JP2011025478A - Image forming apparatus, image forming method, program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of efficiently reading or writing image plotting data, an image forming method, a program, and a recording medium. <P>SOLUTION: This image forming apparatus 110 includes a divide processing means 234 for dividing image plotting data in accordance with a size of an image data memory for storing the image plotting data, a count processing means 236 for counting the number of colors to be used in each pieces of the image plotting data divided by the divide processing means, an image plotting data storing means 238 for storing each pieces of the image plotting data divided by the divide processing means as intermediate data, a multi-value image plot processing means 240 for generating RGB format image plotting data by using the intermediate data, and a color conversion processing means 242 for converting the RGB format image plotting data generated by the multi-value image plot processing means into CMYK format image plotting data. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus, an image forming method, a program, and a recording medium that make drawing processing more efficient.

  When printing a document or image created on a computer, the image forming device analyzes and decodes data such as character and graphic position information and format information using PDL (Page Description Language) to create a bitmap image. And printing on a paper medium or the like. There is a transmission control process as a drawing process performed when the image forming apparatus analyzes and decodes the PDL. The transparency control process is a process for drawing an object drawn on the background so that the object is melted into the background, and is used in an OS such as Windows (registered trademark) Vista provided by Microsoft Corporation. Drawing processing based on XPS (XML Paper Specification) which is an electronic document standard.

  In the transparency control process, transparency attribute information of rendering data to be superimposed (hereinafter referred to as source data) and transparency attribute information of rendering destination image data (hereinafter referred to as a destination) on which source data is superimposed. Are used to determine color information of drawing data to be finally drawn. These pieces of transparency attribute information need to be stored for each pixel constituting the drawing data.

  Further, in the current image forming apparatus, a halftone process for expressing gradation in units of a plurality of pixels is performed on a color image obtained by analyzing PDL. Halftone processing is a technique for expressing a halftone (intermediate color) using only two colors of black and white, and is a technique for expressing a gray scale on a binary output display device. When the halftone process is executed, the attribute information of the drawing object is required even after the transparency control process.

  Therefore, when the transparency control process is executed, the color information, attribute information, and transparency attribute information of the drawing data are required for each pixel. In order to process the drawing data for one pixel with RGB 24 bits, the color information ( In addition to (3 bytes), it is necessary to load attribute information and transparent attribute information data into the CPU register.

  Japanese Patent Application Laid-Open No. 2004-133830 discloses a means for generating a drawing plane for drawing an input drawing command on a bitmap image, a means for generating a new drawing plane by superimposing an image object of the drawing command on the drawing plane, a drawing command, An image forming apparatus comprising: an information plane used to determine an attribute for each pixel of the entire image from the attribute. This image forming apparatus performs color space conversion from RGB 24-bit to CMYK 32-bit using an RGB 24-bit drawing plane and a 3-bit information plane. Therefore, the image forming apparatus of Patent Document 1 processes a data amount of at least 4 bytes in order to execute a drawing process for one pixel.

  On the other hand, the CPU used in the current image forming apparatus is usually configured to include a 32-bit (4-byte) register.

  When trying to execute the transparency control process in a conventional image forming apparatus as shown in Patent Document 1, it is necessary to load drawing data including transparency attribute information in addition to color information and attribute information, so that it is normally used. The 32-bit register cannot load drawing data for one pixel at a time. For this reason, the CPU must load the drawing data stored in the RAM or the like into the register in units of 1 byte to process the drawing data for one pixel, and the higher the resolution, the lower the drawing processing. There was a problem of becoming efficient.

  Therefore, there is a need for an image forming apparatus in which the CPU mounted on the image forming apparatus can efficiently read the drawing data with a small number of reading times and can further write the drawing data into the image data memory. .

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an image forming apparatus, an image forming method, a program, and a recording medium that can efficiently read and write drawing data. To do.

  In the present invention, in order to cope with the above-described problem, an image forming apparatus that processes drawing data includes a division processing unit that divides drawing data according to the size of an image data memory in which the drawing data is stored, and a division process. Counting processing means for counting the number of colors used in each drawing data divided by the means, drawing data storage means for saving each drawing data divided by the dividing processing means as intermediate data, and RGB format using the intermediate data Multi-value drawing processing means for generating the drawing data, and color conversion processing means for converting the drawing data in the RGB format generated by the multi-value drawing processing means into drawing data in the CMYK format.

  The intermediate data includes drawing data color information, drawing data attribute information, and a transparent attribute value indicating a ratio of drawing data transmission to the image data on which the drawing data is drawn. The means can execute the transparency control process on the drawing data using the color information and the transparency attribute value of the drawing data.

  Further, the multi-value drawing processing means can execute the transparency control process on the drawing data by using the color information and the transparency attribute value of the image data on which the drawing data is drawn.

  Further, the image forming apparatus includes a binary conversion processing unit that binarizes the drawing data by performing halftone processing on the drawing data generated by the color conversion processing unit using the attribute information of the drawing data. Furthermore, drawing data can be expressed in gray scale.

  Further, the CPU included in the image forming apparatus can read the drawing data for one pixel by reading twice, and the drawing processing can be made efficient.

  Furthermore, the color conversion processing means stores the drawing data in the CMYK format in the same area of the image data memory used when the multi-value drawing processing means generates the drawing data, thereby performing the writing process to the image data memory. Efficiency can be improved.

  Further, the counting processing unit creates an index table in which color values used in each divided drawing data and an index associated with the color value are registered, and the multi-value drawing processing unit stores the index table. Using the color value correspondence table in the RGB format and the CMYK format, the color conversion processing unit generates the RGB format rendering data in the CMYK format. Since it is converted into drawing data and used as output data, the amount of data required for the drawing process can be greatly reduced.

  Further, the attribute information of the drawing data includes information specifying an index drawing format that is a drawing format using an index table, and the multi-value drawing processing means uses information specifying the index drawing format. Any one of the 8-bit drawing format of RGB and the index drawing format can be selected as the drawing format.

  Further, the multi-value drawing processing means can designate an index drawing format according to the number of colors used in the divided drawing data.

  Furthermore, the multi-value drawing processing means can select a drawing format for each divided drawing data.

  Further, the multi-value drawing processing means executes the raster operation processing on the drawing data when the attribute information of the drawing data includes a value specifying the raster operation processing, and the transparent information is included in the attribute information of the drawing data. If the attribute value is included, the raster operation process or the transparency control process can be selectively designated in order to execute the transparency control process on the drawing data.

  Further, according to the present invention, the image forming apparatus divides drawing data according to the size of the image data memory, counts the number of colors used in each drawing data, stores each drawing data as intermediate data, Is used to generate drawing data in RGB format and convert the drawing data in RGB format into drawing data in CMYK format.

Furthermore, the present invention provides a computer-executable program and a recording medium for causing an image processing apparatus to function as the functional unit.

1 is a diagram illustrating an embodiment of a hardware configuration of an image forming apparatus 100 according to the present invention. The figure which showed the functional block 200 of the controller 110 of this embodiment. The flowchart of the drawing process which the controller 110 of this embodiment performs. The figure which showed embodiment of the drawing command 400B which the drawing command 400A of the conventional PDL and the controller 110 of this embodiment use. The figure which showed embodiment of the drawing object which the drawing module interface 232 drawn. The figure which showed embodiment of the color table and color number management table which are used in order that the count process part 236 counts the color of a drawing object. The figure which showed the data structure 700A and drawing command corresponding table 700B of the drawing data preserve | saved as intermediate data. The conceptual diagram which shows the data structure of the image data memory 800 in which drawing data are stored. 6 is a flowchart of processing for creating an index table used when drawing data is processed in an index drawing format. The figure which showed embodiment of the index table produced by the process of FIG. The figure which showed the data structure of the drawing data stored in the image data memory by the dot drawing format by the index drawing format.

  Hereinafter, although this invention is demonstrated with embodiment, this invention is not limited to embodiment mentioned later. FIG. 1 shows an embodiment of a hardware configuration of an image forming apparatus 100 of the present invention. The image forming apparatus 100 functions as a print processing apparatus such as a network printer or a line printer, and receives a controller 110 that controls the image forming apparatus 100, an engine 140 that prints an image on paper, and input from a user. Or a panel device 150 that displays the state of the image forming apparatus 100.

  The controller 110 includes a CPU 112 and a ROM 114. CPU 112 executes instructions of a program implemented by controller 110. The ROM 114 stores a program that operates on the controller 110. The controller 110 includes a RAM 116 and functions as an image data memory such as a page memory that provides a page space generated by the program, and a work memory necessary for the program to operate. Further, the controller 110 includes an NVRAM 118, and the NVRAM 118 stores print setting conditions of the image forming apparatus 100 and the like.

  The controller 110 includes a network interface (hereinafter referred to as a network I / F) 120 and an engine interface (hereinafter referred to as an engine I / F) 122. The network I / F 120 includes: The data exchange with the host PC 130 is performed via the network, and the engine I / F 122 performs print control for the engine 140. Further, the controller 110 includes a panel interface (hereinafter referred to as a panel I / F) 124 for controlling the panel device 150, and receives various inputs from the user and executes various processes. .

  Further, the image forming apparatus 100 is connected to the host PC 130 via a network, and receives a print instruction from the host PC 130 and performs print processing. The network can be configured to include a wireless network complying with a standard such as Ethernet (registered trademark) such as 1000Base-TX, an optical network, IEEE802.11, etc., and can be mutually connected by packet communication based on a frame or TCP / IP protocol. Communication takes place. The network can be configured as a narrow area network such as a LAN (Local Area Network).

  FIG. 2 is a diagram illustrating a functional block 200 of the controller 110 according to the present embodiment. The controller 110 includes a PDL parser 220 that performs PDL (Page Description Language) syntax analysis and a drawing core 230 that performs drawing processing. The PDL parser 220 performs syntax analysis of PDL included in the print data received from the host PC 130. The PDL parser 220 can analyze various page description languages such as Post Script, PDF, PCL, and XPS, and can perform drawing regardless of the type of PDL by calling the drawing core 230 to execute drawing processing. is there.

  The drawing core 230 includes a drawing module interface (hereinafter referred to as a drawing module I / F) 232, a division processing unit 234, a counting processing unit 236, and a drawing data storage unit 238. The drawing module I / F 232 is an interface that receives drawing data such as text, images, and vector graphics from the PDL parser 220, and drawing setting information such as color, brush, transmission attribute value that is transmission attribute information, and line shape. Interface functions that can set drawing data and drawing setting information are provided. The drawing core 230 generates drawing data from the PDL using the interface function. The interface function will be described in detail later.

  When the controller 110 cannot secure a memory that can store drawing data for one page, the dividing processing unit 234 divides the drawing data into a size that can be stored in an image data memory such as a page memory. Specifically, the division processing unit 234 divides a drawing object which is data drawn by the drawing module I / F 232 according to the band height. The band height is the width of an area obtained by dividing a destination, which is image data on which a drawing object is drawn, in the y-axis direction, and is determined by the amount of drawing data that can be stored in the image data memory. Note that the division processing of the division processing unit 234 will be described later in more detail.

  The count processing unit 236 counts the number of colors that is the number of colors constituting each drawing object divided by the division processing unit 234. The counting processing unit 236 registers the counted number of colors in the color number management table in association with the band. In addition, the counting processing unit 236 creates an index table to be described later when the counted number of colors is equal to or less than a threshold value. The threshold value may be a value smaller than the number of colors represented by 8 bits for each color of RGB, for example, 2, 4, 16, 128, 256, and the like. Therefore, an index format that represents rendering data using an index table is used in comparison with an 8-bit rendering format for each color of RGB that requires a 24-bit image data memory to represent 1-pixel rendering data. The amount of data in the image data memory can be greatly reduced.

  The drawing data storage unit 238 stores the drawing data divided by the division processing unit 234 as intermediate data in a memory such as a RAM or a main storage device such as an HDD. The details of the counting process of the counting processing unit 236, the index table creation process, and the intermediate data to be stored will be described later in more detail.

  Further, the drawing core 230 includes a multi-value drawing processing unit 240, a color conversion processing unit 242, and a binary conversion processing unit 244. The multi-value drawing processing unit 240 generates drawing data of an object to be drawn using drawing data stored as intermediate data and destination drawing data, and image data memory as RGB color data of 8 bits for each color. To store. Further, when the drawing format is an index format, the multi-value drawing processing unit 240 stores the drawing data in the image data memory using the index table created by the counting processing unit 236.

  The color conversion processing unit 242 performs color conversion processing on the drawing data stored in the image data memory by the multi-value drawing processing unit 240, and converts the drawing data in RGB format into CMYK format that matches the color characteristics of the device. It converts to drawing data and updates the image data memory. Further, when the drawing format is the index format, the color conversion processing unit 242 converts the drawing data from the RGB format to the CMYK format by using a correspondence table between the RBG format color values and the CMYK format color values.

  The binary conversion processing unit 244 receives drawing data and attribute data in the CMYK format from the image data memory, and uses the attribute data to perform gradation processing, dithering processing, etc. for each drawing object using a dither method or an error diffusion method. The halftone process is executed to convert the drawing data into a binary format. The attribute data includes flag information indicating the type of object, for example, whether each pixel constituting the object is an image, a character, a filled figure, a line, or the like. In the halftone process of this embodiment, the color of each pixel of the object is compared with the threshold value of the halftone pattern or dither pattern. If the color of the pixel is equal to or greater than the threshold value, the object type is determined from the attribute data. Judgment is performed, and halftone processing is performed using a halftone pattern suitable for the object.

  FIG. 3 shows a flowchart of the drawing process executed by the controller 110 of this embodiment. Hereinafter, the drawing process of the controller 110 will be described with reference to FIG.

  The process in FIG. 3 starts when the image forming apparatus 100 receives print data from the host PC 130. The processing in FIG. 3 starts from step S300. In step S301, the PDL parser 220 mounted on the controller 110 of the image forming apparatus 100 analyzes the page description language included in the received print data. In step S302, the PDL parser 220 calls the drawing module I / F 232 included in the drawing core 230 to execute the drawing process.

  In step S303, the division processing unit 234 divides the drawing object generated in step S302 for each specific band height. In step S304, the counting processing unit 236 counts the number of colors of each divided drawing object using a color table described later. In step S305, the counting processing unit 236 determines whether the number of colors counted in step S304 is equal to or smaller than the threshold value. If the number of colors is equal to or smaller than the threshold value (yes), the process branches to step S306. To do. In step S306, the count processing unit 236 creates an index table to be described later. On the other hand, if it is determined in step S305 that the number of colors is larger than the threshold value (no), the process branches to step S307.

  In step S307, the drawing data storage unit 238 stores the divided drawing data and drawing setting information as intermediate data. In step S308, the multi-value drawing processing unit 240 acquires intermediate data and determines whether the drawing format is an index format. If it is determined in step S308 that the drawing format is not the index format (no), the process branches to step S309. In step S309, the multilevel drawing processing unit 240 draws drawing data in the image data memory. In step S310, the color conversion processing unit 242 performs color conversion of drawing data in accordance with the color characteristics of the output device.

  On the other hand, if it is determined in step S308 that the drawing format is the index format (yes), the process branches to step S311. In step S311, the multilevel drawing processing unit 240 draws drawing data in the image data memory using the index table. In step S312, the color conversion processing unit 242 converts the drawing data from the RGB format to the CMYK format using the color value correspondence table in the RGB format and the CMYK format.

  In step S313, the binary conversion processing unit 244 performs halftone processing on the drawing data converted by the color conversion processing unit 242 to convert it into a binary format, and the process ends in step S314.

  FIG. 4 is a diagram showing an embodiment of a conventional PDL drawing command 400A and a drawing command 400B used by the controller 110 of this embodiment. The drawing command 400A is a drawing command used in Post Script. In the rendering command 400A, the RGB color space is designated as the color space, and the color value (0.5, 0.0, 0.0) is designated. The drawing command 400A draws a rectangle by designating diagonal coordinates (100, 100) and coordinates (200, 200).

  The drawing command 400B includes an interface function setcolor for specifying the color of drawing data and an interface function rectangle for drawing a rectangle. The interface function setcolor specifies a color space with a first argument, and specifies a color value of drawing data with a second to fourth argument in a range of 0.0 to 1.0. In the present embodiment, an RGB color space is designated as the color space, and a color value (0.5, 0.0, 0.0) is designated.

  The interface function “rectangle” is an interface function that draws a rectangle in which diagonal coordinates (100, 100) and coordinates (200, 200) are designated with a value to be rendered data as an argument. By calling these interface functions, it is possible to generate the same drawing data as the drawing data generated by the Post Script drawing command described above.

  FIG. 5 is a diagram showing an embodiment of a drawing object drawn by the drawing module I / F 232. Hereinafter, with reference to FIG. 5, the drawing data dividing process of the dividing processing unit 234 will be described.

  FIG. 5 shows drawing objects 510 and 520. In the embodiment of FIG. 5, the band height is set to 256, the Y coordinate is defined as 0 for band 0 to 255, and the Y coordinate is defined as band 1 for 256 to 512. The drawing object 510 is data drawn by setting an argument (100, 100, 200, 200) to the interface function “rectangle”. As shown in FIG. 5, the drawing object 510 is classified into the band 0 because the Y coordinate falls within the range of 0 to 255.

  The drawing object 520 is data drawn by setting an argument (100, 100, 300, 300) to the interface function “rectangle”. As shown in FIG. 5, the drawing object 520 exists across the boundary that defines the band height. Therefore, in the present embodiment, the division processing unit 234 divides the drawing object 520 into the drawing object 522 and the drawing object 524. In the present embodiment, the drawing object 522 is classified into band 0 and the drawing object 524 is classified into band 1. In the present embodiment, the band height is 256, but the band height can be arbitrarily set as long as it can be stored in the image data memory. In the present embodiment, the origin of coordinates is described with the lower left. However, in other embodiments, the origin can be defined as the upper left.

  The division processing unit 234 divides the drawing data into an amount of drawing data that can be stored in the image data memory, in this embodiment, drawing objects 510 and 520. Then, the multi-value drawing processing unit 240 stores one of the drawing data, for example, the drawing object 510 in the image data memory. Other drawing data, for example, the drawing object 520 is compressed and stored in a RAM other than the image data memory, or saved in the HDD. When the drawing process of the drawing data 510 is completed, the drawing data 510 is compressed and stored in a RAM other than the image data memory, or stored in the HDD. Then, the multi-value drawing processing unit 240 decompresses the compressed drawing data 520 and loads it into the image data memory, or loads drawing data from the HDD into the image data memory.

  FIG. 6 is a diagram illustrating an embodiment of a color table and a color number management table used by the counting processing unit 236 to count the colors of the drawing objects. Hereinafter, the color table 610 and the color number management table 620 will be described with reference to FIG. The color conversion processing according to the present embodiment is performed by various data described in FIG. 6 and processing performed on the various data.

  The color table 610 is a hash table, and is an array in which an index value 612 that is a hash value generated based on a color value indicating a color used in a drawing object is a subscript. The color table 610 of this embodiment has a data structure in which 256 arrays are combined, and each array stores color values indicating colors used in the drawing object in a list format.

  In the present embodiment, the index value 612 is calculated based on the color value of the color used in the drawing object. Specifically, when the color value of the pixel constituting the drawing object is RGB (255, 0, 0), the remainder (modulo) obtained by dividing the sum of these values by the hash table size is the hash value. And That is, in the case of RGB (255, 0, 0), the remainder (255) obtained by dividing the sum of color values (255 + 0 + 0) by the hash table size (256) is the hash value, that is, the index value. Accordingly, the color value (255, 0, 0) is stored in the array 616 associated with the index value (255).

  Similarly, when the color value is RGB (0, 0, 255), the remainder (255) obtained by dividing the sum (0 + 0 + 255) of the color value by the hash table size (256) is the index value, and the color The value (0, 0, 255) is added as a new list to the array 618 associated with the index value. If the same color value is already registered in the color table, the color value is not registered.

  The counting processing unit 236 creates a color table for each drawing object divided in band units, and counts the number of color values registered in the color table. Then, the counting processing unit 236 registers the counted number in the color number management table 620 as the number of colors used in the drawing object.

  The color number management table 620 is a data table for registering the number of colors used in each band. A band name that uniquely identifies the band generated by the division processing unit 234 is registered in the band 622 of the color number management table 620. In the number of colors 624, the number of colors used in each band is registered in association with the band name.

  FIG. 7 is a diagram illustrating a data structure 700A of drawing data stored as intermediate data by the drawing data storage unit 238 and a correspondence table 700B of drawing commands issued by the drawing module I / F 232. Hereinafter, the intermediate data will be described with reference to FIG.

  The intermediate data is data including attribute information, drawing position information, image data, and the like of each drawing object divided by the division processing unit 234, and is stored in a storage device such as a RAM or HDD in a FIFO (First In First Out) format. Is done. The intermediate data includes a record 710 in which a graphics state (GStatus) that is attribute information of a drawing object is stored, an ID number 722 of a drawing command issued by the drawing module I / F 232, a padding byte 724, and attribute information of the drawing command. A record 720 in which (flag) 726 is stored and a record 730 in which position information of drawing data generated by the drawing command is stored are included.

  The graphics state stored in the record 710 includes the color space, color value, transparency attribute value, raster operation (Raster Operation value (hereinafter referred to as ROP value)), line width, and drawing format information of the drawing object. Attribute information is included.The drawing format information is information for selecting whether to draw a drawing object in the RGB format or to draw in the index format.

  In the case of the drawing command setcolor (RGBColor, 0.5, 0.0, 0.0) described with reference to FIG. 5, the RGB color space and the color value (0.5, 0.0, 0.0) are Set as graphics state. When a plurality of colors are used in the same band, a plurality of color values can be set as the graphics state.

  A drawing command type issued by the drawing module I / F 232 is set in the drawing command ID number 722 included in the record 720. The correspondence table 700B shows the correspondence between the ID number of the drawing command and the drawing command. In this embodiment, ID = 0x00 indicates Rectangle, which is a command for drawing a rectangle, and ID = 0x01 indicates LineDraw, which is a command for drawing a straight line. ID = 0x02 indicates LineFill which is a command for painting an area surrounded by a straight line, and ID = 0x03 indicates Image which is a command for drawing an image. Further, ID = 0x04 indicates Text that is a command for drawing a character.

  The drawing command attribute information (flag) 726 includes, for example, information indicating that clipping is effective when the drawing command Rectangle is set to Clip, and the attribute information can be designated by bit operation.

  The record 730 stores the position information of the drawing object generated by the drawing command. In the case of the drawing command Rectangle (100, 100, 200, 200) described with reference to FIG. 5, the drawing object specified as an argument is stored. Lower left coordinates (100, 100) and upper right coordinates (200, 200) are registered in record 732, record 734, record 736 and record 738, respectively.

  In the record 740, drawing data of another band is registered as intermediate data. The drawing command ID 742 of the drawing data is set with a command for drawing text, and the drawing position of the text is designated by a record 744 and a record 746. In the record 748, a character code of a text such as EUC-JP, Shift_JIS, UTF-8 or the like is registered. In the record 750, the size of a character to be drawn is registered, and a value such as a point specifying the size of the character is set.

  Further, in the record 760, drawing data of other bands are registered as intermediate data. A drawing command ID 762 of the drawing data is set with a command for drawing an image, and the drawing position of the image is designated by a record 764 and a record 766. In the record 768, image data to be drawn is set. The record 768 can store an address of a memory area where image data to be drawn is stored, compressed image data, uncompressed image data, and the like.

  In the present embodiment, the drawing position of the drawing object is described on the assumption that the origin of the coordinates is located at the lower left. However, in other embodiments, the drawing position is specified by defining the origin at the upper left. be able to.

  FIG. 8 is a conceptual diagram showing the data structure of the image data memory 800 in which drawing data is stored. An image data memory 800 shown in FIG. 8 includes an RGB plane 810 that is a memory area in which RGB color information of each pixel is stored in a dot sequential format, and an attribute plane 820 that is a memory area in which attribute values of each pixel are stored. , And a transmission plane 830 which is a memory area in which the transmission attribute value of each pixel of the destination is stored.

  The RGB plane 810 is a memory area in which color information (P, R, G, B) for each pixel of the object subjected to the drawing process is set, and each pixel constituting the destination where the drawing object is drawn is set. Color information is preset. In the RGB plane 810, for example, when nothing is drawn on the page, Cd (P, R, G, B) = (0, 255, 255, 255) which is the destination color value as an initial value Is set. In the RGB plane 810, Cd ′, which is the color value of the destination after the drawing process calculated using the color value of the destination or the like, is registered. The method for calculating the destination color value Cd ′ will be described in more detail later.

  Since each color information of the RGB plane 810 has a data amount of 1 byte, the data size of the color information necessary for rendering one pixel is 4 bytes. P is a padding byte. When the color space is an RGB color space, 0 is filled as the padding byte. R, G, and B represent red, green, and blue, respectively. In this embodiment, since each color has an 8-bit information amount, each color can represent 256 types of colors.

  The attribute plane 820 is a memory area in which attribute information of each pixel of the object subjected to the drawing process is stored. The attribute information is information for distinguishing the type of the drawn pixel, and is used for distinguishing whether the drawn pixel is a character, an image, graphics, or the like. In the present embodiment, the size of attribute information necessary for rendering one pixel is 1 byte (8 bits), and up to 256 types of attribute information can be provided per pixel.

  The transparency plane 830 is a memory area in which the transparency attribute value of the object subjected to the transparency control process is registered, and the transparency attribute value of each pixel constituting the destination where the drawing object is rendered is set in advance. In the transmission plane 830, for example, the destination transmission attribute value Ad = 0 (non-transmission) is set as an initial value. The transmission attribute value is a value indicating the transmission ratio of the drawing data to be superimposed, and is specified by a value of 0 to 100. The transparency attribute value is used to determine the color value of the destination after the drawing process, and Ad ′ that is the transparency attribute value of the destination after the transparency control process is registered in the transparency plane 830. A method for calculating the destination transmission attribute value Ad ′ after the transmission control process will be described later in more detail. In the present embodiment, the data size of the transparency attribute value required for drawing one pixel is 1 byte (8 bits). Note that the transparent plane 830 is not used when the raster operation process is executed.

  The CPU 112 of the image forming apparatus 100 according to the present embodiment processes 4-byte color information, 1-byte attribute information, and 1-byte transparency attribute information as rendering data for one pixel, and is necessary for rendering processing for one pixel. The total drawing data size is 6 bytes in total. In the present embodiment, when a 1-pixel rendering process is executed, the 32-bit register included in the CPU 112 loads 4-byte color information, 1-byte attribute information, and 1-byte transparency attribute information individually. The drawing data for one pixel can be acquired by a total of two reading processes.

  In this embodiment, the attribute plane 820 and the transmission plane 830 are described as separate memory areas. However, in other embodiments, the attribute information and the transmission attribute value of the same pixel are stored in the same plane. May be. In this case, a 2-byte memory area is required as attribute information and transparency attribute value for one pixel.

  The multi-value drawing processing unit 240 sequentially extracts drawing data stored as intermediate data in the FIFO format, executes raster operation processing or transparency control processing, and stores them in the image data memory as shown in FIG. The raster operation process is an image process performed by a graphics engine used in a Windows (registered trademark) OS, and performs a bit operation (for example, OR, etc.) on the color value of each pixel constituting a figure to be superimposed in the same area. XOR, AND, etc.).

  The transparency control process is an image process used in XPS or PDF supported by an OS such as Windows (registered trademark) Vista, and uses a transparency attribute value (0 to 100%) of a figure to be superimposed in the same area. This is a process for determining the color value and realizing the transparent drawing of the drawing object. The multi-value drawing processing unit 240 of this embodiment does not perform drawing processing using both raster operation processing and transparency control processing, but in other embodiments, both raster operation processing and transparency control processing are performed simultaneously. May be used to perform the drawing process.

  Hereinafter, the above-described transmission control process of the present embodiment will be described in more detail. Usually, the transparency control process is executed only for the source data to be rendered (1) and (2) performed for both the source data and the destination where the source data is rendered. is there.

  In the case of (1), when the pixel value of the source data is S, the pixel value of the destination is D, and the transparency attribute value of the source data is α (value of 0 to 1), the color value NewD after execution of the transparency control process is It becomes as follows.

  This process is performed for each color of RGB. If the destination pixel value D does not exist, the transmissive plane 830 is not used.

  In the case of (2), the transparent attribute value of the source data is As (value of 0 to 1), the transparent attribute value of the destination is Ad, the transparent attribute value of the destination after performing the transparent control process is Ad ′, and the source data When the color value is Cs, the destination color value is Cd, and the destination color value after the transmission control processing is Cd ′, the following expression is established.

  The transmission attribute value Ad ′ of the destination calculated by the transmission control process is stored in the corresponding memory area of the transmission plane 830.

  When performing the drawing process, the multilevel drawing processing unit 240 acquires a graphics state (GStatus) stored as intermediate data. When the transparency attribute value of the object to be rendered is set in GStatus, the multi-value rendering processor 240 acquires the transparency attribute value and the color value from GStatus and is set in the RGB plane 810. The destination color value and the transmission attribute value of the destination set in the transmission plane 830 are acquired.

  Then, the multi-value rendering processing unit 240 executes the transparency control process using the transparency attribute value and color value of the rendering object and the color value and transparency attribute value of the destination, and creates a new rendering data destination. The color value and transmission attribute value of the nation are calculated, and the image data memory is updated. In the present embodiment, a single transparency control processing method is adopted when processing the same page, and therefore, a plurality of methods are not mixed.

  On the other hand, when an ID for specifying raster operation processing is set as the ROP value in GStatus, the multi-value rendering processing unit 240 applies the color value of each pixel of the source data and destination data to be superimposed to each other. The bit operation specified by the ID is executed. The ID can be set in 256 ways from 0 to 255, and a bit operation is associated with each ID in advance.

  Next, the color conversion processing unit 242 executes color conversion processing on the drawing data generated by the multi-value drawing processing unit 240. The color conversion process is a process of converting the color information of the drawing data from the RGB format to the CMYK format. In this embodiment, the color conversion process includes a color matching process and a BG / UCR (Black generation / Under Color removal) process. Used.

  The color conversion processing unit 242 acquires RGB-format drawing data stored in the RGB plane 810 and the attribute plane 820 generated by the multi-value drawing processing unit 240 from the image data memory, and calls the color matching module. The color matching module performs a color matching process on the acquired drawing data, converts the color of the drawing data into a color suitable for the color characteristics of the output device, and stores it in the same address of the image data memory.

  Further, in the color matching process, the color can be converted for each type of drawing object such as a character, an image, or a graphic with reference to the attribute data stored in the attribute plane.

  Next, the color conversion processing unit 242 calls the BG / UCR module. The BG / UCR module performs BG / UCR processing on the drawing data stored in the image data memory, and converts the drawing data representation format from the RGB format to the CMYK format.

  FIG. 8 shows a KCMY plane 840 that is a memory area in which drawing data in the CMYK format after the BG / UCR process is performed. The KCMY plane 840 includes color information (K, C, M, Y) for each pixel. Each color information has a data amount of 1 byte, and the data size of the color information necessary for rendering one pixel is 4 bytes. K, C, M, and Y represent black, cyan, magenta, and yellow, respectively. In this embodiment, each color has an 8-bit information amount, and thus each color can represent 256 types of colors. .

  As shown in FIG. 8, the size of the drawing data is not changed before and after the BG / UCR process, and in this embodiment, the size of the drawing data remains 4 bytes. Further, the drawing data after the BG / UCR process is stored in the same area of the image data memory. That is, the color conversion processing unit 242 can execute the color conversion process without acquiring an extra memory area.

  Next, the binary conversion processing unit 244 acquires drawing data and attribute data in the CMYK format generated by the color conversion processing unit 242 from the image data memory, and executes halftone processing.

  FIG. 9 is a flowchart of an index table creation process used when the multi-value drawing processing unit 240 of this embodiment processes drawing data in the index drawing format. The index drawing format is a drawing format using an index table, and requires a smaller amount of data to express one pixel of drawing data than a drawing format in which drawing processing is performed with 8 bits for each RGB color. Hereinafter, the index table creation process will be described with reference to FIG. In the present embodiment, the count processing unit 236 creates the index table. However, in other embodiments, other function processing units may create the index table.

  The process of FIG. 9 corresponds to step S306 of the process described with reference to FIG. The process of FIG. 9 starts from step S900, and is initialized by setting 0 to a variable Index for setting an index value in step S901. In step S902, the count processing unit 236 acquires attribute information (GStatus) of the corresponding band. In step S903, the count processing unit 236 uses the color value of the color used in the band included in the acquired attribute information. Is registered in the index table. In step S904, the count processing unit 236 registers the value of the variable Index as an index value in the index table in association with the color value registered in step S903.

  In step S905, the counting processing unit 236 determines whether all the color values used in the corresponding band are registered. If all the color values are not registered (no), the processing is performed. Branches to step S906. In step S906, the value of the variable Index is incremented, and the process returns to step S903.

  On the other hand, if it is determined in step S905 that all color values are registered (yes), the process branches to step S907. In step S907, the count processing unit 236 determines whether there is other band attribute information to be acquired. If there is band attribute information to be acquired (yes), the process returns to step S901. Create another band index table.

  On the other hand, if it is determined in step S907 that there is no band attribute information to be acquired (no), the process branches to step S908, and the process of FIG. 9 ends.

  FIG. 10 is a diagram showing an embodiment of an index table created by the process of FIG. Hereinafter, the index tables 1010 and 1020 will be described with reference to FIG. The index table is created for each band generated by the division processing unit 234. The index table 1010 is an index table for a certain band, and the index table 1020 is an index table for another band.

  In the index tables 1010 and 1020, color values 1014 and 1024 of colors used in the band and indexes 1012 and 1022 associated with the colors are registered. In this embodiment, (255, 0, 0) and (0, 0, 255) are registered as color values in the index table 1010, and 0 and 1 are registered in association with each other as index values. . In the index table 1020, (255, 0, 0), (0, 0, 255), (0, 255, 0) and (0, 255, 255) are registered as color values. Values 0, 1, 2, and 3 are associated and registered. In the present embodiment, the color value is expressed in RGB format, and the index value is expressed in decimal.

  FIG. 11 is a diagram showing a data structure of drawing data stored in the image data memories 1110, 1120 and 1130 in the dot sequential format according to the index drawing format. The image data memory 1110 is an embodiment that expresses the color value of one pixel constituting the drawing data by 1 bit, and can express a maximum of two colors. The image data memory 1120 is an embodiment that expresses a color value of one pixel by 2 bits, and can express a maximum of four colors. The image data memory 1130 is an embodiment that expresses the color value of one pixel by 4 bits, and can express a maximum of 16 colors. For this reason, the index drawing format can reduce the amount of data required to represent 1-pixel drawing data, compared to a drawing format in which drawing processing is performed with 8 bits for each RGB color.

  The drawing core 230 according to the present embodiment acquires drawing data stored as intermediate data, and stores the drawing data in the image data memory using the index table when the index format is designated as the drawing format. . Then, the drawing core 230 converts the drawing data stored in the image data memory from the RGB format to the CMYK format by using a correspondence table of RGB color values and CMYK format color values prepared in advance. Can be output data.

  The above functions of the present embodiment can be realized by a device executable program described in an object-oriented programming language such as C, C ++, C #, Java (registered trademark), etc. It can be stored and distributed in a device-readable recording medium such as a CD-ROM, MO, DVD, flexible disk, EEPROM, EPROM, etc., and can be transmitted via a network in a format that other devices can.

  Although the present embodiment has been described so far, the present invention is not limited to the above-described embodiment, and other embodiments, additions, changes, deletions, and the like can be conceived by those skilled in the art. It can be changed, and any aspect is within the scope of the present invention as long as the effects and effects of the present invention are exhibited.

DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus, 110 ... Controller, 112 ... CPU, 114 ... ROM, 116 ... RAM, 118 ... NVRAM, 120 ... Network I / F, 122 ... Engine I / F, 124 ... Panel I / F, 130 ... Host PC, 140 ... engine, 150 ... panel device, 220 ... PDL parser, 230 ... drawing core, 232 ... drawing module I / F, 234 ... division processing unit, 236 ... counting processing unit, 238 ... drawing data storage unit, 240 ... Multi-level drawing processing unit, 242... Color conversion processing unit, 244.

Japanese Patent Laid-Open No. 2004-24369

Claims (20)

An image forming apparatus for processing drawing data,
Division processing means for dividing the drawing data according to the size of the image data memory in which the drawing data is stored;
Counting processing means for counting the number of colors used in each drawing data divided by the dividing processing means;
Drawing data storage means for storing each drawing data divided by the division processing means as intermediate data;
Multi-value drawing processing means for generating drawing data in RGB format using the intermediate data;
Color conversion processing means for converting drawing data in RGB format generated by the multi-value drawing processing means into drawing data in CMYK format;
An image forming apparatus including: The intermediate data includes color information of the drawing data, attribute information of the drawing data, and a transmission attribute value indicating a transmission ratio of the drawing data with respect to image data on which the drawing data is drawn. ,
The image forming apparatus according to claim 1, wherein the multi-value drawing processing unit executes a transmission control process on the drawing data using color information of the drawing data and the transmission attribute value.   3. The image formation according to claim 2, wherein the multi-value rendering processing unit performs a transparency control process on the rendering data using color information and a transparency attribute value of image data on which the rendering data is rendered. apparatus.   The image forming apparatus further includes binary conversion processing means for performing halftone processing on the drawing data generated by the color conversion processing means using the attribute information of the drawing data to binarize the drawing data. The image forming apparatus according to claim 1, which is provided.   The image forming apparatus according to claim 1, wherein a CPU included in the image forming apparatus is capable of reading the drawing data for one pixel by two readings.   The color conversion processing means stores the drawing data in the CMYK format in the same area of an image data memory used when the multi-value drawing processing means generates drawing data. The image forming apparatus described in 1. The counting processing means creates an index table in which color values used in each divided drawing data and an index associated with the color values are registered,
The multi-value drawing processing means generates drawing data in RGB format using the index table,
The color conversion processing means converts the RGB drawing data generated by the multi-value drawing processing means into CMYK drawing data using the RGB and CMYK format color value correspondence table as output data. The image forming apparatus according to claim 1. The attribute information of the drawing data includes information for specifying an index drawing format that is a drawing format using the index table,
8. The multi-value rendering processing means can select one of RGB 8-bit rendering format and index rendering format as a rendering format using information specifying the index rendering format. Image forming apparatus.   The image forming apparatus according to claim 8, wherein the multi-value drawing processing unit can designate the index drawing format according to the number of colors used in the divided drawing data.   The image forming apparatus according to claim 8, wherein the multi-level drawing processing unit can select a drawing format for each divided drawing data.   The multi-value drawing processing means executes a raster operation process on the drawing data when the attribute information of the drawing data includes a value specifying a raster operation process, and the attribute information of the drawing data The image forming apparatus according to claim 2, wherein when the transparency attribute value is included, a transparency control process is performed on the rendering data to perform a rendering process. An image forming apparatus that processes drawing data, wherein the image forming apparatus includes:
Dividing the drawing data according to a size of an image data memory in which the drawing data is stored;
Counting the number of colors used in each divided drawing data;
Storing each of the divided drawing data as intermediate data;
Generating drawing data in RGB format using the intermediate data;
Converting the drawing data in the RGB format into drawing data in the CMYK format;
How to run. The intermediate data includes color information of the drawing data, attribute information of the drawing data, and a transmission attribute value indicating a transmission ratio of the drawing data with respect to image data on which the drawing data is drawn. In the method, the image forming apparatus includes:
The method according to claim 12, comprising performing a transparency control process on the drawing data using color information of the drawing data and the transparency attribute value.   The step of generating drawing data in the RGB format includes a step of executing a transparency control process on the drawing data using color information and a transparency attribute value of image data on which the drawing data is drawn. Item 14. The method according to Item 13.   The method further includes the step of the image forming apparatus binarizing the drawing data by performing halftone processing on the drawing data in the CMYK format using attribute information of the drawing data. The method according to any one of 12 to 14.   The method according to any one of claims 12 to 15, wherein a CPU provided in the image forming apparatus can read the drawing data for one pixel by two readings.   The conversion step includes a step of storing the drawing data in the CMYK format in the same area of the image data memory used when the drawing data in the RGB format is generated. The method described. The counting step includes a step of creating an index table in which color values used in each of the divided drawing data and an index associated with the color value are registered,
The step of generating the drawing data in the RGB format includes the step of generating drawing data in the RGB format using the index table,
The converting step includes a step of converting the drawing data in the RGB format into drawing data in the CMYK format using the color value correspondence table in the RGB format and the CMYK format as output data. The method of any one of these.   A computer-executable program for causing an image forming apparatus to execute each step according to any one of claims 12 to 18.   A computer-readable recording medium on which the computer-executable program according to claim 19 is recorded.