scan image data, the generation unit 103 identifies that scan image data corresponds to the second correction chart 920. Furthermore, the generation unit 103 may identify a scan image data as corresponding to the stabilization chart 900 if it contains many pixels that are close to the background color.

[0062] When the order of the charts in the bundle of charts is as shown in Figure 10(a) as an example, the generation unit 103 identifies the correction charts 910 and 920 as follows. Specifically, in this case, the generation unit 103 identifies the scan image data corresponding to the first, second, fourth, and fifth charts as scan image data corresponding to the stabilization chart 900 because no identification image is printed on them. Also, for the scan image data corresponding to the third chart, the identification image 911 associated with the first correction chart image is detected, so it is identified as scan image data corresponding to the first correction chart 910. Similarly, for the scan image data corresponding to the sixth chart, the identification image 921 associated with the second correction chart image is detected, so it is identified as scan image data corresponding to the second correction chart 920.

[0063] Figure 10(b) shows an example of a case where the order of charts in a chart bundle is reversed when the bundle of charts output from the printer 140 is placed in the document tray 400. When the order of charts in the chart bundle placed in the document tray 400 is as shown in Figure 10(b), the generation unit 103 identifies the correction charts 910 and 920 as follows. Specifically, in this case, the generation unit 103 identifies the scanned image data corresponding to the first to fourth charts as the scanned image data corresponding to the stabilization chart 900 because no identification image is printed on it. Also, for the scanned image data corresponding to the fifth chart, the identification image 921 associated with the second correction chart image is detected, so it is identified as the scanned image data corresponding to the second correction chart 920. Similarly, for the scanned image data corresponding to the sixth chart, the identification image 911 associated with the first correction chart image is detected, so it is identified as the scanned image data corresponding to the first correction chart 910.

[0064] The processing flow in the image processing device 100 according to Embodiment 2 is the same as the processing flow shown as an example in the flowchart in Figures 7 and 8, so a detailed explanation is omitted. In addition, in the processing of S705 and S706 shown in Figure 7, the image processing device 100 according to Embodiment 2 controls the printing of a correction chart including a correction chart image and an identification image corresponding to the correction chart image. Furthermore, in the processing of S804 shown in Figure 8, the image processing device 100 according to Embodiment 2 identifies a correction chart based on the identification image.

[0065] With the image processing device 100 configured as described above, when printing multiple correction charts and stabilization charts and performing automatic gradation correction using multiple correction charts from among the printed charts, the effort required of the user can be reduced. Furthermore, with the image processing device 100, even if the order of the multiple charts scanned by the scanner 130 differs from the order of the multiple charts output from the printer 140, the correct conversion table to be generated can be produced.

[0066] <Other Embodiments> This disclosure can also be implemented by supplying a program that implements one or more of the functions of the embodiments described above to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be implemented by a circuit (e.g., an ASIC) that implements one or more functions.

[0067] Within the scope of this disclosure, it is possible to freely combine the embodiments, modify any component of each embodiment, or omit any component in each embodiment. [Explanation of symbols]

[0068] 100 Image Processing Devices 101 Printing Control Unit 102 Acquisition Department 103 Generation part

Claims

1. A printing means for printing an image, A transport means for transporting printed materials printed by the aforementioned printing means, A reading means for reading the printed material transported by the transport means, A correction means for performing gradation correction, It has, The printing means prints a first predetermined image on a first sheet without printing the first identification image, then prints the first identification image and the first gradation correction chart on a second sheet, then prints the second predetermined image on a third sheet without printing the second identification image, then prints the second identification image and the second gradation correction chart on a fourth sheet, The reading means reads the first sheet, the second sheet, the third sheet, and the fourth sheet that have been transported by the transport means. The correction means performs a first tone correction based on a first read identification image corresponding to the first identification image and a first read tone correction chart corresponding to the first tone correction chart, obtained by reading by the reading means, and performs a second tone correction based on a second read identification image corresponding to the second identification image and a second read tone correction chart corresponding to the second tone correction chart, obtained by reading by the reading means. An image processing device characterized by the following.

2. The correction means identifies the first reading gradation correction chart based on the first reading identification image, and identifies the second reading gradation correction chart based on the second reading identification image. The image processing apparatus according to claim 1, characterized in that

3. The first identification image and the second identification image are different images from each other. An image processing apparatus according to claim 1 or 2, characterized by the above.

4. The position of the first identification image printed on the second sheet and the position of the second identification image printed on the fourth sheet are different from each other. An image processing apparatus according to claim 1 or 2, characterized by the above.

5. A printing means for printing an image, A transport means for transporting printed materials printed by the aforementioned printing means, A reading means for reading the printed material transported by the transport means, A correction means for performing gradation correction, It has, The printing means prints a first predetermined image on a first sheet, then prints a first tone correction chart on a second sheet, after printing the second sheet, then prints a second predetermined image on a third sheet, and after printing the third sheet, then prints a second tone correction chart on a fourth sheet. The reading means reads the first sheet, the second sheet, the third sheet, and the fourth sheet that have been transported by the transport means. The correction means performs a first tone correction based on a first read tone correction chart corresponding to the first tone correction chart, which is obtained by reading a sheet identified based on the number of printed sheets from among the sheets read by the reading means, and performs a second tone correction based on a second read tone correction chart corresponding to the second tone correction chart, which is obtained by reading a sheet identified based on the number of printed sheets from among the sheets read by the reading means. An image processing device characterized by the following.

6. The number of prints is specified based on user input. The image processing apparatus according to claim 5, characterized by the following:

7. The number of printed sheets is equal to or greater than the number necessary to stabilize the printing of the first tone correction chart and the second tone correction chart, respectively. The image processing apparatus according to claim 5 or 6, characterized by the above.

8. The correction means generates a first conversion table based on the first reading gradation correction chart, performs the first gradation correction using the generated first conversion table, generates a second conversion table based on the second reading gradation correction chart, and performs the second gradation correction using the generated second conversion table. An image processing apparatus according to any one of claims 1 to 7, characterized by the following:

9. The first predetermined image is a stabilization chart for stabilizing the printing of the first gradation correction chart, The second predetermined image is a stabilization chart for stabilizing the printing of the second tone correction chart. An image processing apparatus according to any one of claims 1 to 8, characterized by the following:

10. The correction means generates a conversion table used for gradation conversion when generating a halftone pattern by performing error diffusion processing based on the first gradation correction chart, and performs the first gradation correction using the generated conversion table. An image processing apparatus according to any one of claims 1 to 9, characterized by the above.

11. The correction means generates a conversion table used for gradation conversion when generating a halftone pattern by performing screen processing based on the second gradation correction chart, and performs the second gradation correction using the generated conversion table. An image processing apparatus according to any one of claims 1 to 10, characterized by the above.

12. A printing step of printing an image, A transport process for transporting the printed material printed by the aforementioned printing process, A reading step which reads the printed material that has been transported by the transport step, The correction process involves performing gradation correction, Includes, The printing process involves printing a first predetermined image on a first sheet without printing the first identification image, then printing the first identification image and the first gradation correction chart on a second sheet, printing the second sheet, then printing the second predetermined image on a third sheet without printing the second identification image, and then printing the third sheet, then printing the second identification image and the second gradation correction chart on a fourth sheet. The reading step reads the first sheet, the second sheet, the third sheet, and the fourth sheet that were transported by the transport step. The correction step performs a first tone correction based on a first read identification image corresponding to the first identification image and a first read tone correction chart corresponding to the first tone correction chart, obtained by reading in the reading step, and performs a second tone correction based on a second read identification image corresponding to the second identification image and a second read tone correction chart corresponding to the second tone correction chart, obtained by reading in the reading step. An image processing method characterized by the following.

13. A printing step of printing an image, A transport process for transporting the printed material printed by the aforementioned printing process, A reading step which reads the printed material that has been transported by the transport step, The correction process involves performing gradation correction, Includes, The printing process, based on the number of copies specified by the user, involves printing a first predetermined image on a first sheet, then printing a first tone correction chart on a second sheet, printing a second predetermined image on a third sheet, printing a second tone correction chart on a fourth sheet, and so on. The reading step reads the first sheet, the second sheet, the third sheet, and the fourth sheet that were transported by the transport step. The correction step involves performing a first tone correction based on a first read tone correction chart corresponding to the first tone correction chart, which is obtained by reading a sheet identified based on the number of printed sheets from among the sheets read in the reading step, and performing a second tone correction based on a second read tone correction chart corresponding to the second tone correction chart, which is obtained by reading a sheet identified based on the number of printed sheets from among the sheets read in the reading step. An image processing method characterized by the following.

14. A program for operating a computer as an image processing device according to any one of claims 1 to 11.

Images