Image processing device, image processing method, and program

Abstract

To provide a color adjustment technology that uses a sample document when there is one and appropriately determines a target color even without the sample document.SOLUTION: An image processing apparatus adjusts conversion characteristics in color matching processing in outputting image data in an image output device, and comprises: first setting means 301 that sets, of colors included in the image data, a color selected by a user to a color to be adjusted; second setting means 303 that sets, of colors included in scan image data obtained by reading a sample to be a reference, a color selected by the user to a target color for the color to be adjusted; and changing means that changes the conversion characteristics in the color matching processing based on the target color. The second setting means has a function to set the target color based on first scan image data of a color sample on which patches in a plurality of colors including a peripheral color of the color to be adjusted are printed, and a function to set the target color based on second scan image data of a sample document of the image data to be output.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a color adjustment technique for performing output processing such as printing based on image data. [Background technology]

[0002] When performing a printing process based on image data, for example, the colors in the image data to be printed are adjusted. Color adjustment in this case is generally performed as follows. First, the user selects the color to be adjusted from the image data to be printed (hereinafter referred to as the "color to be adjusted"). Next, multiple candidates for the target color of the color to be adjusted (hereinafter referred to as the "target color") are calculated and printed, and the user is allowed to select the target color from among them. Then, a color conversion LUT is generated such that, when a color signal value indicating the color to be adjusted is input, a color signal value corresponding to the target color is output.

[0003] Regarding color adjustment as described above, Patent Document 1 describes a technique for outputting samples of a color patch of one target color candidate combined with color patches of colors surrounding the target color candidate, and allowing the user to select a target color from the sample. Patent Document 2 describes a technique for optically reading a sample printout, and allowing the user to specify a portion of the read image (scanned image) that will become the target color, thereby setting the target color. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-166305 A [Patent Document 2] JP 2011-205505 A Summary of the Invention [Problem to be solved by the invention]

[0005] When a user has a sample printed matter containing the target color at hand, it is convenient for the user to select the target color using the printed matter. Even in such a case, the technology of Patent Document 1 requires the user to select the target color by comparing the result of the sample output consisting of a plurality of color patches with the printed matter containing the target color, which is troublesome for the user. Moreover, the technology of Patent Document 2 presupposes that the user has a sample printed matter containing the target color at hand, and the target color cannot be set without the sample printed matter. [Means for solving the problem]

[0006] The image processing device according to the present disclosure is an image processing device that adjusts conversion characteristics in a color matching process when image data is output by an image output device, and is equipped with a first setting means that sets a color selected by a user from among the colors contained in the image data to be output as a color to be adjusted, a second setting means that sets a color selected by the user from among the colors contained in scanned image data obtained by reading a reference sample as a target color for the color to be adjusted, and a change means that changes the conversion characteristics in the color matching process when a color signal corresponding to the color to be adjusted is input based on the target color, and is characterized in that the second setting means has a function of setting the target color based on first scanned image data obtained by reading as the sample a color sample on which patches of multiple colors including peripheral colors of the color to be adjusted are printed, and a function of setting the target color based on second scanned image data obtained by reading as the sample a sample original of the image data to be output. Effect of the Invention

[0007] According to the technology disclosed herein, if a sample printed matter is available, it can be used to set a target color, and even if a sample printed matter is not available, the target color can be set based on the color sample. [Brief description of the drawings]

[0008] [Figure 1] Block diagram showing the hardware configuration of the MFP [Diagram 2] Functional block diagram showing the internal configuration of the image processing unit [Diagram 3] FIG. 1 is a functional block diagram showing an internal configuration of a spot color adjustment unit according to a first embodiment; [Figure 4] A diagram showing an example of a UI screen for adjusting spot colors [Diagram 5] A flowchart showing the process of setting a specific color (adjustment target color) that is the target of spot color adjustment. [Figure 6] (a) is a diagram showing the UI screen state for obtaining a color sample, and (b) is a diagram showing a color sample obtained by printing a patch image. [Figure 7] 1 is a flowchart showing a process for generating a patch image. [Figure 8] A diagram showing a message window prompting the user to read a sample [Figure 9] A flowchart showing the flow of a process for setting a target color for a color to be adjusted. [Figure 10] FIG. 1A is a diagram showing a state of the UI screen when a sample manuscript is scanned, and FIG. 1B is a diagram showing an example of the UI screen when a color sample is scanned. [Figure 11] FIG. 11 is a functional block diagram showing the internal configuration of a spot color adjustment unit according to a second embodiment. [Figure 12] FIG. 1A is a diagram showing the UI screen when starting to set the color to be adjusted, and FIG. 1B is a diagram showing the UI screen after the setting is completed. [Figure 13] Flowchart showing the flow of automatic generation of color samples [Figure 14] FIG. 1A is a diagram showing a UI screen when the setting of the target color based on the sample manuscript is completed, and FIG. 1B is a diagram showing a UI screen when the setting of the target color for all colors to be adjusted is completed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment does not limit the present invention, and not all of the combinations of features described in the embodiment are necessarily essential. Note that the same components will be described with the same reference numerals.

[0010] [Embodiment 1] In this embodiment, a specific adjustment target color and its target color are set from the image data to be printed, and color adjustment is performed so that the output signal value corresponding to the signal value (input signal value) of the adjustment target color becomes the output signal value corresponding to the target color. First, let us confirm the background for which such color adjustment is required.

[0011] In recent years, with the improvement of the performance of home and office printers, printers capable of achieving the same image quality as commercial printers have appeared. As a result, the so-called POP printing used in retail stores has become easier to do in each store. Here, POP is an abbreviation for Point of purchase advertising, which refers to advertising for sales promotion. In such cases, due to differences in the model of the printer used, the printed material may be printed in a different color from the sample printed material. In such cases, color adjustments are made to ensure that the printed material can be printed in the same color as the sample printed material.

[0012] In this embodiment, a so-called MFP (Multi Function Printer) will be described as an example of an image forming apparatus that forms an image on a recording medium by electrophotography according to image data to be printed. However, the scope of application of the technology disclosed herein is not limited to MFPs, and is broadly applicable to image output devices in general that output images according to input image data. In other words, the technology is applicable to image display devices such as monitors and projectors in addition to other types of image forming devices such as copiers, laser printers, and inkjet printers.

[0013] <Hardware configuration of image forming device> 1 is a block diagram showing the hardware configuration of an MFP according to this embodiment. The MFP 100 includes a CPU 101, a ROM 102, a RAM 103, a mass storage device 104, a UI unit 105, an image processing unit 106, an engine interface (I / F) 107, a network I / F 108, and a scanner I / F 109. These units are connected to each other via a system bus 110. The MFP 100 also includes a printer engine 111 and a scanner unit 112. The printer engine 111 and the scanner unit 112 are connected to the system bus 110 via the engine I / F 107 and the scanner I / F 109, respectively. The image processing unit 106 may be configured as an image processing device (image processing controller) independent of the MFP 100.

[0014] The CPU 101 controls the overall operation of the MFP 100. The CPU 101 executes various processes described below by reading out a program stored in the ROM 102 into the RAM 103 and executing it. The ROM 102 is a read-only memory, and stores a system startup program or a program for controlling a printer engine, character data or character code information, and the like. The RAM 103 is a volatile random access memory, and is used as a work area for the CPU 101 and a temporary storage area for various data. For example, the RAM 103 is used as a storage area for storing font data additionally registered by downloading, or image files received from an external device, and the like. The mass storage device 104 is, for example, an HDD or SSD, and is used to spool various data and store programs, look-up tables (LUTs), information files, image data, and the like, and as a work area.

[0015] The UI (user interface) unit 105 is composed of, for example, a liquid crystal display (LCD) with a touch panel function, and displays the setting state of the MFP 100, the status of processing in progress, error states, etc. For example, it is also used to display candidates for adjustment target colors and candidates for target colors when performing color adjustment processing. The UI unit 105 also accepts various user instructions such as input of values ​​for various settings of the MFP 100 and selection of various buttons. For example, settings and execution instructions related to color adjustment processing are also made via the UI unit 105. The UI unit 105 may also be provided with a separate input device such as a hard key.

[0016] The engine I / F 107 functions as an interface for controlling the printer engine 111 in response to an instruction from the CPU 101 when printing is performed. An engine control command and the like are transmitted and received between the CPU 101 and the printer engine 111 via the engine I / F 107. The network I / F 108 functions as an interface for connecting the MFP 100 to a network 113. The network 108 may be, for example, a LAN or a telephone line network (PSTN). The printer engine 111 forms a multi-color image on a recording medium such as paper using color materials (here, toner) of multiple colors (here, four colors of CMYK) based on the print image data received from the system bus 110 side. The scanner I / F 109 functions as an interface for controlling the scanner unit 112 in response to an instruction from the CPU 101 when the scanner unit 112 reads an original. A scanner unit control command and the like are transmitted and received between the CPU 101 and the scanner unit 112 via the scanner I / F 109. Under the control of the CPU 101 , the scanner unit 112 optically reads an original document, generates read image data, and transmits the read image data (scanned image data) to the RAM 103 or the mass storage device 104 via the scanner I / F 109 .

[0017] In this embodiment, it is assumed that, for example, when the printer engine 111 prints using input image data for POP printing, the resulting printout has a different color from the sample printout. Then, the user who recognizes that the color in the printout is different from the sample printout operates the UI unit 105 and inputs an instruction to perform color adjustment for the color that is different and that the user wants to adjust (i.e., the color to be adjusted). Then, based on this explicit instruction to perform color adjustment, the color matching LUT that specifies the conversion characteristics in the color matching process is modified to obtain a color matching LUT with new conversion characteristics that can realize the color the user is aiming for for the color to be adjusted. That is, the generation of a new color matching LUT is performed only when an explicit instruction is input from the user. Then, during normal printing processing, the image processing unit 106 does not generate a new color matching LUT each time, but performs color matching processing using a default color matching LUT. In the following description, the adjustment of a specific color based on the above-mentioned explicit instruction by the user is referred to as "spot color adjustment". Also, the sample printout is referred to as "sample manuscript".

[0018] <Configuration of image processing device> 2 is a functional block diagram showing the internal configuration of the image processing unit 106. The image processing unit 106 includes an image input unit 201, a control command generation unit 202, a spot color adjustment unit 203, a color conversion unit 204, a RIP unit 205, a halftone processing unit 206, and an image output unit 207. Each of these functional units is realized by the CPU 101 reading a program stored in the ROM 102 into the RAM 103 and executing it. Alternatively, some or all of these units may be realized by hardware such as an ASIC or an electronic circuit.

[0019] The image input unit 201 accepts input of image data to be printed. The image data is input, for example, from the host PC 115 via the network 113 and the network I / F 108. Alternatively, image data stored in the mass storage device 104 may be input. The input image data is, for example, two-dimensional data composed of planes for each color of red (R), green (G), and blue (B) that expresses a color signal corresponding to the sRGB color space independent of the printer engine 111 in 8 bits (256 gradations). Note that sRGB refers to the standard specification of the RGB color space established by the IEC (International Electrotechnical Commission). The image data input to the image input unit 201 is sent to the control command generation unit 202.

[0020] The control command generation unit 202 controls the spot color adjustment unit 203 and the color conversion unit 204 to obtain image data in the CMYK color space that can be handled by the printer engine 111. Then, a control command for the RIP unit 205 (hereinafter referred to as the "RIP control command") is generated that includes the obtained image data in the CMYK color space. The generated RIP control command is sent to the RIP unit 205.

[0021] The spot color adjustment unit 203 adjusts the color matching LUT used in the color matching process under the control of the control command generation unit 202 based on an execution instruction of the spot color adjustment by the user. The color matching process refers to a process of converting the color space of the image data to be outputted so as to match the color reproducibility of the image outputting device when outputting an image by the image outputting device. In the present embodiment, it means a process of converting the color space of the input image data to be printed received by the image input unit 201 from sRGB, which is independent of the printer engine 111, to RGB, which is dependent on the printer engine 111. Hereinafter, the so-called device-dependent RGB color space, which is dependent on the color reproducibility of the printer engine 111, will be referred to as "devRGB". The color matching LUT holds input values ​​and output values ​​at multiple discrete points (corresponding to lattice points described later) in the color space in association with each other. The spot color adjustment unit 203 corrects the conversion characteristics of the color matching LUT prepared in advance so that a color signal identical to the target color is outputted when a color signal corresponding to the color to be adjusted is inputted. Here, the color to be adjusted is a first color, the color output when the first color is input to a default color matching LUT is a second color, and the color corresponding to the target color is a third color. Correcting the conversion characteristics means replacing the color output when the first color is input with the third color instead of the second color. In other words, a new color matching LUT is generated that outputs the third color when the color to be adjusted is input as the first color. Details of the processing in the spot color adjustment unit 203 will be described later.

[0022] The color conversion unit 204 converts the pixel value of each pixel of the input image data from a value expressed in the sRGB color space (sRGB value) to a value expressed in the CMYK color space (CMYK value) using the above-mentioned color matching LUT and color conversion LUT. The color matching LUT and color conversion LUT are stored in the RAM 103 or the mass storage device 104. First, the color conversion unit 204 performs a color matching process to convert the pixel value of the input image data from an sRGB value to a devRGB value using the color matching LUT. At this time, by using the color matching LUT newly generated by the above-mentioned spot color adjustment, the adjustment target color included in the input image data approaches the target color, which is the color to be aimed for. Furthermore, the color conversion unit 204 performs a color conversion process on the image data after the color matching process using two color conversion LUTs, a first color conversion LUT that converts from the devRGB color space to the Lab color space, and a second color conversion LUT that converts from the Lab color space to the CMYK color space. As a result, image data in which each pixel is expressed in CMYK values ​​is obtained. Note that "Lab" is an abbreviation of "L*a*b*", which is a three-dimensional visually uniform color space that is independent of the printer engine 111 and takes into account human visual characteristics, as defined by the CIE (International Commission on Illumination). By converting colors via a standard color space that is independent of the printer engine 111, reproduction of colors that humans recognize as the same color is realized. Note that the processing in the color conversion unit 204 is not limited to the above. For example, a single LUT may be created by combining the color matching LUT and two color conversion LUTs, and conversion from the sRGB color space to the CMYK color space may be performed all at once. Also, a configuration may be used in which color matching processing and color conversion processing are performed on image data based on a functional formula instead of an LUT.

[0023] A RIP (Raster Image Processor) unit 205 uses the RIP unit control commands generated by the control command generating unit 202 to generate raster format image data expressed in the CMYK color space (hereinafter, referred to as “CMYK raster image data”).

[0024] The halftone processing unit 206 performs halftone processing on the CMYK raster image data generated by the RIP unit 205 to generate print image data (halftone image data) expressed by halftone dots that can be processed by the printer engine 111. The printer engine 111 is often capable of outputting a lower number of gradations than the number of gradations of the input image data, such as two gradations, four gradations, or sixteen gradations. For this reason, halftone processing is performed so that stable halftone expression is possible even when printing and outputting with a small number of gradations as described above. Note that halftone processing methods include a density pattern method, an ordered dither method, an error diffusion method, and the like, and these well-known methods can be applied.

[0025] When the image output unit 207 receives the print image data from the halftone processing unit 206, it transmits the print image data to the printer engine 111 via the engine I / F 107. The CPU 101 instructs the printer engine 111 to form an image based on the print image data. The printer engine 111 executes each process of exposure, development, transfer, and fixing to form and output a color image on a recording medium according to the input print image data.

[0026] (Details of spot color adjustment section) 3 is a functional block diagram showing the internal configuration of the spot color adjustment unit 203 according to this embodiment. The spot color adjustment unit 203 has an adjustment target color setting unit 301, a color sample generation unit 302, a target color setting unit 303, a color reproduction range acquisition unit 304, an output color determination unit 305, and an LUT modification unit 306. Each of these functional units is realized by the CPU 101 reading a program stored in the ROM 102 into the RAM 103 and executing it. Alternatively, some or all of these may be realized by hardware such as an ASIC or an electronic circuit. Each functional unit will be described below.

[0027] The adjustment target color setting unit 301 performs a process of setting a specific color (adjustment target color) that is a target of spot color adjustment among colors that constitute an input image to be printed. This will be described in detail with reference to FIG. 4 and FIG. 5. In this specification, the symbol "S" in the description of a flowchart means a step. First, the adjustment target color setting unit 301 receives input image data to be printed from the control command generating unit 202 (S501). Then, based on the received input image data, the input image is displayed on a spot color adjustment UI screen displayed on the UI unit 105 (S502). FIG. 4 shows an example of a spot color adjustment UI screen (hereinafter simply referred to as a "UI screen") according to this embodiment. When setting an adjustment target color, first, as shown in FIG. 4, an input image 402 is displayed in the image display area 401. Then, a user selection for the displayed input image 402, that is, a selection of a specific position, is accepted (S503). This selection is realized, for example, by the user touching the area of ​​"30% off all items" in the input image 402 in the image display area 401, and acquiring coordinate information (x, y) corresponding to the position of the touch operation. Note that instead of the touch operation, a specific position may be selected by a pointing device such as a mouse. Here, x, y represent the horizontal position x (right direction is +) and the vertical position y (down direction is +) on a two-dimensional plane with the top left position of the input image 402 as the origin (0, 0). Next, a color value corresponding to the position related to the user selection is acquired based on the acquired coordinate information (S504). Now, since each pixel of the input image has an sRGB value, the sRGB value at the position selected by the user is acquired. Then, the color corresponding to the acquired sRGB value is displayed in the adjustment target color display area 403 in the UI screen 400 (S505). At this time, the acquired sRGB values ​​(three values ​​of R, G, and B; here, (R=0, G=0, B=160)) are also displayed near the adjustment target color display area 403. Note that the input image displayed in the image display area 401 and the colors displayed in the adjustment target color display area 403 are displayed in an RGB color space dependent on the monitor device, using a monitor color conversion LUT dependent on the monitor device mounted in the UI unit 105.Finally, in response to the user pressing the OK button 404, the color being displayed in the adjustment target color display area 403 is set as the adjustment target color (S506). Then, information on the adjustment target color thus set is sent to the output color determination unit 305.

[0028] The color sample generator 302 generates a patch image consisting of a group of patches corresponding to a plurality of colors that are candidates for the target color, which is the basis of a color sample for determining a target color (target color) of the color to be adjusted. FIG. 6(a) is a diagram showing the state of a UI screen 400 for obtaining a color sample. As shown in FIG. 6(a), the color sample generator 302 first displays a message window 600 on the UI screen 400 to ask the user whether or not a color sample is required. If a color sample is required, that is, if a sample printout containing the target color is not available, the user presses a "Yes" button 601 to instruct printing of a color sample. On the other hand, if a sample manuscript is available and a color sample is not required, the user presses a "No" button 602. In this case, the color sample generator 302 does not operate. Then, the color sample generating unit 302, which detects the pressing of the "Yes" button 601, obtains information on the adjustment target color set based on the user's selection from the adjustment target color setting unit 301, and generates a patch image for obtaining a color sample 603 as shown in FIG. 6(b) based on the information. In the case of the patch image for obtaining the color sample 603 in FIG. 6(b), rectangles (for example, rectangles of 945 pixels x 945 pixels) corresponding to each of the 27 colors including the adjustment target color are arranged in a patch image with a resolution of 600 dpi, 5 horizontally (X direction) and 6 vertically (Y direction). In addition, alphabets A to E are written in the horizontal direction (X direction) at the top of the patch image, and numbers 1 to 6 are written in the vertical direction (Y direction) at the left end. This is to enable the user to specify a desired patch by a patch number (information that can identify each patch) consisting of a combination of alphabets and numbers on a UI screen for setting a target color, which will be described later. The color of each patch at this time is a color defined by sRGB. The total number of patches and the arrangement are arbitrary. Each patch may have a different rectangular size, or may have a different shape than a rectangle. Also, the resolution is not limited to 600 dpi.

[0029] Here, a detailed explanation will be given with reference to the flowchart in Fig. 7. Note that the symbol "S" in the flowchart in Fig. 7 means a step.

[0030] First, the color sample generating unit 302 acquires information on the adjustment target color set by the adjustment target color setting unit 301 (S701). Next, a plurality of colors are calculated by gradually changing the set adjustment target color (S702). The colors calculated here (here, 27 colors including the adjustment target color) become the colors of each patch. In this case, the color is changed, for example, by adding a predetermined change amount to the adjustment target color for each of R, G, and B. Here, the sRGB value indicating the color of the patch when the change amounts are x, y, and z is calculated by the following formulas (1) to (3).

[0031] R out (i) = R in + x(i) + y(i) + z(i)...Equation (1) G out (i) = G in + x(i) + y(i) + z(i)...Equation (2) B out (i) = B in + x(i) + y(i) + z(i)...Equation (3) In the above formulas (1) to (3), “R out ", "G out ", "B out " indicates the R value, G value, and B value after the adjustment target color is changed. in ", "G in ", "B in " respectively indicate the R value, G value, and B value of the color to be adjusted. Also, i indicates the change number, and the amount of change corresponding to the change number is specified by a table such as that shown in Table 1 below. Note that here, the color is changed based on the sRGB color space, but this is not limited to this, and the color may also be changed based on, for example, the Lab color space or the Luv color space.

[0032] [Table 1]

[0033] Finally, a patch image is generated in which rectangular patches corresponding to the colors obtained by varying the adjustment target color are arranged (S703). A color sample is obtained by printing out the patch image thus obtained. After generating the patch image that is the basis of the color sample as described above, the color sample generating unit 302 converts the sRGB values ​​of each patch into devRGB values ​​using a predetermined conversion table (color matching LUT). The following Table 2 is an example of a color matching LUT.

[0034] [Table 2]

[0035] The patch image data after conversion based on the color matching LUT as shown in Table 2 above is sent to the printer engine 111 via the control command generating unit 202 and printed out.

[0036] The target color setting unit 303 sets a target color (target color) for the adjustment target color set by the adjustment target color setting unit 301. This will be described in detail with reference to FIG. 8 and FIG. 9. The symbol "S" in the flowchart in FIG. 9 means a step. First, the target color setting unit 303 displays a message window 800 prompting the user to read a sample on the UI screen 400 as shown in FIG. 8(a) (S901). In this case, if the user has a sample document 801 (FIG. 8(b)) at hand, the user uses it, and if not, the color sample 802 (FIG. 8(c)) based on the patch image generated by the color sample generating unit 302 is used. That is, the user sets either the sample document or the color sample on the document reading table (not shown) of the scanner unit 112 and presses the "OK" button 803 to instruct the scanner unit 112 to execute reading. In response to the pressing of the "OK" button 803, the scanner unit 112 scans the sample document 801 or the color sample 802. The scanned image data obtained by this scan has a resolution of, for example, 600 dpi, and each pixel is expressed in RGB 8 bits. This scanned image data is also converted from devRGB values, which depend on the color reproducibility of the scanner unit 112, to the sRGB color space using a conversion LUT for the scanner. The scanned image data before and after the conversion are stored in the RAM 103. Next, the target color setting unit 303 reads the scanned image data converted to the sRGB color space from the RAM 103 and displays it on the UI unit 105 (902). Figures 10(a) and (b) show the state of the UI screen 400 when the target color is set, where (a) corresponds to the case where a sample document 801 is scanned, and (b) corresponds to the case where a color sample 802 is scanned. In the case of the UI screen 400 shown in Figure 10(a), a scanned image 1001 of the sample document 801 is displayed in the image display area 401. In the case of the UI screen 400 of Fig. 10(b), a scanned image 1001' of the color sample 802 is displayed in the image display area 401. Also, the UI screen 400 of Fig. 10(b) has an input field 1003 for specifying the above-mentioned patch number. Whether or not to display the UI screen 400 including the input field 1003 may be determined based on the characteristics of the scanned image. The processes from S903 onwards are as follows.When a user operation on the scanned image 1001 or 1001' is accepted, processing is assigned according to the operation content (S903, S904). In the case where the displayed scanned image is the scanned image 1001 of the sample document 801, for example, when the user touches the area of ​​"30% off all items" in the scanned image 1001 in the image display area 401, a color value is acquired based on the coordinate information (x, y) corresponding to the position of the touch operation (S905). Since each pixel of the scanned image also has an sRGB value, the sRGB value at the position selected by the user's touch operation is acquired. Then, the color corresponding to the acquired sRGB value is displayed in the target color display area 1002 (S907). At this time, the acquired sRGB value (three values ​​of R, G, and B. Here, (R=0, G=0, B=180)) is also displayed near the target color display area 1002 (lower part in this example). The scanned image displayed in the image display area 401 and the color displayed in the target color display area 1002 are displayed in a monitor device-dependent RGB color space using a monitor color conversion LUT that is dependent on the monitor device (here, a touch panel) mounted on the UI unit 105. Finally, in response to the user pressing the "Determine" button 404, the color displayed in the target color display area 1002 is set as the target color (S908). Then, information on the target color set in this manner is sent to the output color determination unit 305. On the other hand, when the displayed scanned image is the scanned image 1001' of the color sample 802, if a patch number is input via the input field 1003 and the Confirm button is pressed, the sRGB value, which is the color value of the patch at the position corresponding to the patch number, is acquired (S906). Then, the color corresponding to the acquired sRGB value is displayed in the target color display area 1002 (S907). In this case, the acquired sRGB values ​​(three values ​​of R, G, and B; here, (R=0, G=0, B=180)) are also displayed near (at the bottom in this example) the target color display area 1002. Then, in response to the user pressing the "OK" button 404, the color being displayed in the target color display area 1002 is set as the target color (S908). Information on the target color set in this way is then sent to the output color determination unit 305.

[0037] The color reproduction range acquisition unit 304 acquires information on the color reproduction range of the printer engine 111 from the control command generation unit 202. Here, the color reproduction range of the printer engine 111 means the range of colors that the printer engine 111 can express, for example, in the Lab space, which is a standard color space. Here, the color reproduction range information is acquired in an LUT format that specifies the correspondence between RGB values ​​in the devRGB color space that depends on the printer engine 111 and Lab values ​​in the Lab color space, as shown in Table 3 below.

[0038] [Table 3]

[0039] In Table 1 above, the Lab values ​​given as real values ​​are assumed to take values ​​of 0.0 to 100.0 for L, and -127.0 to 128.0 for a and b. The RGB values, which are input values, are values ​​at discrete positions in the devRGB color space. When an RGB value that is not held as an input value is input, the Lab value is calculated by an interpolation operation using surrounding values. Note that the standard color space used to specify the color reproduction range is not limited to the Lab color space, and other color spaces such as the Luv color space defined by the CIE (International Commission on Illumination) may be used. The acquired color reproduction range information is sent to the output color determination unit 305.

[0040] The output color determination unit 305 determines a color to be output when the adjustment target color is input based on the information on the adjustment target color and its target color set as described above, and on the information on the color reproduction range of the printer engine 111. The output color determination unit 305 first determines whether the Lab value corresponding to the set target color is within the color reproduction range of the printer engine 111. If the Lab value of the target color is within the color reproduction range, the output color is determined to be a color specified by the devRGB value corresponding to the Lab value of the target color. On the other hand, if the Lab value of the target color is outside the color reproduction range, the output color is determined to be a color closest to the target color within the color reproduction range (i.e., a color closest to the color desired by the user). At this time, for example, a chart image including a plurality of candidate colors may be generated and displayed on the UI unit 105, and the user may select a color close to the desired color from the chart image. Note that the chart image may be printed out and the user may select a desired color. In this way, the set target color or a color close to it is determined to be the output color. In this embodiment, the determined output color is specified by color signal values ​​having three values ​​of R, G, and B in the devRGB color space. In this way, in a color matching LUT for converting the color space from sRGB to devRGB, when a color to be adjusted having a predetermined sRGB value is input, a devRGB value is determined that outputs a target color desired by the user (or a color close to the target color). Information on the determined output color is sent to the LUT modification unit 306 together with information on the color to be adjusted.

[0041] The LUT modification unit 306 modifies the default color matching LUT based on the received information on the adjustment target color and output color. For example, assume that the adjustment target color information is an sRGB color signal value of (R=0, G=0, B=160) indicating a dark blue, and the output color information is a devRGB color signal value of (R=0, G=0, B=125). In this case, the LUT modification unit 306 modifies the default color matching LUT shown in Table 2 above as shown in Table 4 below.

[0042] [Table 4]

[0043] In the color matching LUT shown in Table 4, it can be seen that the devRGB value of the grid point corresponding to the sRGB value (R=0, G=0, B=160) of the adjustment target color is rewritten from (R=0, G=0, B=115) to (R=0, G=0, B=125). Rewriting the RGB value corresponding to such a grid point is synonymous with changing the conversion characteristics of the color matching LUT. In this way, a new color matching LUT is obtained for realizing a color matching process that brings the adjustment target color closer to the color desired by the user. Note that here, only the devRGB value of one grid point is changed, but more preferably, a smoothing process is performed so that the difference with the devRGB value at the neighboring grid point becomes smooth. The new color matching LUT generated as described above, in which the adjustment target color designated by the user and the output color are associated with each other, is sent to the color conversion unit 204.

[0044] According to this embodiment, if a sample document is available, it can be used to set the target color, eliminating the need to print a color sample every time and set the target color by comparing it with the sample printout. Even if a sample printout is not available, a color sample can be generated and printed to set the target color appropriately.

[0045] [Embodiment 2] When spot color adjustment is performed for multiple colors in an input image, it is very time-consuming for the user to select the adjustment target colors one by one and set the target color by reading a color sample or a sample document with a scanner unit each time. Therefore, a mode in which multiple adjustment target colors are set first, and then target colors are set based on the sample document for adjustment target colors that have a target color in the sample document, and color samples are automatically generated only for adjustment target colors that do not have a target color in the sample document will be described as embodiment 2. Note that a description of the contents common to embodiment 1, such as the basic configuration of the image processing unit 106, will be omitted, and the following will describe the processing contents in the spot color adjustment unit 203, which is the difference.

[0046] <Spot color adjustment section configuration> (Details of spot color adjustment section) 11 is a functional block diagram showing the internal configuration of a spot color adjustment unit 203' according to this embodiment. The spot color adjustment unit 203' of this embodiment is also configured with the same functional blocks as those of the first embodiment. That is, it has an adjustment target color setting unit 301', a color sample generation unit 302', a target color setting unit 303', a color reproduction range acquisition unit 304, an output color determination unit 305, and an LUT correction unit 306. The following description will focus on the adjustment target color setting unit 301', the color sample generation unit 302', and the target color setting unit 303', which operate in a partially different manner from those of the first embodiment.

[0047] The adjustment target color setting unit 301' performs processing to set multiple adjustment target colors that are the target of spot color adjustment among the colors that constitute the input image. FIG. 12(a) is an example of a UI screen for spot color adjustment according to this embodiment, and shows a state at the start of adjustment target color setting. When input image data to be printed is received from the control command generating unit 202, the adjustment target color setting unit 301' displays an input image 402 in an image display area 401 in a UI screen 400' as shown in FIG. 12(a). On the right side of the image display area 401 is a selected color display area 1201 for displaying multiple adjustment target colors selected by the user and their corresponding target colors. The selected color display area 1201 further includes an adjustment target color area 1202 for displaying the adjustment target color selected by the user, and a target color area 1203 for displaying the target color selected by the user. The UI screen 400' in FIG. 12(a) is a UI screen in a situation where the user has not made any selection. Therefore, in both the adjustment target color area 1202 and the target color area 1203, input fields 1202a to 1202c and 1203a to 1203c in a blank state (blank state) are lined up. When setting an adjustment target color, the user first selects an arbitrary input field from among the blank input fields lined up in the adjustment target color area 1202 by touch operation or the like. Next, when the user selects a specific position of the input image 402 by touch operation or the like, a color value (sRGB value) is acquired based on the coordinate information, and a color corresponding to the acquired sRGB value is entered in the input field in the adjustment target color area 1202 that was selected immediately before. In other words, the input field that was blank changes to a state where a color selected by the user is added. In this way, the first adjustment target color is set. If there are a second or third color, the user repeats the same process to set the desired number of adjustment target colors. FIG. 12(b) shows a UI screen 400′ in a state in which three adjustment target colors have been set. As is clear from a comparison with FIG. 12(a), all three input fields 1202a to 1202c arranged in the adjustment target color area 1202 are colored. After completing the setting of all the adjustment target colors in the above manner, the user presses the “Determine” button 404. When the user presses the “Determine” button 404, information on the multiple adjustment target colors set as described above is sent to the output color determination unit 305.A scroll bar 1204 is used to scroll the screen so that the multiple colors to be adjusted can be checked when the multiple colors to be adjusted do not fit on one screen. Also, a "change sample" button 1205 is used to switch the sample document to be scanned when the target colors corresponding to the multiple colors to be adjusted are included in different sample documents.

[0048] The color sample generating unit 302' automatically generates color samples for the adjustment target colors that require color sample generation among the multiple adjustment target colors set by the adjustment target color setting unit 301'. In other words, the color sample generating unit 302' of this embodiment does not operate when the target color is set using a sample manuscript for each of all adjustment target colors set by the adjustment target color setting unit 301'. Here, the adjustment target colors that require color samples among the multiple adjustment target colors are, for example, cases in which the sample manuscript does not contain the target color, such as when the sample manuscript does not properly reproduce some colors. That is, in this embodiment, the user first determines the target color for adjustment target colors that are included in the sample printout among the multiple adjustment target colors that have been set, using the sample manuscript. Then, for adjustment target colors that do not have the target color in the sample manuscript, the automatically generated color sample is used to determine the target color. Details of the automatic generation process of color samples, which is a feature of this embodiment, will be described later with reference to a separate flowchart (FIG. 13).

[0049] The target color setting unit 303' sets a target color for each of the multiple target colors set by the adjustment target color setting unit 301' based on a user operation. First, for the target colors for which the target color is appropriately expressed in the sample document, the target color is set based on the sample document. As a specific operation, the user first sets the sample document in the scanner unit according to the message window as shown in FIG. 8 described above and scans the sample document. As a result, the scanned image of the sample document is displayed in the image display area 401 in the UI screen 400' described above. Next, the user selects any input field from among the blank input fields arranged in the target color area 1203 in the selected color display area 1201 by a touch operation or the like. Next, when the user selects a specific position on the displayed scanned image by a touch operation or the like, a color value (sRGB value) is acquired based on the coordinate information. Then, a color corresponding to the acquired sRGB value is entered into the input field in the target color area 1203 selected immediately before. In other words, the blank input field changes to a state in which the color selected by the user is added. The user performs such an operation for all the adjustment target colors. When the user has finished setting the target colors for the adjustment target colors that exist in the sample document, the user presses the "OK" button 404. Now, assume that three adjustment target colors have been set as shown in FIG. 12(b) above, and target colors have been set for two of the adjustment target colors based on the sample document. FIG. 14(a) shows the UI screen 400' at this time, and among the three input fields 1203a to 1203c arranged in the target color area 1203, the top input field 1203a and the bottom input field 1203c each contain a color. When the "OK" button 404 is pressed in this state, the target color setting unit 303' associates information on the two set target colors with the corresponding adjustment target colors and sends them to the output color determination unit 305. The output color determination unit 305 determines the output color for each of the two set target colors, and sends the results to the color sample generation unit 302'. Then, the color sample generating unit 302' generates a color sample for the remaining adjustment target color for which a target color has not been set.

[0050] For the adjustment target color that does not exist in the sample document, the target color setting unit 303' sets the target color based on the automatically generated color sample. Now, assume that the situation is as shown in FIG. 14(a). In this case, the user selects the blank input field 1203b in the target color area 1203 by touch operation or the like. The target color setting unit 303', upon detecting this operation, displays a message window (see FIG. 8 described above) on the UI screen 400', prompting the user to set the color sample in the scanner unit. Then, when the user sets the color sample and instructs to execute reading, the color sample is read, scan image data is generated, and a scan image of the color sample is displayed in the image display area 401. After that, as in the case of using the sample document, by performing a touch operation or the like on a desired position in the displayed scan image, the color related to the touch operation or the like is entered in the input field 1203b, and the target color is set. FIG. 14(b) shows a UI screen 400' in a state in which a target color has also been set for the remaining color using target color setting based on a color sample, and the target color setting process has been completed for all three colors to be adjusted.

[0051] When it is determined that no target color will be set based on the sample document, the blank input fields in the target color area 1203 may be highlighted by thickening the outer frame or the word "not set" may be superimposed on them. This allows the user to easily recognize that the target color has not been set, even if, for example, the inside of a blank input field is displayed as "white" and the target color of the adjustment target color is close to white.

[0052] (Automatic generation of color samples) Next, the automatic generation process of a color sample by the color sample generator 302' according to this embodiment will be described in detail with reference to the flowchart in Fig. 13. As described above, the flow shown in Fig. 13 is triggered by the user pressing the "OK" button 404 after the process of setting the target color for the adjustment target color that exists in the sample document is completed.

[0053] First, in S1301, information on all colors to be adjusted set by the user is acquired from output color determination unit 305. In the following S1302, it is determined whether or not the preparation processes in S1303 to S1305 have been completed for all colors to be adjusted specified by the information acquired in S1301. If completed, the process proceeds to S1306, and if not completed, the process proceeds to S1303.

[0054] In S1303, if the preparation process is not complete, information on the target color for the adjustment color of interest among all the adjustment target colors is requested from the output color determination unit 305. If the output color determination unit 305 that received the request has already received information on the target color associated with the adjustment target color of interest from the target color setting unit 303', it returns the information to the color sample generation unit 302'. On the other hand, if the information has not been received (i.e., if a target color has not been set for the adjustment target color of interest), it returns, for example, an error signal indicating that to the color sample generation unit 302'.

[0055] In S1304, it is determined whether or not the information on the aim color for the color to be adjusted under consideration has been acquired. If the information on the aim color has been acquired, the process returns to S1302. On the other hand, if the information on the aim color has not been acquired, the process proceeds to S1305.

[0056] In S1305, a plurality of colors obtained by varying the attention target color to be adjusted are calculated in order to generate a color sample for the attention target color to be adjusted. In this case, as in the first embodiment, for example, 27 colors including the adjustment target color are calculated.

[0057] In S1306, when the above-mentioned preparation process is completed for all adjustment target colors, it is determined whether or not the color for a color sample (patch image) has been calculated for any of the adjustment target colors of interest. If there is an adjustment target color for which the color for the color sample has been calculated, the process proceeds to S1307. On the other hand, if there is no adjustment target color for which the color for the color sample has been calculated, the process ends.

[0058] In S1307, a patch image for a color sample is generated similarly to the first embodiment, using the color calculated in S1305 for each adjustment target color. In this case, if the color for the color sample has been calculated for a plurality of adjustment target colors, it is sufficient that the correspondence between each adjustment target color and the calculated color can be known. In other words, it is not necessary to have one page of patch images for each adjustment target color, and a plurality of adjustment target colors may be included in one page. Then, similarly to the first embodiment, data of the patch image converted using the color matching LUT is sent to the printer engine 111 via the control command generation unit 202 and printed out, and a color sample corresponding to one or a plurality of adjustment target colors is obtained. The above is the content of the automatic color sample generation process according to this embodiment.

[0059] According to this embodiment, when there are multiple colors to be adjusted, it is not necessary to repeat the operation of selecting a target color from the scanned image of the sample print for each color. Also, when there is a color to be adjusted for which the target color does not exist in the sample print, a color sample is automatically generated. Therefore, the operational burden on the user can be significantly reduced.

[0060] (Other embodiments) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

Claims

1. An image processing device that adjusts conversion characteristics in a color matching process when image data is output by an image output device, a first setting means for setting a color selected by a user from among colors included in the image data to be output as a color to be adjusted; a second setting means for setting a color selected by a user from among colors included in the scanned image data obtained by reading a reference sample as a target color for the adjustment target color; a change unit that changes, based on the target color, a conversion characteristic in the color matching process when a color signal corresponding to the adjustment target color is input; Equipped with The second setting means is a function of setting the target color based on first scanned image data obtained by reading a color sample on which patches of a plurality of colors including peripheral colors of the adjustment target color are printed as the color sample; and setting the target color based on second scanned image data obtained by reading a sample original of the image data to be output as the sample.

13. An image processing device comprising:

2. a display unit that displays the first scanned image data or the second scanned image data based on a user instruction; the second setting means sets a color selected by a user based on the scanned image data displayed on the display means as the target color.

2. The image processing device according to claim 1,

3. 3. The image processing apparatus according to claim 1, further comprising a generating unit that generates patch image data that is a basis of the color sample used when the target color is set based on the first scanned image data.

4. The generating means includes: obtaining information on the set color to be adjusted from the first setting means; Calculating a plurality of colors obtained by varying the adjustment target color specified by the acquired information; generating the patch image data in which patches corresponding to the calculated multiple colors are arranged; 4. The image processing device according to claim 3.

5. 5. The image processing apparatus according to claim 3, wherein the generating means generates the patch image data based on a user instruction.

6. The image processing device according to claim 3 or 4, characterized in that when a plurality of colors to be adjusted are set by the first setting means, and when the second setting means sets the target color based on the second scanned image data for some of the plurality of colors to be adjusted, the generation means generates the patch image data for the remaining adjustment target colors among the plurality of colors to be adjusted for which the target color has not been set, without being based on user instructions.

7. 7. The image processing device according to claim 1, wherein the modification means modifies a conversion characteristic in a lookup table that associates input signal values ​​and output signal values ​​for the color matching process so that an output signal value corresponding to an input signal value indicating the color to be adjusted becomes an output signal value indicating the target color or a color as close as possible to the target color.

8. The image output device further includes an acquisition unit for acquiring information about a color reproduction range of the image output device, 8. The image processing apparatus according to claim 7, wherein said change means makes the change so that the color falls within a color reproduction range specified by the acquired information.

9. 9. The image processing apparatus according to claim 7, wherein the image output device is an image forming device that forms an image on a recording medium using color materials in accordance with the input image data.

10. A method for controlling an image processing device that adjusts conversion characteristics in a color matching process when outputting image data from an image output device, comprising: a first setting step of setting a color selected by a user from among colors included in the image data to be output as a color to be adjusted; a second setting step of setting a color selected by a user from among colors included in the scanned image data obtained by reading a reference sample as a target color for the adjustment target color; a changing step of changing, based on the target color, a conversion characteristic in the color matching process when a color signal corresponding to the adjustment target color is input; Including, In the second setting step, A step of setting the target color based on first scanned image data obtained by reading a color sample on which patches of a plurality of colors including peripheral colors of the color to be adjusted are printed as the sample, or a step of setting the target color based on second scanned image data obtained by reading a sample original of the image data to be output as the sample, is executed according to a user's selection. A control method comprising:

11. A program for causing a computer to function as the image processing device according to any one of claims 1 to 9.

Images