JP2023134195A - Image processing apparatus, image processing method, and program - Google Patents

Abstract

To prevent occurrence of mismatch of drawing colors in a same page in printing color data in a monochrome mode.SOLUTION: A page analysis unit reads a drawing instruction and generates intermediate data on the basis of, the drawing instruction. A color conversion unit generates a color conversion table for density enhancement. The page analysis unit determines whether to perform fallback processing because the generated intermediate data does not fall within an intermediate data storage area of a RAM. In performing the fallback processing, a color conversion method setting unit sets and changes a color conversion method from "density enhancement" to "gray-scaling all colors." An image processing control unit temporarily renders the intermediate data stored in the RAM, and registers raster image data after the rendering in the intermediate data unable to be stored in the RAM as a background image. The image processing control unit performs color conversion by using the color conversion unit, and generates the raster image data on the basis of the intermediate data for one page.SELECTED DRAWING: Figure 3

Description

The present invention relates to an image processing technique for monochrome printing of color data.

When an image forming apparatus outputs a color original in grayscale format that includes multiple colors represented by multiple color components, such as in RGB format, the input RGB values are generally converted to include all color values. It is converted into a gray value using a uniform conversion formula (such as NTSC conversion) and output. Color conversion performed on all color values (hereinafter referred to as all-color color conversion) is effective for documents requiring gradation.

On the other hand, there is a color conversion method that narrows down the conversion target to the colors used within the same page of the original and sets the gray density value interval as large as possible according to the density value of each color and the number of colors used on each page. Proposed. This method is effective for manuscripts that include graphs and the like in which distinguishability between color-coded elements is important. Patent Document 1 discloses a technique for rewriting a color table used in intermediate data before starting rendering, based on a color conversion table for one page generated by analyzing PDL data.

Japanese Patent Application Publication No. 2020-49939

By the way, in an image forming apparatus, if a memory overflow occurs while generating intermediate data for one page, a fallback process is performed that temporarily renders the intermediate data generated so far and generates the remaining intermediate data as other intermediate data. It will be done. However, in the technology of Patent Document 1, fallback processing is performed, and when raster image data is generated from intermediate data up to the middle of the page, a mismatch in drawing color may occur with raster image data generated after that. There is. This is because the colors set in the color conversion table are added sequentially during the process of generating intermediate data, so when setting gray value intervals based on the number of colors, for example, in the middle of a page and on the entire page, the color conversion table is This is because the number of colors set changes and the gray value also changes.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent mismatching of drawn colors on the same page when printing color data in monochrome.

The present invention is an image processing apparatus that generates raster image data for printing based on PDL data included in a print job for printing color data in monochrome,
an analysis means for analyzing the PDL data to generate intermediate data for each drawing command and sequentially storing the generated intermediate data in a storage device; and a plurality of colors represented by a plurality of color components specified in the PDL data. color conversion means for converting each density value into a single color density value using a color conversion method specified in the print job; and a first color conversion means for improving distinctiveness as the color conversion method in the print job. When a color conversion method is specified and the intermediate data obtained while the analysis means is generating one page of intermediate data cannot be stored in the storage device, the color conversion method is a setting means for setting a second color conversion method different from the first color conversion method; and a setting means for setting a second color conversion method different from the first color conversion method; An image processing means for generating raster image data.

According to the present invention, when color data is printed in monochrome, it is possible to prevent mismatching of drawn colors within the same page.

FIG. 1 is a block diagram showing an example of a hardware configuration of an image forming apparatus. 1 is a diagram illustrating an example of a software configuration of an image forming apparatus. It is a flowchart which shows DL generation processing in a 1st embodiment. 7 is a flowchart showing fallback processing and image forming processing in the first embodiment. It is a flowchart which shows DL generation processing in a 2nd embodiment. 7 is a flowchart showing image forming processing in a second embodiment. It is a flowchart which shows DL generation processing in a 3rd embodiment. 7 is a flowchart showing image forming processing in a third embodiment. It is a flowchart which shows DL generation processing in a 4th embodiment. 12 is a flowchart showing fallback processing and image forming processing in a fourth embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated using drawings. Note that the constituent elements described in the following embodiments represent exemplary embodiments of the present invention, and the scope of the present invention is not limited thereto.

<First embodiment>
DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment for carrying out the present invention will be described below with reference to the drawings. The first embodiment acquires the number of colors used for each page of print data, and switches the color conversion method when the number of colors exceeds a predetermined number.

FIG. 1 is a diagram showing an example of the configuration of a printing system to which the present invention is applied. In this system, a host computer 101 and an image forming apparatus 110 are connected via a LAN 102. A user generates PDL data indicating page information to be printed in the host computer 101, and transmits it from the host computer 101 to the image forming apparatus 110 via the LAN 102. The image forming apparatus 110 in this embodiment may be either an MFP (Multi Function Printer) or an SFP (Single Function Printer). Furthermore, the image forming apparatus 110 may be a printer other than an MFP or an SFP.

[About the hardware configuration of the image forming apparatus]
An example of the hardware configuration in the image forming apparatus 110 of the first embodiment will be described using FIG. 1. The image forming apparatus 110 is, for example, an image output device, and includes a printer section 111 that forms an image on a recording medium. The image forming apparatus 110 also obtains PDL data (print data written in a page description language) from the host computer 101 via the LAN.

The printer unit 111 is connected to the device I/F 235 and performs a process of outputting image data generated by the CPU 220 onto a sheet (paper). The CPU 220 is a central processing unit for controlling the entire image forming apparatus 110 (each part). The RAM 222 is a system work memory for the CPU 220 to operate. In addition, the RAM 222 is used to temporarily store acquired PDL data, intermediate data generated for image forming processing, a work area that is a work area when performing rendering processing, and input image data. It's also memory. The ROM 221 is, for example, a boot ROM, and stores a system boot program. The storage unit 223 is, for example, a hard disk drive, and stores system software for various processes and acquired PDL data.

The operation unit I/F 225 is an interface unit for the operation unit 113 that has a display unit for displaying various menus, information regarding print data instructed to be printed, etc., and outputs operation screen data to the operation unit 113. Further, the operation unit I/F 225 transmits information input by the user via the operation unit 113 to the CPU 220. The network I/F 226 is an interface for exchanging information with an external device (for example, the host computer 101) via the LAN 102. These CPU 220 , ROM 221 , RAM 222 , storage section 223 , operation section I/F 225 , and network I/F 226 are connected to a system bus 227 .

The image bus I/F 228 is an interface for connecting the system bus 227 and the image bus 230 that transfers image data at high speed, and is a bus bridge that converts data structure. A RIP (raster image processor) 231, an image editing section 232, an image compression section 233, an image decompression section 234, and a device I/F 235 are connected to the image bus 230. These are hardware controlled by the CPU 220, but a configuration in which they are controlled by a sub-processor that can execute a program having instructions different from the CPU 220 is also possible.

The RIP 231 analyzes the PDL data code and intermediate data (display list, DL) based on instructions from the CPU 220, and develops it into raster image data for printing. In addition to the raster image data, the RIP 231 generates attribute data indicating which object, such as a character, a line, a graphic, an image, or a background, each pixel of the raster image data corresponds to.

The image editing unit 232 performs pixel-by-pixel image editing such as color space conversion and contour correction on the raster image data developed by the RIP 231.

The image compression unit 233 compresses an image obtained by image expansion by the RIP 231 in accordance with print processing, and stores the compressed image in the RAM 222 via the image bus I/F 228.

The image decompression unit 234 decompresses the image stored in the RAM 222 and transfers the decompression result to the RIP 231 and device I/F 235 via the image bus 230 according to print processing. The image compression section 233 and the image expansion section 234 are used to save the raster image data after expansion by the RIP 231 when the user specifies box storage, and to print the data according to the user's instructions. Further, when the rasterization processing by the RIP 231 is faster than the printing processing by the printer unit 111, it may be used for temporary storage.

The device I/F 235 is an interface for transmitting data to the printer unit 111.

FIG. 2 is a diagram showing an example of the configuration of software modules that the CPU 220 expands from the ROM 221 and the storage unit 223 to the RAM 222 and executes in the image forming apparatus 110 according to the present invention.

The data input unit 201 is a module that receives print data from the host computer 101 via the network I/F 226 and the LAN 102.

The job analysis unit 202 is a module that analyzes and acquires the settings of the module shown in FIG. It is. More specifically, print setting information that specifies PDL data such as PJL (Printer Job Language) and JDF (Job Definition Format), a color conversion method, etc. included in the print data is acquired and analyzed.

The page analysis unit 203 is a module that analyzes information for each page. Specifically, the page description language (PDL) included in the print data is acquired, the drawing commands included in each page are analyzed, and intermediate data is generated.

The image processing control section 204 is a module that controls the RIP 231, the image editing section 232, the image compression section 233, and the image expansion section 234.

The printer control unit 205 is a module that controls the device I/F 235 and the printer unit 111.

The color information acquisition unit 211 is a module that acquires settings related to color processing included in print data. Therefore, in addition to the settings shown in FIG. 2, the settings also include designation of the gamma correction value and the ICC profile to be used, but their description will be omitted in this embodiment.

The color conversion method setting unit 212 is a module in which the page analysis unit 203 analyzes information regarding drawing colors from drawing instructions for each page. In the first embodiment, a case will be described in which the color values and the number of color values used within a page are to be analyzed. Note that the color value is the density value of a color represented by a plurality of color components.

The color conversion unit 213 converts the color values of the used color table of the intermediate data based on the analysis result of the color information acquisition unit 212 and the color conversion table for density emphasis or the conversion formula for converting all colors to gray scale. This is a module that performs the conversion. Note that the color conversion table for density emphasis is generated by the color conversion unit 213 when "density emphasis" is set as the color conversion method. Furthermore, when "grayscaling of all colors" is set as the color conversion method, the color conversion unit 213 converts the color values of the used color table based on a color conversion formula specified in advance. Note that in this disclosure, a configuration in which a color value specified in PDL data is converted into a gray value will be described as an example, but in the case of color monochrome conversion, a configuration in which the color value specified in PDL data is converted to a single color other than gray may be used.

The above is the software module configuration in the first embodiment, but it is of course possible to have a configuration in which submodules exist within each module. Hereinafter, processing from data input to output to the printer unit 111 in the first embodiment will be explained using a flowchart.

FIG. 3 shows the process of switching the color conversion method to grayscale for all colors when fallback processing is performed in a print job in which density emphasis is set as the color conversion method for monochrome printing in the first embodiment. A flowchart for explanation is shown.

In S301, the job analysis unit 202 reads a job start command from print data included in the print job acquired by the data input unit 201. Next, the job analysis unit 202 uses the color information acquisition unit 211 to read the color mode setting command. Only the processing when the print job requires conversion to gray data based on the result read by the color information acquisition unit 211 and when "density emphasis" is set as the color conversion method will be described. If the designation is other than that, the description is omitted because it is the same as the conventional technology.

In S302, the page analysis unit 203 reads a page start command. At this time, the color conversion method for the page is set to "density emphasis". Further, the count of the number of colors in the page, which is necessary for density emphasis processing, is initialized to 0.

In S303, the page analysis unit 203 reads a drawing command.

In S304, if the color conversion method is "density emphasis" and the drawing command read in S303 is a command related to drawing within the page, such as a fill color specification command, the page analysis unit 203 determines the content of the command. The color conversion method setting unit 212 is informed, and the process moves to S305. If the color conversion method is not "density emphasis" or if the drawing command read in S303 is not a command related to drawing within the page, the process moves to S313.

In S305, the color conversion method setting unit 212 counts the number of colors used from the drawing command related to color specification read by the page analysis unit 203. Note that at this time, colors that have been counted once within the same page are not counted in the number of colors even if the same color appears thereafter.

In S306, the color conversion method setting unit 212 determines whether the number of colors used within the page exceeds a predetermined threshold. More specifically, in cases where the total number of colors exceeds the number of gradations of gray data that can be expressed by the printer unit 111, it is determined whether the color data can be converted to gray data with a visible density difference. do. If the number of colors used is less than or equal to the predetermined threshold, the process moves to S307, and if the number of colors used exceeds the predetermined threshold, the process moves to S308.

In S307, the color conversion unit 213 generates a color conversion table for density emphasis. Since the color conversion table is a prior art, its explanation will be omitted.

In S308, the color conversion method setting unit 212 changes the setting of the color conversion method from "density emphasis" to "grayscaling for all colors." Due to this change in the color conversion method, the color conversion unit 213 no longer generates a color conversion table for density emphasis.

In S309, the page analysis unit 203 generates intermediate data based on the drawing command. Specifically, drawing commands and registered characters (fonts) expressed in relative coordinates and Bezier curves are converted into path point sequences in absolute coordinates that match the actual output resolution and paper size.

In S310, the page analysis unit 203 determines whether to perform fallback processing because the intermediate data obtained during generation of one page of intermediate data does not fit within the intermediate data storage area of the RAM 222. . If fallback processing is not performed, the converted intermediate data is sequentially stored in the RAM 222, the process returns to S303, and the next drawing command is read. If fallback processing is to be performed, the process moves to S311.

In S311, the color conversion method setting unit 212 changes the setting of the color conversion method from "density emphasis" to "grayscaling for all colors." Due to this change in the color conversion method, the color conversion unit 213 no longer generates a color conversion table for density emphasis. When performing fallback processing, a log indicating that "density emphasis" has been canceled and "grayscale conversion for all colors" has been changed as a result of the fallback processing is executed, and the configuration also notifies the user. I do not care.

In S312, the image processing control unit 204 executes a fallback process in which the intermediate data stored in the RAM 222 is rendered once, and the rendered raster image data is registered as a background image in the intermediate data that could not be stored in the RAM 222. do. At this time, rendering of the intermediate data stored in the RAM 222 that is less than one page's worth of intermediate data is performed by converting the color values of the color table used into gray values calculated using the color conversion formula for "grayscaling for all colors". Based on this. Then, an area for storing the intermediate data is secured in the RAM 222, and the intermediate data in which the rendered raster image data that could not be stored in the RAM 222 is registered as a background image is sequentially stored in the RAM 222, and the process returns to S303 for the next step. Load the drawing instructions for. As a method for securing an area for storing intermediate data in the RAM 222, rendered intermediate data may be deleted or overwritten. Details of S312 will be described later using the flowchart shown in FIG. 4(a).

In this way, as long as the color conversion method is "density emphasis" and the drawing command read in S303 is a command related to drawing within the page, the processes from S303 to S312 are repeated. Then, if the color conversion method is not "density emphasis" or if the drawing command read in S303 is not a command related to drawing within the page, the process moves to S313.

In S313, the page analysis unit 203 determines whether the drawing command read in S303 is a page break command. If it is a page break command, the process moves to S314; if it is not a page break command, the process moves to S315.

In S314, the page analysis unit 203 adds a job end command indicating the end of the page to the intermediate data, and notifies the image processing control unit 204 and the RIP 231 of one page's worth of intermediate data and the color conversion method.

In S315, the image processing control unit 204 generates raster image data based on the notified intermediate data for one page, and returns to S302. Details of S315 will be described later using the flowchart shown in FIG. 4(b).

In S316, the page analysis unit 203 determines whether the drawing command read in S303 is a job end command. If it is a job end command, the process advances to S316; if it is not a job end command, the process advances to S309. Transition.

In S317, the page analysis unit 203 notifies the job analysis unit 202 that intermediate data conversion for all pages included in the print job has been completed, and ends this sequence.

FIG. 4A shows a flowchart illustrating fallback processing by the image processing control unit 204 according to the first embodiment.

In S411, the image processing control unit 204 acquires the storage location of the intermediate data and the color conversion table, and the color conversion method to be executed. Note that when fallback processing is performed in this embodiment, the color conversion method is set to "grayscale conversion for all colors."

In S412, the image processing control unit 204 uses the color conversion unit 213 to convert the color values of the used color table of the intermediate data based on the color conversion formula for converting all colors to gray scale.

In S413, the image processing control unit 204 uses the RIP 231 to generate raster image data matching the output resolution and paper size based on the intermediate data and the grayscaled color table.

In S414, the image processing control unit 204 registers the raster image data generated in S413 as a background image in the intermediate data that could not be stored in the RAM 222, and stores the raster image data in the RAM 222 in place of the generated intermediate data. .

FIG. 4B shows a flowchart illustrating raster image data generation processing using the RIP 231 of the image processing control unit 204 that has received notification of one page's worth of intermediate data and a color conversion method.

In S421, the image processing control unit 204 acquires the storage location of the intermediate data and color conversion table, and the color conversion method to be executed.

In S422, the image processing control unit 204 determines the set color conversion method, and if "density emphasis" is set, the process moves to S423, and if "grayscale conversion for all colors" is set, the process proceeds to S423. The process moves to S424.

In S423, the image processing control unit 204 uses the color conversion unit 213 to acquire a color conversion table for density emphasis of the color conversion result, and uses the acquired color conversion table to change the color values of the color table used in the intermediate data. Convert.

In S424, the image processing control unit 204 uses the color conversion unit 213 to convert the color values of the color table used in the intermediate data based on the color conversion formula for converting all colors to gray scale.

In S425, the image processing control unit 204 uses the RIP 231 to generate raster image data matching the output resolution and paper size based on the intermediate data and the grayscaled color table.

The above is the raster image data generation process of the image processing control unit 204 that has been notified of the intermediate data for one page and the color conversion method, and these processes are performed using the intermediate data generated by the page analysis unit 203 executed by the CPU 220. is executed by the RIP 231. Therefore, the job analysis and page analysis shown in FIG. 3 operate in parallel with the raster image data generation process shown in FIG. 4.

With these processes, when fallback processing is performed for a print job in which density emphasis is set as the color conversion method, mismatching of drawn colors can be prevented by canceling the density emphasis color conversion process.

<Second embodiment>
A second embodiment for carrying out the present invention will be described below with reference to the drawings. In the second embodiment, when a fallback occurs in a print job in which density emphasis is set, the process is switched to grayscale for all colors and edge emphasis for recovery. Note that the configuration of the print control device of the second embodiment is similar to the configuration of the first embodiment shown in FIG. Below, points different from the first embodiment will be explained.

FIG. 5 shows that in a print job in which density emphasis is set as the color conversion method for monochrome printing according to the second embodiment, the color conversion method is switched to grayscale for all colors when fallback processing is performed, and A flowchart illustrating processing for performing contour enhancement processing is shown.

In S501, the job analysis unit 202 reads a job start command from the input data acquired by the data input unit 201. Next, the job analysis unit 202 uses the color information acquisition unit 211 to read the color mode setting command. Only the processing when the print job requires conversion to gray data based on the result read by the color information acquisition unit 211 and when "density emphasis" is set as the color conversion method will be described. If the designation is other than that, the description is omitted because it is the same as the conventional technology.

In S502, the page analysis unit 203 reads a page start command. At this time, "density emphasis" is set as the color conversion method for the page. Further, the count of the number of colors in a page, which is necessary for density emphasis processing, is initialized to 0.

In S503, the page analysis unit 203 reads a drawing command.

In S504, if the color conversion method is "density emphasis" and the drawing command read in S503 is a command related to drawing within the page, such as a fill color specification command, the page analysis unit 203 determines the content of the command. The color conversion method setting unit 212 is informed, and the process moves to S505. If the color conversion method is not "density emphasis" or if the drawing command read in S903 is not a command related to drawing within the page, the process moves to S913.

In S505, the color conversion method setting unit 212 counts the number of colors used from the drawing command related to color specification read by the page analysis unit 203. Note that at this time, colors that have been counted once within the same page are not counted in the number of colors even if the same color appears thereafter.

In S506, the color conversion method setting unit 212 determines whether the number of colors used within the page exceeds a predetermined threshold. More specifically, in cases where the total number of colors exceeds the number of gradations of gray data that can be expressed by the printer unit 111, it is possible to convert color data into gray data with visible density differences. Determine whether If the number of colors used is less than or equal to the predetermined threshold, the process moves to S507, and if the number of colors used exceeds the predetermined threshold, the process moves to S508.

In S507, the color conversion unit 213 generates a color conversion table for density emphasis. Since the color conversion table is a prior art, its explanation will be omitted.

In S508, the color conversion method setting unit 212 changes the setting of the color conversion method from "density emphasis" to "grayscaling for all colors" and "outline emphasis". When "contour enhancement" is set, the image processing control unit 204 is notified of an attribute data conversion instruction to convert the attribute data generated by the RIP 231 into attribute data for edge enhancement. Due to this change in the color conversion method, the color conversion unit 213 no longer generates a color conversion table for density emphasis.

In S509, the page analysis unit 203 generates intermediate data based on the drawing command. Specifically, drawing commands and registered characters (fonts) expressed in relative coordinates and Bezier curves are converted into path point sequences in absolute coordinates that match the actual output resolution and paper size.

In S510, the page analysis unit 203 determines whether to perform fallback processing because the intermediate data obtained while generating one page of intermediate data does not fit within the intermediate data storage area of the RAM 222. . If fallback processing is not to be performed, the generated intermediate data is sequentially stored in the RAM 222, the process returns to S503, and the next drawing command is read. If fallback processing is to be performed, the process moves to S511.

In S511, the color conversion unit 213 changes the setting of the color conversion method from "density emphasis" to "grayscaling for all colors" and "outline emphasis". Due to this change in the color conversion method, the color conversion unit 213 no longer generates a color conversion table for density emphasis. If "outline enhancement" is set, the image processing control unit 204 is notified to convert attribute data indicating the attribute of the object corresponding to each pixel of the raster image data into attribute data for edge enhancement. When performing fallback processing, record in the log that "density emphasis" has been canceled and changed to "grayscale for all colors" and "contour emphasis" and notify the user. It doesn't matter if it's configured.

In S512, the image processing control unit 204 obtains the attribute data conversion instruction, and renders the intermediate data stored in the RAM 222 in "grayscale conversion for all colors". The rendered raster image data is then registered as a background image in the intermediate data that could not be stored in the RAM 222. At this time, rendering of a portion of the intermediate data for one page stored in the RAM 222 was performed by calculating the color values of the used color table using a color conversion formula for "grayscaling for all colors". This is done based on gray values. Then, an area for storing the intermediate data is secured in the RAM 222, and the intermediate data in which the rendered raster image data that could not be stored in the RAM 222 is registered as a background image is sequentially stored in the RAM 222, and the process returns to S503 for the next step. Load the drawing instructions for. As a method for securing an area for storing intermediate data in the RAM 222, rendered intermediate data may be deleted or overwritten. This fallback process in S512 is performed as described in the flowchart shown in FIG. 4A, similar to S312 in the first embodiment.

In this way, as long as the color conversion method is "density emphasis" and the drawing command read in S503 is a command related to drawing within the page, the processes from S503 to S512 are repeated. Then, if the color conversion method is not "density emphasis" or if the drawing command read in S503 is not a command related to drawing within the page, the process moves to S513.

In S513, the page analysis unit 203 determines whether the drawing command read in S503 is a page break command. If it is a page break command, the process moves to S514; if it is not a page break command, the process moves to S515. do.

In S514, the page analysis unit 203 adds a job end command indicating the end of the page to the intermediate data, and notifies the image processing control unit 204 and the RIP 231 of one page's worth of intermediate data and the color conversion method.

In S515, the image processing control unit 204 generates raster image data based on the notified intermediate data for one page, and returns to S502. The details of S515 will be described later using the flowchart shown in FIG.

In S516, the page analysis unit 203 determines whether the drawing command read in S503 is a job end command. If it is a job end command, the process moves to S516; if it is not a job end command, the process moves to S509. Transition.

In S517, the page analysis unit 203 notifies the job analysis unit 202 that intermediate data conversion for all pages included in the print job has been completed, and ends this sequence.

FIG. 6 shows a flowchart illustrating raster image data generation processing performed by the image processing control unit 204, which has been notified of the intermediate data for one page and the color conversion method, using the RIP 231 and the image editing unit 232.

In S601, the image processing control unit 204 acquires the location of the intermediate data, the location of the color conversion table, and the color conversion method to be executed.

In S602, the image processing control unit 204 determines whether "density emphasis" is set as the color conversion method, and if "density emphasis" is set, the process moves to S603, and "density emphasis" is set. If it has not been set, the process moves to S603.

In S603, the image processing control unit 204 uses the color conversion unit 213 to convert the color values of the used color table of the intermediate data using the color conversion table for density emphasis of the color conversion result.

In S604, the image processing control unit 204 uses the color conversion unit 213 to convert the color values of the color table used in the intermediate data based on the color conversion formula for converting all colors to gray scale.

In step S605, the image processing control unit 204 converts the attribute data into attribute data for contour enhancement for determining boundaries between objects where the density value interval of a single color is equal to or less than a predetermined threshold, according to the attribute data conversion instruction. Convert to

In S606, the image processing control unit 204 generates raster image data that matches the output resolution and paper size based on the intermediate data and the color table converted into grayscale by the image processing control unit 204.

In S607, the image processing control unit 204 determines whether or not attribute data for edge enhancement is included. If attribute data for edge enhancement is included, the process proceeds to S608, and the image processing control unit 204 determines whether attribute data for edge enhancement is included. If attribute data is not included, this sequence ends.

In S608, the image processing control unit 204 uses the image editing unit 232 to emphasize the boundaries between pixel areas where the density value interval of a single color is equal to or less than a predetermined threshold based on the attribute data for edge enhancement. Execute contour enhancement processing on raster image data. The specific means for contour enhancement processing is the same as that of the prior art, so a description thereof will be omitted.

The above is the raster image data generation process of the image processing control unit 204 that has received notification of one page's worth of intermediate data and the color conversion method. These processes are executed by the RIP 231 and the image editing unit 232 on intermediate data generated by the page analysis unit 203 executed by the CPU 220. Therefore, the processing by the job analysis unit 202 and the page analysis unit 203 shown in FIG. 5 operates in parallel with the raster image data generation processing shown in FIG. 6.

As a result of these processes, when fallback processing is performed on a print job for which density emphasis is set as the color conversion method, the color conversion method is switched to grayscale conversion for all colors, and edge emphasis processing is performed. As a result, it is possible for the user to improve discrimination and prevent mismatching of drawn colors.

<Third embodiment>
A third embodiment for implementing the present invention will be described below with reference to the drawings. The third embodiment is a recovery process in which intermediate data is saved to the auxiliary storage device 223 without being rendered and processing is continued when fallback processing is performed for a print job in which density emphasis is set. Note that the configuration of the print control device of the third embodiment is similar to the configuration of the first embodiment shown in FIG. Below, points different from the first embodiment will be explained.

FIG. 7 shows that in a print job in which "density emphasis" is set as the color conversion method for monochrome printing in the third embodiment, intermediate data is stored in the auxiliary storage device 223 without being rendered when fallback processing is performed. A flowchart of the process of saving and continuing the process is shown.

In S701, the job analysis unit 202 reads a job start command from the input data acquired by the data input unit 201. Next, the job analysis unit 202 uses the color information acquisition unit 211 to read the color mode setting command. Only the processing when the print job requires conversion to gray data based on the result read by the color information acquisition unit 211 and when "density emphasis" is set as the color conversion method will be described. If the designation is other than that, the description is omitted because it is the same as the conventional technology.

In S702, the page analysis unit 203 reads a page start command. At this time, "density emphasis" is set as the color conversion method for the page. Further, the count of the number of colors in a page, which is necessary for density emphasis processing, is initialized to 0.

In S703, the page analysis unit 203 reads a drawing command.

In S704, if the color conversion method is "density emphasis" and the drawing command read in S703 is a command related to drawing within the page, such as a fill color specification command, the page analysis unit 203 determines the content of the command. is transmitted to the color conversion method setting unit 212, and the process moves to S705. If the color conversion method is not "density emphasis" or if the drawing command read in S703 is not a command related to drawing within the page, the process moves to S713.

In S705, the color conversion method setting unit 212 counts the number of colors used from the drawing command related to color specification read by the page analysis unit 203. Note that at this time, colors that have been counted once within the same page are not counted in the number of colors even if the same color appears thereafter.

In S706, the color conversion method setting unit 212 determines whether the number of colors used within the page exceeds a predetermined threshold. More specifically, in cases where the total number of colors exceeds the number of gradations of gray data that can be expressed by the printer unit 111, it is possible to convert color data into gray data with visible density differences. Determine whether If the number of colors used is less than or equal to the predetermined threshold, the process moves to S707, and if the number of colors used exceeds the predetermined threshold, the process moves to S708.

In S707, the color conversion unit 213 generates a color conversion table for density emphasis. Since the color conversion table is a prior art, its explanation will be omitted.

In S708, the color conversion method setting unit 212 changes the setting of the color conversion method from "density emphasis" to "grayscaling for all colors." Due to this change in the color conversion method, the color conversion unit 213 no longer generates a color conversion table for density emphasis.

In S709, the page analysis unit 203 generates intermediate data based on the drawing command. Specifically, drawing commands and registered characters (fonts) expressed in relative coordinates and Bezier curves are converted into path point sequences in absolute coordinates that match the actual output resolution and paper size.

In S710, the page analysis unit 203 determines whether to perform fallback processing because the intermediate data obtained while generating one page of intermediate data does not fit within the intermediate data storage area of the RAM 222. . If fallback processing is not to be performed, the generated intermediate data is sequentially stored in the RAM 222, the process returns to S703, and the next drawing command is read. If fallback processing is to be performed, the process moves to S711.

In S711, the page analysis unit 203 determines whether the intermediate data can be saved from the RAM 222 to the auxiliary storage device 223 and stored (spooled). If the intermediate data can be saved to the auxiliary storage device 223, the process moves to S712, and if it cannot be saved, the process moves to S713.

In S712, the page analysis unit 203 stores the intermediate data stored in the RAM 222 and the intermediate data that could not be stored in the RAM 222 in the auxiliary storage device 223, returns to S703, and reads the next drawing command.

In S713, the color conversion method setting unit 213 changes the setting of the color conversion method from "density emphasis" to "grayscaling for all colors." Due to this change in the color conversion method, the color conversion unit 213 no longer generates a color conversion table for density emphasis. If the intermediate data cannot be saved to the auxiliary storage device 223 and fallback processing is performed, it is possible to record in the log that "density emphasis" has been canceled and changed to "grayscale conversion for all colors" along with the fallback processing, and , the user may be notified.

In S714, the image processing control unit 204 executes a fallback process in which the intermediate data stored in the RAM 222 is rendered once, and the rendered raster image data is registered as a background image in the intermediate data that could not be stored in the RAM 222. do. At this time, rendering of a portion of the intermediate data for one page stored in the RAM 222 was performed by calculating the color values of the used color table using a color conversion formula for "grayscaling for all colors". This is done based on gray values. Then, an area for storing the intermediate data is secured in the RAM 222 or the auxiliary storage device 223, and the intermediate data in which the rendered raster image data that could not be stored in the RAM 222 is registered as a background image is stored in the RAM 222 or the auxiliary storage device. 223. After that, the process returns to S703 and reads the next drawing command. As a method for securing an area for storing intermediate data in the RAM 222, rendered intermediate data may be deleted or overwritten. This fallback process in S714 is performed as described in the flowchart shown in FIG. 4A, similar to S312 in the first embodiment.

In this way, as long as the color conversion method is "density emphasis" and the drawing command read in S703 is a command related to drawing within the page, the processes from S703 to S714 are repeated. If the color conversion method is not "density emphasis" or if the drawing command read in S703 is not a command related to drawing within the page, the process moves to S715.

In S715, the page analysis unit 203 determines whether the drawing command read in S703 is a page break command. If it is a page break command, the process moves to S716; if it is not a page break command, the process advances to S717. to move to.

In S716, the page analysis unit 203 adds a job end command indicating the end of the page to the intermediate data, and notifies the image processing control unit 204 and the RIP 231 of one page's worth of intermediate data and the color conversion method.

In S717, the image processing control unit 204 generates raster image data based on the notified intermediate data for one page, and returns to S702. The details of S717 will be described later using the flowchart shown in FIG.

In S718, the page analysis unit 203 determines whether the drawing command read in S703 is a job end command, and if it is a job end command, the process moves to S718, and if it is not a job end command, the process moves to S709. do.

In S719, the page analysis unit 203 notifies the job analysis unit 202 that intermediate data conversion for all pages included in the print job has been completed, and ends this sequence.

FIG. 8 shows a flowchart illustrating raster image data generation processing performed by the image processing control unit 204 using the RIP 231 after receiving one page of intermediate data stored in the RAM 222 or the auxiliary storage device 223 and notification of the color conversion method. show.

In S801, the image processing control unit 204 acquires the location of the intermediate data, the location of the color conversion table, and the color conversion method to be executed.

In S802, the image processing control unit 204 determines whether "density emphasis" is set as the color conversion method, and if "density emphasis" is set, the process moves to S803 and "density emphasis" is set. If not set, the process moves to S804.

In S803, the image processing control unit 204 uses the color conversion unit 213 to convert the color values of the used color table of the intermediate data using the color conversion table for density modulation of the color conversion result.

In S804, the image processing control unit 204 uses the color conversion unit 213 to convert the color values of the color table used in the intermediate data based on the color conversion formula for converting all colors to grayscale.

In S805, the image processing control unit 204 generates raster image data matching the output resolution and paper size based on the intermediate data and the grayscale color table.

The above is the raster image data generation process of the image processing control unit 204 that has been notified of one page's worth of intermediate data and color conversion method, and these processes are executed by the RIP 231 according to instructions from the page analysis unit 203 executed by the CPU 220. executed. Therefore, the job analysis and page analysis shown in FIG. 7 operate in parallel with the image forming process shown in FIG. 8.

As a result of these processes, when fallback processing is performed for a print job in which density emphasis is set as the color conversion method, intermediate data is saved to the storage device and processing continues. As a result, it is possible to improve discrimination by emphasizing density and prevent mismatching of drawn colors. Furthermore, if the data cannot be saved to the storage device, the density enhancement process can be canceled to prevent mismatching of drawn colors.

<Fourth embodiment>
Hereinafter, a fourth embodiment for implementing the present invention will be described using the drawings. In the fourth embodiment, for a print job in which density emphasis is set as the color conversion method, the generation of the color conversion table for density emphasis continues when fallback processing is performed, and the color conversion table for density emphasis is generated for raster image data instead of intermediate data. This is recovery processing that executes color conversion for density emphasis. Note that the configuration of the print control device of the fourth embodiment is similar to the configuration of the first embodiment shown in FIG. Below, points different from the first embodiment will be explained.

FIG. 9 shows that when fallback processing is performed in a print job in which density emphasis is set as the color conversion method for monochrome printing according to the fourth embodiment, generation of a color conversion table for density emphasis is continued, and the raster image is A flowchart illustrating a process of performing color conversion on data is shown.

In S901, the job analysis unit 202 reads a job start command from the input data acquired by the data input unit 201. Next, the job analysis unit 202 uses the color information acquisition unit 211 to read the color mode setting command. Only the processing when the print job requires conversion to gray data based on the result read by the color information acquisition unit 211 and when "density emphasis" is set as the color conversion method will be described. If the designation is other than that, the description is omitted because it is the same as the conventional technology.

In S902, the page analysis unit 203 reads a page start command. At this time, "density emphasis" is set as the color conversion method for the page. Further, the count of the number of colors in a page, which is necessary for density emphasis processing, is initialized to 0.

In S903, the page analysis unit 203 reads a drawing command.

In S904, if the color conversion method is "density emphasis" and the drawing command read in S903 is a command related to drawing within the page, such as a fill color specification command, the page analysis unit 203 determines the content of the command. The color conversion method setting unit 212 is informed, and the process moves to S905. If the color conversion method is not "density emphasis" or if the drawing command read in S903 is not a command related to drawing within the page, the process moves to S913.

In S905, the color conversion method setting unit 212 counts the number of colors used within the page from the drawing command related to color specification read by the page analysis unit 203. Note that at this time, for colors that have been counted once within the same page, the same color is not counted in the number of colors thereafter.

In S906, the color conversion method setting unit 212 determines whether the number of colors used within the page exceeds a predetermined threshold. More specifically, in cases where the total number of colors exceeds the number of gradations of gray data that can be expressed by the printer unit 111, it is determined whether the color data can be converted to gray data with a visible density difference. do. If the number of colors is less than or equal to the predetermined threshold, the process moves to S907, and if the number of colors exceeds the predetermined threshold, the process moves to S908. This means switching to a color conversion method that uses edge enhancement.

In S907, the color conversion unit 213 generates a color conversion table for density emphasis. Since the color conversion table is a prior art, its explanation will be omitted.

In S908, the color conversion method setting unit 212 changes the color conversion method from "density emphasis" to "grayscaling for all colors." Due to this change in the color conversion method, the color conversion unit 213 no longer generates a color conversion table for density emphasis.

In S909, the page analysis unit 203 generates intermediate data based on the drawing command. Specifically, drawing commands and registered characters (fonts) expressed in relative coordinates and Bezier curves are converted into path point sequences in absolute coordinates that match the actual output resolution and paper size.

In S910, the page analysis unit 203 determines whether to perform fallback processing because the intermediate data obtained while generating one page of intermediate data does not fit within the intermediate data storage area of the RAM 222. . If fallback processing is not performed, the converted intermediate data is sequentially stored in the RAM 222, the process returns to S903, and the next drawing command is read. If fallback processing is to be performed, the process moves to S911.

In S911, the image processing control unit 204 executes fallback processing to once render the intermediate data stored in the RAM 222 and register the rendered raster image data as a background image of the intermediate data that could not be stored in the RAM 222. do. At this time, rendering of a portion of intermediate data of one page of intermediate data stored in the RAM 222 is performed based on the used color table with the color values specified by the drawing command. Then, an area for storing the intermediate data is secured in the RAM 222, and the intermediate data in which the rendered raster image data that could not be stored in the RAM 222 is registered as a background image is sequentially stored in the RAM 222, and the process returns to S903 for the next step. Load the drawing instructions for. As a method for securing an area for storing intermediate data in the RAM 222, rendered intermediate data may be deleted or overwritten. This fallback process in S911 will be described later using the flowchart shown in FIG. 10(a).

In this way, while the color conversion method is "density emphasis" and the drawing command read in S703 is a command related to drawing within the page, the processes from S903 to S911 are repeated, and the color for density emphasis is Conversion table generation continues. If the color conversion method is not "density emphasis" or if the drawing command read in S903 is not a command related to drawing within the page, the process moves to S912.

In S912, the page analysis unit 203 determines whether the drawing command read in S903 is a page break command. If it is a page break command, the process moves to S913; if it is not a page break command, the process advances to S914. to move to.

In S913, the page analysis unit 203 adds a job end command indicating the end of the page to the intermediate data, and notifies the image processing control unit 204 and the RIP 231 of one page's worth of intermediate data and the color conversion method.

In S914, the image processing control unit 204 generates raster image data based on the notified intermediate data for one page, and returns to S902. The details of S914 will be described later using the flowchart shown in FIG.

In S915, the page analysis unit 203 determines whether the drawing command read in S903 is a job end command, and if it is a job end command, the process moves to S915, and if it is not a job end command, the process moves to S909. do.

In S916, the page analysis unit 203 notifies the job analysis unit 202 that intermediate data conversion for all pages included in the print job has been completed, and ends this sequence.

FIG. 10A shows a flowchart illustrating fallback processing by the image processing control unit 204 according to the fourth embodiment.

In S1011, the image processing control unit 204 acquires the storage location of the intermediate data and color conversion table, and the color conversion method to be executed.

In S1012, the image processing control unit 204 uses the RIP 231 to generate raster image data matching the output resolution and paper size based on the intermediate data and the color table for the color values specified in the drawing command.

In S1013, the image processing control unit 204 registers the raster image data generated in S1012 as a background image in the intermediate data that could not be stored in the RAM 222, and stores the raster image data in the RAM 222 instead of the generated intermediate data. .

FIG. 10B shows a flowchart illustrating raster image data generation processing performed by the image processing control unit 204 using the RIP 231 and the image editing unit 232 after receiving notification of the intermediate data for one page and the color conversion method.

In S1021, the image processing control unit 204 acquires the location of the intermediate data, the location of the color conversion table, and the color conversion method to be executed.

In step S1022, the image processing control unit 204 uses the RIP 231 to generate color raster image data matching the output resolution and paper size based on the intermediate data and the color table used.

In S1023, the image processing control unit 204 determines whether "density emphasis" is set as the color conversion method, and if "density emphasis" is set, the process moves to S1024, and "density emphasis" is set. If not, the process moves to S1025.

In S1024, the image processing control unit 204 uses the image editing unit 232 to compare the color values of the raster image data pixel by pixel using the color conversion table for density emphasis of the color conversion result, and Convert the color value of each pixel to a gray value.

In S1025, the image processing control unit 204 uses the image editing unit 232 to convert the pixel value of each pixel of the raster image data into a gray value based on a color conversion formula for converting all colors to gray scale.

The above is the raster image data generation process of the image processing control unit 204 that has been notified of the intermediate data and color conversion method for one page, and these processes are performed by the RIP 231 and the This is executed by the image editing section 232. Therefore, the job analysis and page analysis shown in FIG. 9 operate in parallel with the raster image data generation process shown in FIG. 10.

Through these processes, when fallback processing is performed for a print job in which density emphasis is set as the color conversion method, raster image data is generated from intermediate data without color conversion. Then, based on the continuously generated color conversion table for density emphasis, color conversion for density emphasis is performed on the generated raster image data. As a result, it is possible to improve discrimination by emphasizing density and prevent mismatching of drawn colors.

Note that in this embodiment, color conversion for raster image data is performed using the image editing unit 232; however, the color conversion unit 213 is provided with color conversion for raster image data, and is performed using the color conversion unit 213. It may also be a configuration.

(Other examples)
The present invention provides a system or device with a program that implements one or more of the functions of the embodiments described above via a network or a storage medium, and one or more processors in the computer of the system or device reads and executes the program. This can also be achieved by processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

203 Page analysis section 204 Image processing control section 212 Color conversion method setting section 213 Color conversion section

Claims (19)

An image processing device that generates raster image data for printing based on PDL data included in a print job for printing color data in monochrome,
an analysis unit that analyzes the PDL data to generate intermediate data for each drawing command, and sequentially stores the generated intermediate data in a storage device;
color conversion means for converting each density value of a plurality of colors represented by a plurality of color components specified in the PDL data into a single color density value using a color conversion method specified in the print job; ,
When the first color conversion method that improves discriminability is specified as the color conversion method in the print job, the analysis means uses intermediate data obtained while generating intermediate data for one page. a setting means for setting a second color conversion method different from the first color conversion method to the color conversion means when the color cannot be stored in the storage device;
image processing means for generating raster image data of the single color based on intermediate data stored in the storage device and a color conversion result by the color conversion means;
An image processing device comprising: The first color conversion method is a color conversion method that changes the density value of the single color corresponding to the density value of each of the plurality of colors according to the number of the plurality of colors,
The second color conversion method is a color conversion method that does not change the density value of the single color corresponding to the density value of each of the plurality of colors according to the number of the plurality of colors.
The image processing device according to claim 1, characterized in that: The first color conversion method converts the density value of each of the plurality of colors into the corresponding unit based on a color conversion table in which density value intervals of the single color are set according to the number of the plurality of colors. It is a color conversion method that converts to the density value of one color.
The image processing device according to claim 1 or 2, characterized in that: When the first color conversion method is specified and the number of the plurality of colors exceeds a predetermined threshold, the setting means causes the color conversion means to perform the first color conversion. canceling the method and setting a second color conversion method different from the first color conversion method;
The image processing apparatus according to any one of claims 1 to 3, characterized in that: If the analysis means is unable to store the intermediate data in the storage device,
The image processing means generates raster image data of the single color forming part of a page based on intermediate data stored in the storage device and a color conversion result by the color conversion means,
The analysis means registers raster image data forming a part of the page as a background image for the intermediate data that could not be stored in the storage device, and stores the raster image data in the storage device.
The image processing apparatus according to any one of claims 1 to 4. an edge enhancement unit that performs edge enhancement processing on the raster image data to emphasize boundaries between pixel areas where the density value interval of the single color is equal to or less than a predetermined threshold;
The image processing apparatus according to any one of claims 1 to 5, further comprising: an image processing apparatus according to claim 1; The image processing means generates attribute data in which a value indicating an attribute of the object is stored for a pixel corresponding to the object included in the one page of intermediate data,
The contour emphasizing means determines the boundary based on the attribute data,
The image processing apparatus according to claim 6, characterized in that: The analysis means generates a plurality of pieces of intermediate data that are less than one page of intermediate data that constitute the one page of intermediate data, and stores them in the storage device;
The image processing means generates raster image data based on the color conversion result by the color conversion means based on the plurality of intermediate data that is intermediate data for one page stored in the storage device.
The image processing device according to any one of claims 1 to 7. An image processing device that generates raster image data for printing based on PDL data included in a print job for printing color data in monochrome,
an analysis unit that analyzes the PDL data to generate intermediate data for each drawing command, and sequentially stores the generated intermediate data in a storage device;
color conversion means for converting each density value of a plurality of colors represented by a plurality of color components specified in the PDL data into a single color density value using a color conversion method specified in the print job; ,
image processing means for generating raster image data of the single color based on intermediate data stored in the storage device and a color conversion result by the color conversion means;
Equipped with
When the first color conversion method that improves discriminability is specified as the color conversion method in the print job, the analysis means uses intermediate data obtained while generating intermediate data for one page. If the image cannot be stored in the storage device, the image processing means generates raster image data including the plurality of colors based on the intermediate data stored in the storage device without using the color conversion result; The color conversion means converts the pixel value of each pixel of the raster image data including the plurality of colors using the first color conversion method.
An image processing device characterized by: The first color conversion method is a color conversion method that changes the density value of the single color corresponding to the density value of each of the plurality of colors according to the number of the plurality of colors.
The image processing device according to claim 9. The first color conversion method is a color conversion method that sets an interval between density values of the single color according to the number of the plurality of colors.
The image processing apparatus according to claim 9 or 10. If the analysis means is unable to store the intermediate data in the storage device,
The image processing means generates raster image data including the plurality of colors forming part of a page based on intermediate data stored in the storage device,
The analysis means registers raster image data forming a part of the page as a background image for the intermediate data that could not be stored in the storage device, and stores the raster image data in the storage device.
The image processing device according to any one of claims 9 to 11. When the first color conversion method is specified in the print job, if the number of the plurality of colors exceeds a predetermined threshold, the first color conversion method is specified for the color conversion means. setting means for canceling the color conversion method and setting a second color conversion method different from the first color conversion method;
The image processing device according to any one of claims 9 to 12, further comprising: The second color conversion method is a color conversion method that converts each density value of the plurality of colors into a corresponding density value of the single color based on the density value of each of the plurality of colors.
The image processing apparatus according to any one of claims 1 to 8 and 13. The first color conversion method converts the density value of each of the plurality of colors into the corresponding unit based on a color conversion table in which density value intervals of the single color are set according to the number of the plurality of colors. It is a color conversion method that converts to the density value of one color.
The image processing device according to any one of claims 1 to 14. An image processing device according to any one of claims 1 to 10,
image forming means for forming an image on a recording medium based on raster image data generated by the image processing device;
An image forming apparatus comprising: An image processing method for generating raster image data for printing based on PDL data included in a print job for printing color data in monochrome, the method comprising:
an analysis step of analyzing the PDL data to generate intermediate data for each drawing command, and sequentially storing the generated intermediate data in a storage device;
a color conversion step of converting each density value of a plurality of colors represented by a plurality of color components specified in the PDL data into a single color density value using a color conversion method specified in the print job; ,
When the first color conversion method that improves discriminability is specified as the color conversion method in the print job, the analysis step uses intermediate data obtained during generation of intermediate data for one page. a setting step of canceling the first color conversion method for the color conversion step and setting a second color conversion method different from the first color conversion method if the color conversion method cannot be stored in the storage device;
an image processing step of generating raster image data of the single color based on the intermediate data stored in the storage device and the color conversion result of the color conversion step;
An image processing method comprising: An image processing method for generating raster image data for printing based on PDL data included in a print job for printing color data in monochrome, the method comprising:
an analysis step of analyzing the PDL data to generate intermediate data for each drawing command, and sequentially storing the generated intermediate data in a storage device;
a color conversion step of converting each density value of a plurality of colors represented by a plurality of color components specified in the PDL data into a single color density value using a color conversion method specified in the print job; ,
an image processing step of generating raster image data of the single color based on the intermediate data stored in the storage device and the color conversion result of the color conversion step;
has
When the first color conversion method that improves discriminability is specified as the color conversion method in the print job, the analysis step uses intermediate data obtained during generation of intermediate data for one page. If the image cannot be stored in the storage device, in the image processing step, raster image data including the plurality of colors is generated without using the color conversion results, and one page of raster image data including the plurality of colors is generated. converting the pixel value of each pixel using the first color conversion method;
An image processing method characterized by: A program for causing a computer to function as the image processing device according to any one of claims 1 to 15.

Images