JP2024085184A - Image processing apparatus, image processing method, and program - Google Patents

Abstract

To reduce a load for simulating characteristics.SOLUTION: An image processing apparatus includes: analysis means which analyzes PDL data with a designated color value of an object in a page; conversion means which converts, on the basis of analysis result obtained by the analysis means, a color value designated with characteristics, out of color values of a first object and a second object overlapping each other in the page, into color synthesis data; first determination means which determines, on the basis of the color synthesis data generated by the conversion means, a synthesized color which is a color in a region where the first object and the second object overlap each other; and generation means which generates bitmap image data that represents the synthesized color and the characteristics with a process color.SELECTED DRAWING: Figure 6

Description

This disclosure relates to an image processing device, an image processing method, and a program.

In the field of commercial printing, large printing presses that perform offset printing, flexographic printing, gravure printing, etc. are well known, and each type of printing press is used depending on the application. In all types of printing presses, a plate is created for each ink, and the plate for each ink is set up on the press to print. In general color printing, four plates are used, each corresponding to one of the four inks called process colors: cyan (C), magenta (M), yellow (Y), and black (K).

When printing on these large printing presses, multiple steps are required from preparing the plate to starting printing, and returning a work process after the printing process has begun reduces productivity. In particular, if corrections that significantly deviate from the adjustable range of colors are required after the plate has been created, the plate will have to be created again, so color proofing must be carried out carefully. For this reason, there is a process called color proofing, in which a color sample is printed on the printing press before the printing process begins, to check the color finish.

In addition, on large printing presses used in commercial printing, it is possible to set additional plates in addition to the four process color plates. For example, on offset printing presses, it is common to add spot color plates. Even in this case, it is necessary to check the finished color using a color proof before the printing process on the press begins.

Patent document 1 describes a method for calculating a composite color of spot colors. Patent document 2 describes a method for simulating a process color by adding the color value of a spot color and the color value of each process color.

JP 2006-173799 A JP 2015-26933 A

In Patent Document 2, in order to add up the color values of the spot colors and the color values of each of the process colors, it is necessary to store the bitmap image data on a hard disk and then read out the bitmap images of the process colors and the spot colors. Therefore, the method in Patent Document 2 generates a load.

In addition, in the method of Patent Document 2, the process of analyzing PDL data and generating intermediate data basically needs to be performed sequentially, so the task of processing the PDL data is generally assigned to one thread. For this reason, if a configuration is adopted in which spot colors are processed using normal color processing, so-called pre-render CMS (color processing performed before rendering processing), it is not possible to speed up the processing due to operational limitations.

An image forming apparatus according to one aspect of the present disclosure is characterized by having an analysis means for analyzing PDL data in which color values of objects within a page are specified, a conversion means for converting color values of a first object and a second object that overlap within the page, one of which is specified as a spot color, into color blending data based on the analysis results obtained by the analysis means, a first determination means for determining a blending color, which is the color of the area where the first object and the second object overlap, based on the color blending data converted by the conversion means, and a generation means for generating bitmap image data in which the blending color and the spot color are expressed as process colors.

The technology disclosed herein can reduce the load when simulating spot colors.

FIG. 2 is a diagram illustrating an example of a hardware configuration of an image processing device. FIG. 1 is a schematic diagram illustrating a configuration of a printing apparatus. FIG. 1 is a diagram illustrating an example of a schematic configuration of a printing system. 11A and 11B are diagrams for explaining a process in an image processing device of a comparative example. FIG. 2 is a diagram illustrating a functional configuration of the image processing device. FIG. 13 is a diagram for explaining an intermediate data generating unit. FIG. 2 is a diagram for explaining functions within an intermediate data generating unit. 13 is a diagram for explaining a loop process in an intermediate data generating unit; FIG. 13A and 13B are diagrams for explaining processing according to the presence or absence of edge intersection; FIG. 11 is a diagram for explaining a spot color synthesis process. FIG. 13 is a diagram illustrating a database for color synthesis. FIG. 11 is a diagram for explaining spot color synthesis processing. FIG. 13 is a diagram for explaining a database for color synthesis.

Below, the embodiments for implementing the present disclosure will be described with reference to the attached drawings. Note that the following embodiments do not limit the present disclosure, and not all of the combinations of features described in the embodiments are necessarily essential to the solutions of the present disclosure. Note that the same components will be described with the same reference numerals.

<Embodiment 1>
[Hardware configuration of image processing device]
1 is a diagram showing an example of the hardware configuration of an image processing device 100 according to this embodiment. The image processing device 100 has a CPU 101, a RAM 102, a ROM 103, a keyboard controller 105, a display controller 106, a disk controller 107, a PRTC 108, and an NC 112. These components are connected to a bus 104 so as to be able to transmit and receive data to and from each other. The image processing device 100 further has a keyboard 109, a display 110, and an external storage 111.

The CPU 101 executes programs such as an OS or general applications loaded from the ROM 103 or external storage 111 to the RAM 102, and realizes the functions of the image processing device 100 described below. The RAM 102 functions as the main memory, work area, etc. of the CPU 101. The number of CPUs 101 is not limited to one. The keyboard controller (KBC) 105 controls key input from the keyboard 109 or a pointing device (not shown). The display controller 106 controls the display on the display 110. The disk controller (DKC) 107 controls access to the external storage 111, such as a hard disk (HD) or non-volatile storage (flash memory) that stores a boot program, various applications, font data, user files, etc.

The PRTC (printer controller) 108 controls the exchange of signals with the printer engine of the printer that forms and outputs an image on a medium. The NC 112 is connected to a network and executes communication control processing with other devices connected to the network.

[Color Printer Configuration]
2 is a diagram showing an example of the schematic configuration of a printing unit in a color printer 2010 (color proofer) having a printer engine capable of communicating with the PRTC 108. The color ink cartridges 2200, 2210, 2220, and 2230 are filled with yellow (Y) color ink, magenta (M) color ink, cyan (C) color ink, and black (K) color ink, respectively. The ink cartridges 2200, 2210, 2220, and 2230 are connected to the pressure pump 2160 by independent pipes for supplying ink. The ink of each color is pumped from the pressure pump 2160 to the print head 2120 at a constant pressure.

The recording paper is supplied from the rear of the color printer 2010 and is fixed in place by a platen 2110 and a front guide roller 2150. The color printer 2010 is operated by pressing keys on a control panel 2180, and a control board 2190 controls all operations of the color printer 2010.

To print using this color printer 2010, a print control command and print data can be sent to the control board 2190 via an interface (not shown). When the control board 2190 receives the print control command and print data, if RGB is specified in the color specification command, for example, it converts the RGB data to CMYK data using its internal color processing unit, and then drives the print head 2120 to print.

[Comparative Example of Image Processing Device]
FIG. 3 is a diagram for explaining a comparative example of image processing for printing a document generated by a document generation application of the host PC 300. In FIG.

The host PC 300 includes a document generation application 301, which is an application that generates documents. The document generation application 301 transmits a print job for printing the generated document to an image processing device 320, which is a print server. Print output is performed based on this print job. The document also includes objects such as graphics (figures).

The document generation application 301 that creates documents generally has multiple setting items. Three of these setting items, "Color mode" 311, "Color sample settings" 312, and "Color simulation settings" 313, will be explained below.

The first setting item, "Color mode" 311, is used to set the basic color space of the document. When a document is generated for printing, "Color mode" 311 must be set to CMYK mode. When a document is generated for the web rather than for printing, "Color mode" 311 is set to RGB mode. Color mode 311 is generally explicitly specified when creating a new document. In traditional workflows, it was common to select CMYK mode, but in today's world where web design work has increased and CMS functions have become widespread, it is also common to select RGB mode.

Incidentally, color mode 311 also includes the meaning of specifying the color space of the color rendering space in the subsequent image formation stage. Printers normally use CMYK rendering, but there are also systems that develop images in RGB. In either case, the color space is defined, so there is no difference in the reproduced colors. However, there may be differences regarding colors outside the device's color reproduction range.

The following description of the application settings assumes that "RGB" is selected in "Color mode" 311. The second setting item, "Color sample settings" 312, is for selecting either "Use spot color" or "Process color". The document generation application 301 displays a color sample library window (not shown) on the display of the host PC 300. In this window, a list of full-color, solidly painted rectangular shapes (called color samples) for each color is displayed. The user, the designer, can specify a color from the displayed list of color samples. Alternatively, a color can be specified by inputting a color value or adjusting it with a slide bar or the like. Generally, a color is often specified from a list of color samples.

The list of color swatches in the Color Swatch Library window includes spot color swatches that are different from the CMYK process colors. Each spot color swatch also displays the name of the spot color.

When "Use spot colors" is set in the setting item "Color sample settings" 312, a mark indicating that spot colors are available is displayed in each color sample. Therefore, by entering a character string indicating the name of the spot color, the spot color of the selected NAME can be specified. When a document generated with "Use spot colors" set is printed on a printing press that uses plates, such as an offset printing press, a plate for the spot color is added in addition to the plates for each CMYK color.

If "Process color" is set in the setting item "Color sample setting" 312, it is possible to specify a spot color, but the specified spot color will be converted to CMYK values, which are color values in the CMYK color space. When "Process color" is set, a mark indicating that spot colors cannot be used is displayed, so the designer creating the document can confirm that the color (spot color) of the specified NAME will be converted to CMYK values for processing.

The following explanation assumes that the input data is set to "CMYK" in "Color mode" 311, "Use spot colors" in "Color sample settings" 312, and a document print job is input to the image processing device.

The third setting item, "Color Simulation Settings" 313, is used to determine the color settings of the document by selecting either "Color Simulation," "Simple Check," or "Off." "Color Simulation" is selected when specifying the color finish on a target device such as an offset printing press, and simulating and printing out the specified color finish on a digital printer (color proofer), including checking the color reproduction. When "Color Simulation" is selected in the setting item "Color Simulation Settings" 313, the plate composition mode of the digital printer (color proofer) is turned ON.

"Simple Check" is selected when the purpose is to check the layout of objects on the document, etc., without worrying about the accuracy of color reproduction. In the example in Figure 3, "Simple Check" has been selected, so the color separation mode of the digital printer (color proofer) is turned OFF.

Both "Color Simulation" and "Simple Check" use the color profile settings to perform CMS (Color Management System) color conversion processing. On the other hand, if CMS processing is not required and printing is to be performed without using a color profile, "OFF" is selected in the setting item "Color Simulation Settings" 313.

The image processing device 320, which is a print server in the comparative example, receives document data generated by a document generation application in the host PC 300 as input data 351. The input data 351 is, for example, PDL (page description language) data representing a document generated with "CMYK" set in "Color mode" 311 and "Use spot colors" set in "Color sample settings" 312.

First, the process for printing with the printer engine 340 based on the input data 351 in the image processing device 320 will be described. The printer engine 340 refers to a printing machine that performs printing using plates, such as offset printing, flexographic printing, and gravure printing.

The input data 351 is passed to the PDL analysis unit 331. The PDL analysis unit 331 performs a PDL interpreter (analysis of PDL data). After the PDL interpretation, the input data 351 is passed to the intermediate data generation unit 332. The intermediate data generation unit 332 performs drawing processing (contour extraction) and the like. By performing these processes, the input data 351 is converted into data (hereinafter referred to as intermediate data) in a format suitable for the image formation processing in the subsequent stage, such as the data of figures on each page. The intermediate data is sometimes called a display list, etc. The generated intermediate data is temporarily stored in the intermediate data spooler 333. The intermediate data is then transferred to the image formation unit 334 in the subsequent stage.

The image forming unit 334 develops bitmap data (bitmap image data) in memory based on the information of the intermediate data. If the PDL data specifies one spot color, bitmap data for the following number of colors is generated. In other words, when the process of separating the data for each CMYK color and the spot color is performed, bitmap data for at least five colors of each of the CMYK colors and the spot color is generated. The generated bitmap data for each color is also called printing plate data 352 for each color.

The bitmap data (printing plate data 352) expanded in memory is temporarily stored in a bitmap data buffer memory 335. The bitmap data (printing plate data 352) is then transferred to the printer engine 340 via an engine interface (I/F: INTERFACE) unit 336. The intermediate data generation unit 332, image formation unit 334, and engine I/F unit 336 are controlled by the control unit 330.

Next, a comparative example of image processing of input data 351 for printing a printout as a color sample of input data 351 with a color printer 2010 (color proofer) using four color materials of CMYK will be described with reference to FIG. 4. FIG. 4 is a diagram showing an example of color proofing in a printing system of the comparative example. Note that FIG. 4 shows a state in which "color simulation" is selected in "color simulation setting" 313 and the plate separation synthesis mode of the digital printer (color proofer) is ON. As with image processing for printing with the printer engine 340, the input data 351 is processed into intermediate data by the intermediate data generation unit 332, and image formation is performed by the image formation unit 334, and printing plate data 352 of each color is generated. The generated printing plate data 352 of each color is temporarily stored in the plate data spooler 337. The plate data spooler 337 is configured with a disk rather than a memory. Then, the printing plate data 352 of each color is output to the composite color processing unit 338.

The composite color processing unit 338 converts the color values of the printing plate data for the spot color into color values expressed by the process colors. The converted printing plate data for the spot color is then composited with the printing plate data for each process color, converting the printing plate data for each color, including the spot color, into data reproduced by the process colors. As a result of processing by the composite color processing unit 338, the input data 351 is converted into data that matches the color printer 2010 (color proofer), making it possible to output a printed material that serves as a color sample on the color printer 2010 (color proofer).

However, in this comparative example, the processing time is long because printing plate data for the four process colors and at least one spot color generated after the previous image formation process (RIP) is stored. It is also possible to perform a process of combining image data represented by the process colors obtained by separating the input data 351 and image data represented by the spot colors when generating a bitmap image in the image formation process. Even in this case, an area is required to store the image data of the spot colors.

[Processing of the image processing apparatus according to this embodiment]
FIG. 5 is a diagram for explaining the image processing of the present embodiment for input data 551 in order to print a printout as a color sample of the input data 551 with a color printer 2010 (color proofer) using four color materials of CMYK. Note that FIG. 5 shows a state in which "color simulation" is selected in "color simulation setting" 513 and the color separation synthesis mode of the digital printer (color proofer) is ON. The functions of each functional unit of the image processing device 100 shown in FIG. 5 are described as being realized by software, but are not limited to this. In addition, for example, hardware such as a GPU (Graphics Processing Unit) or an FPGA (Field Programmable Gate Array) for accelerating calculations may be used. That is, each functional unit of the image processing device 100 may be realized by cooperation between software and hardware such as a dedicated IC, or some or all of the functions may be realized only by hardware. Furthermore, a configuration may be used in which N image processing devices 100 are used to distribute and execute the processing of each functional unit.

Input data 551, like input data 351 in Figure 4, colors other than spot colors are specified by color values in the CMYK color space, and the input data is PDL data that includes commands to draw objects in spot colors.

Input data 551, which is PDL data, is input to the intermediate data generating unit 532 via the PDL analysis unit 531. The intermediate data generating unit 532 of this embodiment and the intermediate data generating unit 332 of the comparative example are the same in terms of generating intermediate data from the input data 551. The intermediate data generating unit 332 of the comparative example is configured to perform color processing, but in this embodiment, in addition to the processing in the intermediate data generating unit 532, the spot color synthesis processing unit 537 performs spot color synthesis processing that is an extension of color processing to generate intermediate data. Therefore, even if the plates are separated, the color of the area where objects such as figures overlap (overprinted area) can be calculated. Note that the spool processing unit 603 in the intermediate data generating unit 532 temporarily holds the intermediate data generated by the intermediate data generating unit 532 before outputting it to the intermediate data spooler 533. Note that the intermediate data spooler 533 has the same function as the intermediate data spooler 333 described above, and the image forming unit 534 has the same function as the image forming unit 334 described above, so their description will be omitted. In addition, the bitmap data buffer memory 535 has the same functions as the bitmap data buffer memory 335 described above, and the engine I/F 536 has the same functions as the engine I/F 336 described above, so their explanations will be omitted.

Figure 6 is a diagram for explaining the details of the functions of the intermediate data generation unit 532 and the spot color synthesis processing unit 537 of this embodiment. First, input data 551 for printing is received, and the received input data 551 is structurally analyzed by the PDL analysis unit 531 and passed to the intermediate data generation unit 532 via the DRAWING-I/F (INTERFACE). Specifically, the processing is performed as follows.

The PDL analysis unit 531, which is located before the intermediate data generation unit 532, performs structural analysis of the input data 551 (PDL data) and extracts the drawing command (TOKEN) from the input data 551. The PDL analysis unit 531 then outputs the data as a command drawing instruction to the modules (RIP processing unit) below the data receiving unit 601 via DRAWING-IF. In the input data (PDL data), the spot color is specified as a color specification for a separate plate or as a fill color for a figure according to the PDL specifications. The "color specification information" passed from the PDL analysis unit 531 is detected by the data receiving unit 601 of the intermediate data generation unit 532 via DRAWING-IF in FIG. 6. The "color specification information" also includes information for specifying the color of the spot color. In this embodiment, when a color specified as a spot color by the PDL analysis unit 531 is detected, the data receiving unit 601 extracts the detected spot color.

The spot color conversion unit 538 performs color conversion processing to convert the extracted spot colors into data for color synthesis. For example, the extracted spot colors are converted into spectral data or values in the CMY color space (CMY values). In this embodiment, the spot color conversion unit 538 is described as converting spot colors into spectral data. The color conversion method is, for example, to convert using a DB in which spot colors and color synthesis data are associated.

The color synthesis data converted from the spot color is returned to the data receiving unit 601 and passed to the loop processing unit 610, which is the next process, as a paint color specification.

Since information about shapes and other figures is passed from the DRAWING-IF, it is configured to perform edge extraction processing to draw this, and the data is separated into outline information and filling information.

As shown in FIG. 6, for example, each process such as spot color conversion and intermediate data generation processing is configured to be executed in parallel, and an independent thread is assigned by the task control unit 539. In other words, the task control unit 539 executes the spot color conversion processing and the intermediate data generation processing in parallel by assigning threads that can be executed in parallel (multi-threads) to each of the spot color conversion processing and the intermediate data generation processing.

Figure 7 is a diagram for explaining the details of the processing of the data receiving unit 601 and loop processing unit 610 below the DRAWING-I/F. Below the DRAWING-I/F, in the case of figures, processing is performed to separate the data into figure outline information and painting information by figure edge extraction 602.

The data receiving unit 601 receives a graphics drawing command function 701 included in the analysis result by the PDL analysis unit 531. The data receiving unit 601 handles the graphics data as a group of commands called a DL (DISPLAY LIST). Therefore, the data receiving unit 601 creates DL list information, and then executes a process to receive graphics elements.

After this, the data receiving unit 601 executes DL fill path addition processing (function name: FN_ADD_FILL_PATH_ON_MEDIA). In the DL fill path addition processing, an instance for managing various information is generated. The data receiving unit 601 executes DL fill level generation processing to generate an instance for managing the order in which DLs are called (called the level). It also executes DL band subpath entry generation processing to generate band subpath entry information for managing information on a band basis. The data receiving unit 601 also calls DL band entry commit processing to start band processing. It then executes DL internal information update processing to complete the processing.

Next, an overview of the loop processing unit 610 will be described. The loop processing unit 610 extracts edges of figures within a page represented by the command of the input data 551 by performing loop processing on a scan line basis. After the extracted edges are obtained, the edge information is updated and it is determined for each scan line whether edges intersect. If edges intersect, they are processed as multiple figures overlapping. For areas where figures overlap (overlapping areas), the spot color blending processing unit 537 is configured to determine a blending color, which is the color of the overlapping area.

In this embodiment, the page is basically divided into bands. Then, graphic edge extraction is performed from the first band (the band at the top of the page) to the last band (the band at the bottom of the page). Graphics are configured to be manipulated individually within each band.

Next, the specific processing of figure edge extraction 602 by loop processing section 610 will be described. First, new figure edge acquisition processing (function name: FN_GET_NEW_EDGE) is performed within the band to be processed. In new figure edge acquisition processing, DL edge acquisition processing is performed to acquire the edges of figures registered in the DL list, and if an edge is acquired, front-stage edge processing is executed to acquire the edge information required for rear-stage processing. There are multiple types of edges related to figures as PDL specifications, but which one is selected is determined by commands from the PDL. The edge type is specified in the figure drawing in DRAWING-IF. Dedicated functions are provided for each internal processing.

In this embodiment, the case of processing area intersection will be described. When the shape specification is an area intersection, the area intersection processing is initialized. Specifically, the initialization processing for edge processing and the initialization processing for the tracking function are performed. The edge position information update processing is also called first.

In addition, in the figure edge extraction 602, while processing edges to extract contour information of figures, it also extracts rules (winding rules) regarding how figures are painted. For this reason, the winding rule process (function name: FN_WR_EDGE_PROCESS) is called. In the winding rule process, level monitoring, substrip processing for level processing, edge sorting processing for level processing, and updating of edge horizontal information are performed. Note that the edge data extracted in the figure edge extraction 602 is passed to the downstream data synthesis unit 604 as appropriate, and synthesis (overlay processing) on the page is performed.

Figure 8 is a diagram for explaining the processing in the loop processing unit 610 in Figure 7 in more detail. When the PDL graphics drawing command is completed, the end processing (function name: FN_DRAWING_FINISH_PROCESS) is called and the subsequent processing begins. At the same time as the end processing begins, the spool preparation processing (function name: FN_DRAWING_SPOOLDATA_GENERATE) is called, and then the spool start processing (function name: FN_SPOOL_BEGIN) is called. Subsequent processing is executed in units called strips (function name: FN_SPOOLDATA_STRIP_GENERATE). A strip is a processing unit smaller than a band.

The loop processing is executed within the WHILE processing, and the setting information (CONTEXT_DATA) is checked to determine whether any data remains and thus whether the termination condition is met. The loop processing begins with a process (function name: FN_GET_NEW) to check whether there is a new edge in the band being processed. Specifically, the relevant shape is extracted from the object manager (not shown) which stores the shape as DL, and the new edge, which is the edge that overlaps the first scanline, is obtained. A scanline is a processing unit smaller than a strip.

Next, after obtaining a new edge, the edge is updated on the next scan line. This is performed by looping the number of times equal to the required height (HEIGHT). Even when multiple edges are found, the information for each is stored and managed individually. A determination is made for each scan line loop as to whether or not the edges intersect, and a flag is set to indicate the result of this determination. Specifically, if the edges are determined not to intersect, the flag is set to "CLEAN". If the edges are determined to intersect, the flag is set to the value "LEVEL1". Subsequent processing is switched depending on the flag that has been set, and painting information is updated, etc.

Figure 9 is a diagram for explaining each branching process according to the flag that indicates the result of the determination of whether or not an edge crosses. Figure 9(a) shows the case of the first process (no crossing), Figure 9(b) shows the case of crossing, and Figure 9(c) shows the color management stack.

As shown in Figure 9 (a), if the flag is set to CLEAN (edges do not intersect), function name: FN_FAST_PRE_PROCESS is called. If the flag is CLEAN, the fill color of the shape is set to the current color (variable name: ACTIVE_VAL), and then newly registered in the color management stack that manages the object's fill color, as shown in Figure 9 (c). However, if the corresponding color is already registered in the color management stack, the color will not be registered as it would be duplicate information.

On the other hand, as shown in FIG. 9B, if the flag is set to LEVEL1 (edges intersect), function name: FN_SLOW_PRE_PROCESS is called. At this time, if the color separation synthesis mode is set, both the color of the figure to be processed this time and the color of the figure that overlaps with the figure to be processed are passed to the process that sets the synthesis color (function name: FN_SPECIAL_COLOR). This conveys the overlapping state (synthetic color state) to the color management stack. Note that the color separation synthesis mode is set, for example, when the overlapping area is a transparent area. Or, for example, it is set when the plate state is overprint. On the other hand, if the color separation synthesis mode is not set, the color of the figure to be processed this time is set as the current color (variable name: ACTIVE_VAL), and then newly registered in the color management stack shown in FIG. 9C. However, if the corresponding color has already been registered in the color management stack, the color will not be registered because it will be duplicated information.

Figure 10 is a diagram for explaining the spot color compositing process. Figure 10(a) shows an overview of the spot color compositing process. Figure 10(b) shows a state where an edge 1001 of a shape in which the CMYK value "purple", which is the color value of the process color, is specified as the paint color, intersects with an edge 1002 of a shape in which the spot color "RED PURPLE" is specified as the paint color. In this case, in the shape edge extraction 602, the flag is set to LEVEL1. Furthermore, when the color separation compositing mode is set, information on both the process color, which is the color of one of the overlapping shapes, and the spot color "RED PURPLE", which is the color of the other shape, is registered in the color management stack. Furthermore, the fact that these two colors are in a composite state is communicated to the color management stack.

As shown in FIG. 10B, when it is determined that there is an area where a shape with an edge overlaps with another shape with an edge and the colors are mixed, if the color separation mode is set, it is necessary to simulate the composite color when overprinted. For this reason, in this embodiment, if the paint color of a shape that overlaps with a spot color shape is specified in CMYK values in the input data 551, the CMYK values are also converted into color blending data. In this embodiment, the color blending data is described as CMY values, which are color values in the CMY color space. In this embodiment, the CMYK values and spot colors, which are the color values of the two overlapping shapes, are each mapped to LAB values and converted into CMY values for color blending. In this embodiment, the color of the ink is defined as coming from the characteristics of the spectral colors, and the composite color is determined by converting to CMY values.

In the figure, the CMYK values are colors in the specified color space (the setting profile is STANDARD-COLOR) and are specified as the color to paint inside the edges. In this case, it is the color "purple." Also, for spot colors, the color value is defined by name, and LAB values etc. can be directly referenced. In this example, the color is "red purple," and the name is specified as the string "RED PURPLE."

In this embodiment, because it is necessary to simulate overprinting in the color separation mode, each spot color is mapped to an LAB value and then converted into spectral data for the composite color. The spot color synthesis processing unit 537 synthesizes the two converted spectral data to obtain spectral data representing the composite color of the two colors (deep purple in FIG. 10). The method of synthesizing the spectral data is, for example, the method described in Patent Document 1.

Figure 11 is a diagram for explaining the spectral DB 1010 in which the spectral data of the composite color is stored. To check the state of color mixing of two colors, as shown in Figure 11, a patch of mixed colors is printed by gradually changing the density of each color. Ideally, it is preferable to print using the combination of the printing machine and recording paper to be color-calibrated, but approximately it is also possible to print using a combination of another printer and general-purpose recording paper.

When the density of each spot color is changed in 25% increments between 0% and 100%, five patches are obtained for each spot color, and a sample chart 1101 with 25 patches is created by combining two spot colors. Then, by measuring the sample chart 1101 with a colorimeter 1102, for example, every 5 nm or 10 nm in the visible range, it is possible to obtain spectral data 1103 indicating the spectral reflectance in the visible range for the combination of the density values of the two spot colors. Of course, the spectral data between the density values of each patch can also be found by performing an interpolation calculation of the spectral data.

As explained above, the image processing device of this embodiment is configured to perform image formation assuming plates containing spot colors at the image formation stage of PDL processing. In other words, spot color processing such as color conversion processing for spot colors is treated as processing below the drawing IF. This makes it possible to assign CMS processing to tasks on the parallel RIP side, enabling high-speed processing even for jobs containing a large amount of spot colors. It supports combinations of CMYK and spot colors as colors to be combined in color separation combinations.

As shown in FIG. 5 and subsequent figures, input data for printing is received, and the data resulting from the analysis of the received input data by the PDL analysis unit 531 is passed to the drawing system via the drawing IF, and the edges of the figure are extracted by loop processing on a scan line basis. After obtaining the extracted edges, the edge information is updated. Then, for each scan line, it is determined whether the edges intersect, and the determination result is stored in a flag. Branching processing is executed according to the flag condition. If the flag stores the determination result that the edges intersect, it is determined that the figures overlap, and the spot color synthesis processing unit 537 calculates a synthesis color for the overlapping area. If a spot color is specified for the color of the figure, it is converted into color space data (spectral data) for calculating the synthesis color, and the spectral data is stored in the color management stack of the spectral database (spectral DB) 1010.

The composite color of the overlapping area is calculated by a spot color blending process while referencing the colors stored in the color management stack.

Therefore, according to this embodiment, the load when simulating spot colors can be reduced. In other words, even if a print job includes an object with a spot color specified, a means is provided for efficiently extracting the area where the object with the spot color specified overlaps with another object (any color specified). This makes it possible to achieve faster image formation processing even when performing color separation and compositing processing. In particular, when high resolution is specified and output is made on large paper, such as in commercial printing, and even when there is a large amount of complex data such as graphics in the print page, image formation can be performed extremely quickly.

<Embodiment 2>
In the first embodiment, a method for determining a composite color of an area where a CMYK color plate specified by CMY values expressed in a CMY color space and a spot color plate overlap based on a command in PDL data is described. In this embodiment, a method for determining a composite color from PDL data when a printing plate of a color specified by RGB values expressed in an RGB color space and a spot color plate overlap is described. In addition, in this embodiment, a process for performing a composite calculation when a specified color is a color outside the color reproduction range of the printer is described. In this embodiment, differences from the first embodiment are mainly described. Parts not specifically described have the same configuration and process as the first embodiment. For example, the configuration of the image processing device of this embodiment is basically the same as the configuration of the image processing device 100 of FIG. 5 of this embodiment.

Figure 12 is a diagram similar to Figure 10, and is an overview diagram for explaining the state in which edges intersect. Unlike Figure 10 in the first embodiment, Figure 12 shows the state in which the edge of a shape whose fill color is specified by RGB values rather than a special color intersects with the edge of a shape whose fill color is specified by the special color "BLUE PURPLE."

In this embodiment, the color separation mode is selected, and in this case it is necessary to simulate overprinting as a rendering process. To perform this process, the RGB values and spot colors must each be converted into the color space CMY for the composite color. The manner in which each color is converted into a CMY value for the composite color will be described later with reference to figures.

In this embodiment, RGB values are also converted to CMY values in the same way. However, when a color space such as HDTV or sRGB is defined as the definition of RGB values, these colors include the color gamut of the display. Ideally, the application that performs color specification should specify colors limited to those within the color reproduction range of the print color, but it is generally assumed that the specifications for the use case are not defined. Even if a method of limiting colors is considered, there are aspects in which it is difficult to strictly determine whether a color is inside or outside the color reproduction range, and it becomes necessary to assume either case and perform color reproduction, even if only simulated, on the image forming device side.

Therefore, in this embodiment, a process is performed to map the specified RGB value (p1) to an RGB value (p1') within the printer gamut. By performing the mapping process, the color (RGB value) on the print color and the spot color can be combined.

Figure 13 is a diagram to explain how to find a composite color (CMY3) from two colors (CMY1 and CMY2) using the color mixing DB in Figure 12.

As mentioned in the previous example, when RGB values are specified, mapping is performed based on the specified color reproduction range information (GBD = GAMUT BOUNDARY DESCRIPTION). The colors mapped by the mapping process are converted to CMY values (CMY2 of IN2 in Figure 13).

The mixed color DB shown in Figure 13 includes the color values when two colors (CMY1 and CMY2) overlap. The DB is created by printing an actual printed matter and measuring the colors.

The CMY used in Figure 13 refers to process color inks that are generally used in offset printing machines. For example, the input values for the ink combinations are C (cyan), M (magenta), and Y (yellow), with densities of 0%, 0%, and 0% (hereafter referred to as "CMY = 0% 0% 0%). To measure the mixed color (composite color), a patch (rectangular monochromatic coating) is printed using an offset printing machine (lithographic printing) to obtain the color value of the topcoat, CMY = 0% 0% 0%, when the topcoat color value overlaps. By measuring the color of this patch, the CMY values of the composite color corresponding to multiple CMK values can be obtained, and the combination of CMY values of the composite color corresponding to multiple CMY values is stored in the mixed color DB.

If the density (also known as the spacing between grid points on the LUT) is set to a specified value, for example 20%, the input colors for the next patch are CMY=0%0%0% and CMY=0%0%20%, which are printed on top of each other to generate each patch. With this combination, the number of patches is 46,656 colors. In the case of offset printing machines, the total ink amount can generally be set up to 300%, although this depends on the environment. In addition, although the input color combination is specified by CMY, undercolor removal and nonlinear density curves can be used to reduce the total ink amount. In any case, by printing with parameters that are based on the actual printing machine to be used, it becomes possible to simulate color reproduction with higher accuracy.

The color mixing DB 1210 is configured as a multidimensional LUT, and colors located in the intervals between each patch color can be found by the interpolation calculation that is widely used in CMS processing. For example, for a composite color of CMY = 0% 0% 0% and CMY = 0% 0% 15%, the surrounding grid points are found, the output values on those grid points are referenced, and then linear interpolation calculations are performed based on those values while sequentially reducing the dimensions to find the final value.

The top diagram in Figure 13 shows mixed color patches CMY00, CMY01, CMY10, and CMY11 obtained by gradually changing the density of the two colors to be mixed. "CMY0", "CMY1", and "CMYn" represent a change in density from 0% to 100%, while CMY00, CMY01, CMY10, and CMY11 represent patches where the density of the second color is 0%, 25%, 50%, and 100%, respectively. Note that the change in density does not have to be in the same increments for both colors to be mixed.

The diagram at the bottom of Figure 13 is an overview diagram showing how to find the CMY value of a composite color (CMY3) from two CMY values (CMY1 and CMY2). For example, if the CMY value of CMY1 is (128, 10, 3) and the CMY value of CMY2 is (5, 160, 2), then by using the color mixing DB, the CMY value of the composite color CMY3 is obtained as (134, 150, 5).

As described above, in the image processing device of this embodiment, when a spot color is specified as the shape color, it is converted into color space data for calculating the composite color (CMY color space data for composite), and this is configured to be saved in the color management stack.

Therefore, this embodiment can reduce the load when simulating spot colors.

<Other embodiments>
In the above, the combination of CMYK and spot colors and the combination of RGB and spot colors are described as the target colors in the color separation composition, but the present invention is not limited to this. It is also possible to use all combinations of CMYK, RGB, and spot colors as the target colors in the color separation composition.

The present disclosure can also be realized by supplying a program that realizes one or more of the functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that realizes one or more of the functions.

＜Other＞
The disclosure of the above-described embodiment includes the following configurations.

(Configuration 1)
an analysis means for analyzing PDL data in which color values of objects in a page are specified;
a conversion means for converting, based on the analysis result obtained by the analysis means, color values of one of the first object and the second object overlapping on the page, which is designated as a spot color, into color synthesis data;
a first determination means for determining a composite color, which is a color of an area where the first object and the second object overlap, based on the color composition data converted by the conversion means;
a generating means for generating bitmap image data in which the blended color and the spot color are expressed by process colors;
13. An image processing device comprising:

(Configuration 2)
2. The image processing apparatus according to configuration 1, further comprising a control means for causing the conversion process by said conversion means and the generation process by said generation means to be executed in parallel.

(Configuration 3)
3. The image processing device according to configuration 2, wherein the control means executes the conversion process and the generation process in parallel by allocating threads that can be executed in parallel to each of the conversion process and the generation process.

(Configuration 4)
4. The image processing device according to any one of configurations 1 to 3, wherein, in the PDL data, the color value of the first object is specified by a CMY value represented in a CMY color space, and the color value of the second object is specified by a spot color.

(Configuration 5)
the color synthesis data is spectral data,
5. The image processing apparatus according to configuration 4, wherein the first determining means determines the composite color by combining the converted spectral data.

(Configuration 6)
4. The image processing device according to any one of configurations 1 to 3, wherein, in the PDL data, a color value of the first object is specified by an RGB value represented in an RGB color space, and a color value of the second object is specified by a spot color.

(Configuration 7)
the color synthesis data is a CMY value expressed in a CMY color space, converted from the RGB value;
7. The image processing apparatus according to configuration 6, wherein the first determining means determines the composite color based on the CMY values.

(Configuration 8)
The image processing device according to configuration 7, wherein the first determination means determines the composite color by identifying a CMY value converted from the RGB value of the first object and a CMY value converted from a color value of the spot color of the second object using a multidimensional database that holds CMY values corresponding to a plurality of CMY values.

(Configuration 9)
9. The image processing device according to configuration 8, wherein the database is a database obtained by measuring each patch representing a mixture of two colors obtained by changing the density of two CMY values by a predetermined value.

(Configuration 10)
The method further includes a management unit for managing the color of the object in the page obtained by analyzing the PDL data,
10. The image processing device according to any one of configurations 1 to 9, wherein the first determining means determines the composite color by referring to the colors managed by the managing means.

(Configuration 11)
11. The image processing device according to any one of configurations 1 to 10, further comprising: a second determination means for determining the area where the first object and the second object overlap based on a result of the analysis.

(Configuration 12)
The second determination means includes:
12. The image processing apparatus according to configuration 11, wherein the area is determined by extracting an edge of an object based on a command of the PDL data.

(Configuration 13)
13. The image processing apparatus according to any one of configurations 1 to 12, wherein the generating means generates printing plate data for each color corresponding to the process color.

(Configuration 14)
an analysis step of analyzing PDL data in which color values of objects in a page are specified;
a conversion step of converting color values of one of the first object and the second object overlapping on the page, the color values being designated as a spot color, into color synthesis data based on the analysis result obtained in the analysis step;
a first determination step of determining a composite color, which is a color of an area where the first object and the second object overlap, based on the color composition data converted in the conversion step;
a generating step of generating bitmap image data in which the blend color and the spot color are expressed by process colors;
13. An image processing method comprising:

(Configuration 15)
A program for causing a computer to execute each of the means of the image processing device according to any one of configurations 1 to 13.

100 Image processing device 531 PDL analysis unit 532 Intermediate data generation unit 537 Special color synthesis processing unit 538 Special color conversion unit

Claims (15)

an analysis means for analyzing PDL data in which color values of objects in a page are specified;
a conversion means for converting, based on the analysis result obtained by the analysis means, color values of one of the first object and the second object overlapping on the page, which is designated as a spot color, into color synthesis data;
a first determination means for determining a composite color, which is a color of an area where the first object and the second object overlap, based on the color composition data converted by the conversion means;
a generating means for generating bitmap image data in which the blended color and the spot color are expressed by process colors;
13. An image processing device comprising: 2. The image processing apparatus according to claim 1, further comprising a control unit for causing the conversion process by said conversion unit and the generation process by said generation unit to be executed in parallel. The image processing device according to claim 2 , wherein the control means executes the conversion process and the generation process in parallel by allocating threads that can be executed in parallel to each of the conversion process and the generation process. 2 . The image processing apparatus according to claim 1 , wherein, in the PDL data, the color value of the first object is specified by a CMY value expressed in a CMY color space, and the color value of the second object is specified by a spot color. the color synthesis data is spectral data,
5. The image processing apparatus according to claim 4, wherein the first determining means determines the composite color by combining the converted spectral data. 2. The image processing apparatus according to claim 1, wherein, in the PDL data, the color value of the first object is specified by an RGB value represented in an RGB color space, and the color value of the second object is specified by a spot color. the color synthesis data is a CMY value expressed in a CMY color space, converted from the RGB value;
The image processing apparatus according to claim 6 , wherein the first determining means determines the composite color based on the CMY values. 8. The image processing device according to claim 7, wherein the first determination means determines the composite color by identifying a CMY value converted from the RGB value of the first object and a CMY value converted from a color value of the spot color of the second object using a multidimensional database that holds CMY values corresponding to a plurality of CMY values. 9. The image processing apparatus according to claim 8, wherein the database is a database obtained by measuring each patch representing a mixture of two colors obtained by changing the density of each of the two CMY values by a predetermined value. The method further includes a management unit for managing the color of the object in the page obtained by analyzing the PDL data,
2. The image processing apparatus according to claim 1, wherein the first determining means determines the composite color by referring to the colors managed by the managing means. The image processing apparatus according to claim 1 , further comprising a second determination unit that determines the area where the first object and the second object overlap based on the analysis result. The second determination means includes:
The image processing apparatus according to claim 11, wherein the area is determined by extracting an edge of an object based on a command of the PDL data. The image processing apparatus according to claim 1 , wherein the generating means generates printing plate data for each color corresponding to the process color. an analysis step of analyzing PDL data in which color values of objects in a page are specified;
a conversion step of converting color values of one of the first object and the second object overlapping on the page, the color values being designated as a spot color, into color synthesis data based on the analysis result obtained in the analysis step;
a first determination step of determining a composite color, which is a color of an area where the first object and the second object overlap, based on the color composition data converted in the conversion step;
a generating step of generating bitmap image data in which the blend color and the spot color are expressed by process colors;
13. An image processing method comprising: A program for causing a computer to execute each of the means of the image processing device according to any one of claims 1 to 13.

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