JP2011020276A - Image forming apparatus, image data processing method, and control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an access efficiency to pixel data conserved through a multiple value drawing processing for intermediate data of PDL in which a translucent drawing processing has been established. <P>SOLUTION: A color plane which shows a color value as the pixel data of point sequential by the multiple value drawing processing based on the intermediate data of PDL is drawn using a lookup table (1 byte). When drawing a plane (1 byte) showing a pixel attribute and a destination transmission plane (1 byte) showing a translucent value for the translucent drawing processing, an integrated plane is drawn in which both planes of the pixel attribute and the destination transmission are summarized and conserved with 2 bytes per one pixel. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus (for example, a printer, a digital copying machine, a multifunction peripheral, etc.) having means for processing input data expressed in a page description language (PDL) into print output data. The present invention relates to an image forming apparatus having processing means for improving access efficiency to intermediate (pixel) data of PDL for which translucent rendering processing is set, an image data processing method used in the image forming apparatus, and a control program.

  2. Description of the Related Art Conventionally, an image forming apparatus such as a printer receives a print command expressed by a page description language (PDL) created by a host device, processes it as print output data, and uses it for output. As the PDL, PostScript, PDF (Portable Document Format), PCL (Printer Control Language), XPS (XML (Extensible Markup Language) Paper Description, etc. are used. It is equipped with a parser for analyzing each.

In XPS, which is one of the PDLs, a process that does not exist in the conventional PDL called semi-transparent rendering is newly added. The translucent drawing process is a process of superimposing images with each other in a translucent manner, and is processed according to a set processing parameter (translucent value). Specifically, the semi-transparency value of each image to be superimposed is set to 1 or less, and this processing parameter is usually set for each drawing object so that the whole becomes 1 when superimposed.
This translucent rendering process is a process performed on RGB 24-bit multivalued pixel data based on intermediate data obtained after PDL analysis. That is, in order to obtain print output data, it is necessary to perform image processing (halftone processing, BG / UCR, etc.) and the like for each drawing object in units of pixels. However, the translucent rendering process is also performed on RGB 24-bit multi-value rendering data in the same manner as these processes.

  By the way, the object information set in the PDL is not connected to each pixel after multi-value rendering of RGB 24 bits based on the intermediate data, so that it is used for subsequent image processing. It is necessary to save the object information described in the intermediate data. In other words, when drawing, object information is stored whether it is drawn with characters for each pixel, drawn with graphics, drawn with images, etc., and used in subsequent color processing and halftone processing There is a need to. A method of storing object information written in intermediate data for use in image processing in the form of an information plane used for attribute determination for each pixel is conventionally known (for example, Patent Document 1, reference).

The above-described semi-transparent drawing process parameter (semi-transparent value) must also be stored for each pixel as one piece of object information. Further, in the translucent rendering process of XPS, depending on the processing method of the translucent rendering process, it is necessary to store the translucent value of the rendering destination translucent rendering process. In this case, the drawing is performed using the translucent value of the data to be overlapped (referred to as “source data”) and the translucent value of the drawing destination (referred to as “destination”) (described in the following [Description of the Invention], This also needs to be saved for each pixel.
Accordingly, the information necessary for RGB 24-bit multi-value rendering requires pixel attributes and translucent values for each pixel in addition to color values. Therefore, when processing in RGB full color, in addition to RGB 24 bits per pixel, 1 byte is added for each pixel attribute and translucent value, and processing is performed while handling a total of 5 bytes of data. It will be.

  As described above, when multi-valued rendering processing is performed with RGB full color for PDL intermediate (pixel) data for which translucent rendering processing has been set, 5 bytes are required per pixel, so the pixels are arranged in order. Then, one pixel is accessed in units of 5 bytes. Since a CPU (Central Processing Unit) of a computer is usually configured with a register of 4 bytes (32 bits) at present, it cannot access one pixel (5 bytes of data) by one reading. Normally, one byte is accessed, so that one pixel data can be read with five instructions. Further, even in a CPU constituted by a 64-bit register, when 5 bytes are accessed, there is a case where the boundary always crosses the boundary, so the inefficiency is the same.

To solve this problem, a plane is provided for each of the color data, attribute data, and translucent rendering process data, and the data per pixel in the color plane is 4 bytes. The attribute plane and the translucent rendering process plane A method has been proposed in which the data per pixel is 1 byte, so that the total is 6 bytes per pixel. In this case, in the CPU having the 4-byte register configuration described above, data for just two pixels is read out in three accesses, and the memory access efficiency can be improved.
However, in order to improve the speed of image formation output in the image forming apparatus, further improvement in the memory access efficiency is required.
The present invention has been made in view of the above-described problems of the prior art, and its object is to improve the access efficiency to pixel data stored through multi-level drawing processing for intermediate data of PDL for which semi-transparent drawing processing is set. It is to improve.

According to one aspect of the present invention, a drawing command acquisition unit that acquires a drawing command obtained based on a page description language, and graphic information in which information is collected for each graphic to be drawn is based on the acquired drawing command. A graphic information generation unit to generate, a pixel information generation unit to generate pixel information that is information of pixels constituting the graphic based on the generated graphic information, and the pixel information by converting the generated pixel information Formation including a gradation information generation unit that generates gradation information for rendering the image, and an output information generation unit that generates output information for executing image formation output based on the generated gradation information The graphic information generation unit generates the graphic information including information related to translucent drawing of the graphic based on the drawing command, and the pixel information generation unit colors the pixels constituting the graphic. information, Index information indicating the color of the pixel as the color information of the pixel, storing the attribute information of the pixel and the information related to the translucent drawing of the figure formed by the pixel in a storage area reserved for the respective information The pixel information is generated by storing the color reference information, and the color reference information in which the index information and the information indicating the color of the pixel itself are associated is held in another storage area.
Further, it is preferable that the pixel information generation unit can store information indicating the color of the pixel itself as the color information of the pixel.
The pixel information generation unit preferably stores information indicating the color of the pixel itself as the color information of the pixel when the graphic to be drawn in the graphic information is full color data.
The pixel information generation unit preferably stores information indicating the color of the pixel itself as the color information of the pixel when the number of the index information included in the color reference information reaches a predetermined number. .
Further, the pixel information generation unit, as the color information of the pixel, when the graphic to be drawn in the graphic information is an index image, and the number of bits of an index for identifying the index image is a predetermined number or more It is preferable to store information indicating the coloring of the pixel itself.
It is preferable that the number of index information that can be registered in the color reference information is variable.
In addition, the pixel information generation unit generates the pixel information based on the graphic information for each band that is each range obtained by dividing the page into a plurality of bits, and the number of bits of information indicating the coloring of the pixel itself is different. It is preferable that the number of bits can be used for each band.
In the chromatic reference information, it is preferable that different numbers of bits can be mixed as the number of bits of information indicating the chromatic color of the pixel itself.
Another aspect of the present invention is an image data processing method, wherein a drawing command acquisition unit acquires a drawing command obtained based on a page description language, and a graphic information generation unit provides information for each graphic to be drawn. Is generated based on the acquired drawing command, and the pixel information generation unit generates the graphic information based on the generated graphic information. The information about the coloring of the pixels constituting the pixel, the attribute information of the pixels, and the information related to the translucent drawing of the figure constituted by the pixels are stored in a storage area reserved for each information, and as the coloring information of the pixels By storing index information indicating the color of the pixel, pixel information which is information on the pixels constituting the graphic is generated, and information indicating the index information and the color of the pixel itself is generated. Is stored in another storage area, and a gradation information generation unit generates gradation information for converting the generated pixel information to draw the pixel, and outputs information. The generation unit generates output information for executing image formation output based on the generated gradation information.
Another aspect of the present invention is a control program, the step of obtaining a drawing command obtained based on a page description language, and information in which information is collected for each figure to be drawn. Generating graphic information including information related to transparent drawing based on the acquired drawing command; and, based on the generated graphic information, coloring information of pixels constituting the graphic, attribute information of the pixels, and the pixels Storing information relating to translucent drawing of the figure formed by the storage area reserved for each piece of information, and storing index information indicating the color of the pixel as the color information of the pixel A step of generating pixel information that is information on the pixels that constitute the image, and a color associated with the index information and information indicating the color of the pixel itself A step of holding reference information in another storage area, a step of generating gradation information for rendering the pixel by converting the generated pixel information, and an image based on the generated gradation information Generating the output information for executing the formation output, and causing the image forming apparatus to execute the step.

  According to the present invention, it is possible to improve the access efficiency to the pixel data stored through the multi-value rendering process in the multi-value rendering process for the intermediate (pixel) data of the PDL for which the translucent rendering process is set.

1 is a diagram illustrating an outline of a hardware configuration of an image forming apparatus according to an embodiment of the present invention. It is a block diagram which shows the software structure of the controller of an image forming apparatus (FIG. 1). It is a block diagram which shows the module structure of the PDL part (refer FIG. 2) which has a drawing core module. It is a figure which shows an example of the drawing command of PostScript. It is a figure which shows the example of a setting of the function I / F which a drawing module I / F performs according to a drawing command (FIG. 4). It is a conceptual diagram which shows the data structure used for preservation | save of intermediate data common to a drawing object. An example of a correspondence table of ID numbers and drawing commands is shown. It is a conceptual diagram which shows the data structure of each plane of the pixel data drawn by the multi-value drawing part based on intermediate data. It is a conceptual diagram which shows the format which integrated both pixel attribute and the plane of destination transmission. It is a figure which shows the example of the look-up table which concerns on this embodiment. It is a figure which shows the data structure in a hash method. It is a figure which shows the information contained in 1 byte of an attribute plane. It is a conceptual diagram explaining the relationship between the band data and page data in a banding process. It is a flowchart which shows the drawing process with respect to band data.

Embodiments of an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings. In the present embodiment, an image forming apparatus having a translucent rendering process function and an efficient rendering information generation process will be described.
FIG. 1 is a diagram showing an outline of a hardware configuration of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus receives a print command from a host PC (Personal computer) 20 and controls each part of the image forming apparatus to operate the printer engine 30 according to the received print command. A printer engine 30 that prints an image on paper, and an operation panel 40 that functions as a user interface. As will be described later, the controller 10 receives a print command represented by PDL created by the host PC 20, generates image data for print output based on the received print command, and uses this image data. The printer engine 30 is operated. The operation panel 40 also has a display unit that informs the user of device conditions such as the operation state of the image forming apparatus, and an input unit that allows the user to input instructions for operating conditions to the image forming apparatus.

The controller 10 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, an NV (Nonvolatile) RAM 14, a network interface (I / F) 15, an engine I / F 16, a panel I. / F17 each element.
The CPU 11 executes software program instructions. The ROM 12 is a memory that stores a program for operating the CPU 11. The RAM 13 is a memory used as a page memory created by the controller software or a work memory necessary for the software operation by the CPU 11. The nonvolatile NVRAM 14 is a memory that stores setting conditions such as printing conditions of the image forming apparatus.
The network I / F 15 is an I / F for exchanging data with the host PC 20 connected on the network. The engine I / F 16 is an I / F for exchanging print instructions and the like with the printer engine 30. The panel I / F 17 is an I / F for inputting / outputting data to / from the operation panel 40.

The controller 10 records a program for generating image data for print output on the basis of the received print command in a part of the program stored in the ROM 12, and this program is driven by the CPU 11 to be described later. The means for realizing the functions shown in FIGS. 2 and 3 are configured.
The medium for recording the program is not limited to the ROM 12, but is read by a computer such as an HDD (Hard Disk Drive), a CD (Compact Disk) -ROM, an MO (Magnetic Optical Disk), a DVD (Digital Versatile Disk), or the like. Possible recording media can be used. The program may be provided by being stored on a computer connected to a network (not shown) such as the Internet and downloaded via the network.

FIG. 2 is a block diagram showing a software configuration of the controller of the image forming apparatus (FIG. 1).
Under the control of the printer control system unit 104, the software configuration in the controller 10 includes a network I / F unit 102 for exchanging data with the host PC 20, a panel I / F unit 103 for controlling the operation panel 40, and received prints. A PDL unit 105 that generates image data for print output based on a command (print data) and an engine I / F unit 106 that gives a print instruction to the printer engine 30 are included.

FIG. 3 is a block diagram showing a module configuration of a PDL unit (see FIG. 2) having a drawing core module.
The PDL unit 105 analyzes the print command described in the PDL received via the printer control system unit 104, and the image data for drawing processing and print output based on the analysis result of the PDL parser unit 120 It comprises a drawing core module 110 that performs the conversion process. That is, the PDL parser unit 120 functions as a drawing command acquisition unit that acquires a print command that is a drawing command.
The drawing core module 110 includes the drawing module I / F 113, the intermediate data storage unit 114, the multi-value drawing unit 115, the color conversion unit 116, and the CMYK binary conversion unit 117.

The drawing module I / F 113 is an I / F for receiving text, images, vector graphics, and drawing setting information as analysis results from the PDL parser unit 120.
The intermediate data storage unit 114 has a function for storing drawing data representing drawing objects such as text, images, vector graphics, and drawing setting information such as color values and settings of semi-transparent drawing processing (described in detail later). Part.
The multi-value rendering unit 115 is a functional unit for rendering pixel data in the color space designated by the intermediate format storage unit 114.
The color conversion unit 116 is a functional unit for converting data drawn in multiple values by the multi-value drawing unit 115 into device colors (device-dependent characteristics).
The CMYK binary conversion unit 117 is a functional unit for performing halftone processing on the device colors processed by the color conversion unit 116 with CMYK (C: cyan, M: magenta, Y: yellow, K: black) binary. .
Note that the color space of the multi-value drawing unit 115 follows that specified as the drawing color space at the beginning of the page. When the RGB color space is designated, rendering is performed with 8 bits for each color of RGB.

With reference to FIG. 3 showing the configuration of the PDL unit 105 having the drawing core module 110, the flow of processing of a print command represented by PDL will be described.
First, the PDL parser 120 analyzes the PDL of the print command. In this embodiment, the PDL parser 120 has the functions of PostScript, PDF (Portable Document Format), PCL (Printer Control Language), XPS (extended markup language Paper), etc. In response to the analyzed PDL, the drawing module I / F 113 of the drawing core module 110 is called.
The drawing module I / F 113 obtains drawing data representing drawing objects such as images, graphics, and characters, and drawing setting information such as color values, brushes, translucent drawing processing (detailed later), and line shapes. As an I / F, it functions as an I / F corresponding to all PDL drawing.

Taking PostScript as an example, the drawing module I / F 113 responds to a drawing command by the following operation.
In PostScript, for example, a drawing command as shown in FIG. 4 is issued. In other words, this drawing command has a color of (R, G, B) = (0.5, 0.0, 0.0) in the RGB color space, and the lower left and upper right coordinates with the lower left corner of the page as the origin. A command for drawing a rectangle designated by (100, 100) and (200, 200) is described.
In response to this drawing command, the drawing module I / F 113 calls an I / F for setting a color, and then calls an I / F for setting coordinates and an I / F for specifying fill in order to set a rectangular area. Thus, a rectangle can be drawn according to the drawing command.

FIG. 5 is a diagram illustrating a setting example of the function I / F performed by the drawing module I / F 113 according to the drawing command at this time.
The function I / F is converted into a function sequence in accordance with the drawing command of FIG. 4 as described in FIG. The first argument of setcolor in the function sequence of FIG. 5 specifies the RGB color space, and the second to fourth arguments specify the color value of each RGB color in the range of 0.0 to 1.0. In the example of FIG. 5, (0.5, 0.0, 0.0) corresponding to the drawing command of FIG. 4 is described.
In addition, the rectangle in the function sequence of FIG. 5 is designated as the upper left coordinate and the lower right coordinate by the rectangle drawing function. In the example of FIG. 5, (100, 100, 200, 200) corresponding to the drawing command of FIG. 4 is described.
Similarly, other languages can call the drawing module I / F 113 to perform drawing according to the drawing command.

After the drawing module I / F 113 is called, drawing data and drawing setting information obtained by the intermediate data storage unit 114 via the drawing module I / F 113 are stored as intermediate data on a memory or a file.
Explaining with the operation example of the drawing module I / F 113 described above, in the setcolor function, an RGB color space and a color value (0.5, 0.0, 0.0) are set, and these are set as one of the drawing setting information. obtain.
Data for modifying drawing data (drawing objects such as images, graphics, and characters) is called a graphics state, and a color space and color values are stored in the memory as a graphics state. The graphics state includes a semi-transparent rendering process parameter, a raster operation value, a line width and the like in addition to a color space and a color value.
The graphics state has a data structure common to each object when saved in association with drawing data representing drawing objects such as graphics, images, graphics, characters, and the like.

FIG. 6 is a conceptual diagram showing an example of a data structure used for storing intermediate data common to various drawing objects. In FIG. 6, (A), (B), and (C) show examples of data structures when graphics states (Gstatus) are stored in association with three types of drawing objects, respectively. The data section 601 stores data representing a graphics state (Gstatus) and the data section 603 stores drawing data representing a drawing object. That is, as shown in FIG. 6, the information is graphic information in which information is collected for each graphic to be drawn, and the drawing module I / F 113 functions as a graphic information generating unit.
A data portion 601 for storing data representing the graphics state (Gstatus) of the intermediate data includes, as data for modifying the drawing data, a color space, a color value, a line width, and a semi-transparent drawing process parameter (semi-transparent value). ), Setting information common to rendering such as a Raster Operation value is stored. In the example shown in FIG. 6, the ID number of the drawing data representing the drawing object comes next with the Gstatus record of the fixed length size at the head.

The ID number is associated with a drawing command (drawing object).
FIG. 7 shows an example of a correspondence table between ID numbers and drawing commands. In the example of FIG. 5, five types of drawing commands are shown. ID = 0x00 is a rectangle drawing (Rectangle), ID = 0x01 is a straight line drawing (LineDraw), ID = 0x02 is an area filled with a straight line (LineFill), ID = 0x03 is an Image drawing, = 0x04 indicates character drawing.
Further, after the padding byte and flag following the ID number, an argument of a drawing function corresponding to the drawing command, image data, code data, and the like are stored.
When an example of a call by a function I / F performed by the drawing module I / F 113 shown in FIG. 5 in response to a rectangle drawing command is taken, intermediate data stored at this time, that is, the graphic of (A) in FIG. In the G status, a color space and a color value are stored, and coordinates of the rectangle are stored as left = 100, top = 100, right = 200, and bottom = 200. The byte next to the ID number is a padding byte and 0 is entered. The flag is used as an attribute of a drawing command. As an example of the attribute, when the Rectangle command is set to Clip (command for limiting the drawing area), the bit indicating Clip is set to ON.

Next, the operation of the multilevel drawing unit 115 will be described.
The rendering process performed by the multi-value rendering unit 115 is a process of rendering pixel data based on the intermediate data stored by the intermediate data storage unit 114. Image data processing for print output (color conversion, halftoning, etc.) Performed in the first stage. The pixel data of the rendering result is stored in the memory in dot order, that is, in the order of arrangement of the pixels of the page image. In other words, the information generated by the multi-value drawing unit 115 is information of pixels constituting the graphic to be drawn, that is, pixel information, and the multi-value drawing unit 115 functions as a pixel information generation unit.
Specifically, according to the set color space, a color plane that represents an 8-bit (multi-value) color value for each color, a pixel attribute plane that associates the attribute of each pixel with the color plane, and translucent used for translucent rendering processing The pixel data of each plane of the destination transmission plane representing the value is drawn dot-sequentially.

8A to 8D are conceptual diagrams showing the data configuration of each plane of pixel data drawn by the multi-value drawing unit 115 based on the intermediate data.
The color plane shown in FIG. 8A stores color values in a dot order format for pixels for drawing a page area. In the example shown in the figure, the color space is RGB (R is Red, G is Green, and B is Blue), and RGB (8 bits for each color) pixel color values are stored in a dot order. As shown in the figure, this color plane is implemented by securing 4 bytes per pixel. Note that P in FIG. 8A is a putting byte (padding byte), and when the color space is RGB, 0 is padded with the value of P. When the color space is CMYK, all 4 bytes are used as pixel color values.
The color plane shown in FIG. 8B is a configuration according to the gist of the present embodiment, and stores the color values in the store sequential format for the pixels for drawing the page area, as in FIG. 8A. Here, the mode shown in FIG. 8B does not store 8-bit pixel color values for each color of RGB, as in the mode of FIG. 8A, but rather a 256 color, that is, 8-bit lookup table. 8 bit data (indicated as “Id” in FIG. 8B) is stored. Therefore, in the case of the color plane shown in FIG. 8B, 1 byte is secured per pixel.

The pixel attribute plane shown in FIG. 8C is lost when the drawing data representing the drawing object shown in the intermediate data (see the data structure shown in FIG. 6) described above is drawn. Since the characteristics of each drawing object cannot be reflected in the image data for print output, it is created to associate the drawing object as a pixel attribute.
In this embodiment, the data value (indicated as “A” in FIG. 8C) representing the attribute of each pixel has 8 bits. If there are 8 bits, at least 8 types of attribute values can be expressed by expressing each attribute with each bit. A data value representing an attribute is used for determining whether a drawn pixel belongs to a drawing object type such as a character, an image, or a graphic. It should be noted that in order to determine whether the type of the drawing object to which the pixel belongs belongs to any one of character, image, and graphics, it is sufficient to be able to determine four types including those not belonging to any, at least 2 It can be judged by bit.
Furthermore, in the pixel attribute plane according to the present embodiment, the color plane data is in the format of the color data itself as shown in FIG. 8A or the format of the lookup table as shown in FIG. Is included (hereinafter referred to as color plane format information). This color plane format information can be one bit because it is sufficient to identify two types of cases, FIG. 8A and FIG. 8B.
The destination transmission plane used for the translucent drawing process shown in FIG. 8D has a translucent value (indicated as “T” in FIG. 8D) used for the translucent drawing process of the drawing destination (destination). It has 8 bits. The method of using the transmission plane will be described in detail later.

Each plane in FIGS. 8A to 8D is designated by extracting the intermediate data stored in the data structure shown in FIG. 6 in the order of storage when the memory can be secured for one page. It is created by writing to the address (coordinate data). Each of the planes in FIGS. 8A to 8D is a storage area on a memory reserved in advance for the color information of the pixel, the attribute information of the pixel, and the information on the semi-transparent drawing of the figure formed by the pixel.
In the data structure shown in FIG. 6, by identifying a drawing command (ID number), a drawing object as a pixel attribute and a pixel address (coordinate data) are obtained. Based on these data, a pixel attribute plane is obtained. Write data to. At the same time, a color space and color value, a translucent value as a parameter of the translucent rendering process, a raster operation value, and the like are obtained from Gstatus (graphics state) of the rendering command. Based on these data, the color plane, Write data to each Nation transparent plane.
At this time, as shown in FIG. 8B, when the color value represented on the color plane is represented by an index value, the index value is associated with the color value by the color lookup table. Thus, the color value can be restored by referring to the lookup table in the subsequent image processing. By adopting an index value, it is possible to represent 1 pixel of data in 1 byte,
The amount of data to be processed can be reduced.
Further, when writing, the following Raster Operation or translucent drawing process is performed.

ROP (Raster Operation) is image processing used in a graphics engine of Windows (registered trademark) OS (Operating System), and is a process of performing bit operations on color values of graphics overlapping in the same area for each color of RGB. Bit operations include OR, XOR, and AND.
On the other hand, the translucent rendering process is an image process used in XPS or PDF supported by Windows (registered trademark) Vista (registered trademark), and specifies the transmission ratio of color values overlapping the same area from 0% to 100%. This is a process of rendering translucent.
Usually, ROP and translucent drawing processing are not used at the same time, but they may be used.

When ROP is performed, writing is not performed on the destination transmission plane (see FIG. 8D). In addition, the OR, XOR, and AND bit operations are performed between the color values of the overlapping images (pixels) by using the raster operation value (ID) obtained from Gstatus (graphics state), and the calculation result is calculated for the corresponding pixel of the color plane. Write as RGB color value (8 bits for each color) data.
Note that there are 256 IDs from 0 to 255 that designate ROPs stored in Gstatus (graphics state), and each bit operation is defined in advance. In accordance with this definition, bit calculation of the source and destination is performed for each color of RGB.
In addition, after performing the bit operation, the pixel object information (character, image, graphics) drawn on the pixel attribute plane is written dot-sequentially as the pixel attribute.

The translucent drawing process is performed by the following processing method.
The semi-transparent rendering process employed in this embodiment can be broadly divided into a case where processing conditions are set only for source data to be rendered, source data (overlapping data), and destination data after rendering (drawing destination data). In some cases, processing conditions are set for both (data).
In the former case, if the color value of each pixel of the source and destination is source: S, the destination: D, and the translucency value of the source (between 0 and 1) is translucent value: α, The color value NewD after the transparent drawing process can be calculated based on the following formula (1).
NewD = S * α + (1−α) * D (1)
The process of calculating the color value after the semi-transparent drawing is performed for each color of RGB. Further, when the source α processing condition is set only for the source data as described above, the destination transmission plane (see FIG. 8D) is not used.

Also, when setting the processing conditions for both the source data and the destination data after drawing,
As: Source translucent value Ad: Destination translucent value Ad ′: Destination translucent value after drawing Cs: Source color value Cd: Destination color value Cd ′: Destination color value after drawing Ad 'And Cd' can be calculated based on, for example, the following formulas (2) and (3), respectively.
Ad ′ = (1-As) * Ad + As (2)
Cd ′ = ((1−As) * Ad * Cd + As * Cs) / Ad ′ (3)

The destination translucent value Ad ′ after drawing calculated based on the above equation (2) is drawn on the corresponding pixel of the destination transmission plane (see FIG. 8D).
The source translucency value As is set to Gstatus (graphics state).
When the multi-value drawing unit 115 draws the drawing object of the intermediate data in the page memory, the translucent value and the color value used for the semi-transparent drawing process of the drawing target object set in Gstatus are extracted, and the color of the destination Calculate the new destination color value and destination translucency value using the color value set for the plane, and the destination translucency value set for the destination transmission plane, respectively. Update the value of.
Note that, since the processing method of the translucent rendering process is determined as one method when processing the same page, a plurality of processing methods will not be mixed.

In the above description, the case of multi-value drawing processing in which RGB data is written to the color plane shown in FIG. 8A has been described. However, when drawing with 8 bits for each color of CMYK, the color plane shown in FIG. In this case, what is expressed by 32 bits of PRGB having padding bytes P per pixel in the above may be replaced with drawing by 32 bits of CMYK. That is, it is not necessary to provide the putting bit P. In the case of gray scale, drawing is performed with 8 bits per pixel.
In addition, it is provided with means for determining whether or not there is a semi-transparent drawing process by checking whether or not the Gdata of the intermediate data has a semi-transparent value used for the semi-transparent drawing process. When it is determined that there is no processing, a rendering process may be performed in which multivalues are represented by color values in the CMYK binary format as a plane representing color values.

Here, a storage method of pixel data stored by the multi-value drawing process will be described.
In this type of image forming apparatus, pixel attributes and translucent values are generated as pixel data in addition to color values by multi-value drawing processing, and these data are stored for use in print output. In this pixel data storage method, when the pixels are arranged in order as in the prior art, one pixel is accessed in units of 5 bytes, which is accessed by a CPU composed of 4-byte (32-bit) registers. As described above, the efficiency is reduced.
Therefore, in this embodiment, a storage method that can improve the access efficiency when reading the stored pixel data when used for print output is adopted.

As an example of storing pixel data, an example of conceptually using three different planes has been described with reference to FIG. However, the actual storage mode of each plane does not need to be stored using a separate storage area, and a method of storing planes in an integrated manner can be adopted.
In this embodiment, first, as shown in FIG. 8A, color values are stored dot-sequentially at 4 bytes per pixel in the color plane, so access from a CPU having a 4-byte configuration register. Convenient to. Therefore, the color plane is stored in the format shown in FIG.

Further, the pixel attribute plane only needs to secure 1 byte per pixel as a capacity necessary for storing object information (characters, images, graphics) as the pixel attribute. It is only necessary to secure 1 byte per pixel as a capacity necessary for storing the nation translucency value. Therefore, a method of using an integrated plane that stores both the pixel attribute plane and the destination transmission plane together at 2 bytes per pixel is adopted. According to this method, it is possible to acquire object information as a pixel attribute and a destination translucent value of two pixels in one access.
FIG. 9 is a conceptual diagram of a format in which both the pixel attribute plane and the destination transmission plane are integrated. As shown in the drawing, the pixel attribute A and the destination translucent value T are collectively stored in a dot order format for the pixels in which the page area is drawn in the integrated plane.

By using the pixel data storage method described above, it is possible to perform access by using 4 bytes of the color plane and 2 bytes of the integrated (pixel attribute + destination translucent value) plane as one pixel. That is, one pixel data can be read out by 1.5 times of read commands, and pixel data can be read out with a small number of commands, so that the processing efficiency can be improved.
In addition, since 4 bytes are secured in the color plane, even in the case of CMYK, there is no change in that one pixel data can be read with a read command of 1.5 times, and both RGB and CMYK can be handled efficiently. It is possible to improve the efficiency of processing image data for print output such as color conversion and halftoning performed on the pixel data stored in the plane.

  Furthermore, as described above, in the present embodiment, the index value is stored dot-sequentially at 1 byte per pixel by employing a look-up table in the color plane information. In this case, when accessing from a CPU having a 4-byte configuration register, an index value for four pixels can be acquired by one access. In order to read 4 pixels in the integrated plane described above, it is necessary to access twice, so that data of 4 pixels can be read out with a total of 3 accesses, and the processing efficiency of image processing can be further improved. it can. Hereinafter, a case where a lookup table is employed will be described.

FIG. 10 is an example of a lookup table according to the present embodiment. As shown in FIG. 10, in the lookup table according to the present embodiment, the color value, that is, information indicating the color of the pixel is associated with an index value for identifying each. That is, the lookup table according to the present embodiment is used as color reference information. As shown in FIG. 10, in the present embodiment, 256 color values from index 0 to 255 can be registered. As shown in FIG. 10, the color values constituting the table may be 8-bit RGB or CMYK for each color, and are used according to the color space of the intermediate data. The element values of the lookup table shown in FIG. 10 are all initialized to “0” at the initial stage when the multi-value drawing means is executed first.
Next, a method for creating the lookup table shown in FIG. 10 will be described. As described above, the multi-value rendering unit 115 sequentially renders the intermediate data rendering object as described in FIG. At that time, the multi-value rendering unit 115 acquires the color data value included in GStatus and checks whether the color of the color data is registered on the lookup table. If registered, the multi-value rendering unit 115 acquires the index value, and stores the index value in the color plane as described in FIG. 8B.
On the other hand, when the color of the color data included in GStatus is not registered, the multi-value rendering unit 115 newly registers the color data in the lookup table and acquires the index value. Then, the multilevel drawing unit 115 stores the acquired index value in the color plane. By such processing, the index value is stored in the color plane as shown in FIG.

Next, a method for determining whether or not the color data included in GStatus is registered on the lookup table will be described. In the present embodiment, the multi-value rendering unit 115 determines whether color data is registered on the lookup table using a method called a hash method. Hereinafter, the hash method will be described.
The hash method is a method of obtaining a hash value by converting a search target (in this case, the color value of color data) using a hash function, and performing a search based on the hash value. The search target is narrowed down in advance. As a result, the processing load on the search process can be reduced. FIG. 11 is a diagram illustrating a data structure in the hash method. As shown in FIG. 11, in the hash method, a hash value table that is a list of hash values is provided. In this embodiment, a table of 256 values from “0” to “255” is provided. It is provided as a hash value table.
In addition, hash records associated with the color data registered in the lookup table are registered in the hash values included in the hash value table. FIG. 11 shows an example in which two hash records are registered for the hash value “2” in the hash value table. As shown in FIG. 11, each hash record includes data of “Id”, “Tblptr”, and “Next”. “Id” indicates the index value of the corresponding lookup table. “Tblptr” is a pointer to the color data of the corresponding lookup table. “Next” is a pointer to the next hash record registered in the same hash value. As shown in FIG. 11, when there is no next record, “Next” is a Null value.
In the example of FIG. 11, two hash records are registered in the hash value “2”, and the two hash records are associated with the index values “0” and “1” of the lookup table, respectively. . This indicates that the hash values of the color data having the index values “0” and “1” in the lookup table are both “2”.

Next, a method in which the multilevel drawing unit 115 obtains an index value using the hash method will be described. First, when color data is obtained from GStatus of intermediate data, the multi-value rendering unit 115 calculates a hash value. In the present embodiment, the multi-value drawing unit 115 obtains a hash value using the following formula (4) as a hash function.
Hash (x) = (R + G + B)% 256 Formula (4)
The above equation (4) indicates that the remainder obtained by adding the R, G, and B values obtained from GStatus and dividing by 256 is obtained as the hash value. This 256 is equal to the table size of the hash value table shown in FIG. 11, and any value from 0 to 255 is calculated as the hash value by the equation (4). Even when the values of R, G, and B are different from each other, the sum is the same, and as a result, the hash values may be the same. In this case, a plurality of records are registered in one hash value as in the hash value “2” in FIG.
When the multi-value rendering unit 115 obtains the hash value of the color data according to the equation (4), the multi-value rendering unit 115 refers to the lookup table associated with the hash record registered in the hash value, and calculates the R, G, and B values. Compare. Until color data having the same R, G, B value is found in the lookup table or until the end of the list of hash records registered in the hash value is reached, that is, until “Next” becomes a Null value. , R, G, and B values are repeatedly compared to determine whether the same color data has already been registered in the lookup table.
When color data having the same R, G, and B values is found in the lookup table, the multi-value rendering unit 115 determines that the color data of the pixel being processed is already registered in the lookup table. . On the other hand, when color data having the same R, G, and B values is not found in the lookup table and reaches the end of the list, the multi-value rendering unit 115 determines that the color data of the pixel being processed is the lookup table. The color data is registered in the lookup table.

In the process of registering color data in the lookup table, first, a new index value in the lookup table is acquired. If this index value is stored as, for example, a global variable and added one time each time new data is registered in the lookup table, the index value can be assigned in order from “0” to “255”. .
When the new index value in the lookup table is acquired, the multi-value rendering unit 115 writes the color data acquired from the GStatus of the intermediate data in the lookup table corresponding to the acquired new index value. For example, when a second hash record having a hash value “2” in FIG. 11 is newly registered, color data is written into data having an index value “1” in the lookup table.
Then, the multi-value rendering unit 115 writes the address on the lookup table in which color data is newly registered in “TblPtr” of the hash record, and uses the address of this hash record as “Next” of the previous hash record. Write to. In addition, the multi-value rendering unit 115 stores the new index value acquired first in the color plane. Finally, the multi-value rendering unit 115 writes a bit indicating that the color plane of the target pixel is in the look-up table format in the attribute plane. By such processing, the pixel data storage processing by the multi-value rendering unit 115 is completed.
FIG. 12 shows an example of information assigned to each bit in one byte in the attribute plane. As shown in FIG. 12, in each byte of the attribute plane according to the present embodiment, 2 bits are assigned as information indicating the attribute of each pixel. One bit is assigned to the information indicating the format of the color plane. As described above, the data of each plane such as the attribute plane is generated by the multilevel drawing unit 115. That is, information as shown in FIG. 12 is generated by the multi-value drawing unit 115. Then, the color conversion unit 116 determines the color plane processing method with reference to the attribute plane information as shown in FIG.

Here, as described in FIG. 10, the number of color data that can be registered in the lookup table in this embodiment is 256. However, depending on the image to be imaged and output, 256 or more colors may be required.
The multi-value rendering unit 115 cannot recognize how many colors are used for the rendering object on the intermediate data. There is a method of counting the number of colors when registering intermediate data, but the number of colors may increase in the process of further drawing. For example, in the ROP process, a new color is generated by performing bit operations on source data and destination data. Similarly, colors increase in translucent drawing. In such a case, the number of registered lookup tables may be insufficient.
Specifically, as described above, when the index value stored as the global variable is “256”, it indicates that the lookup table is already full. In this case, the multi-value rendering unit 115 stores the pixel data of the color plane in the color data format as described with reference to FIG. Then, a bit indicating that the color plane of the target pixel is in the color data format is written in the attribute plane.
Through such processing, the color plane data is stored as much as possible by using the lookup table format to reduce the number of memory accesses, and even when the lookup table is full, the color data itself is used. It is possible to store information in
In this embodiment, since the number of color values that can be registered in the lookup table is 256, the index value threshold value for switching the color plane format from the index format to the color data format is set to 256. This value is determined according to the number of color values that can be registered in the lookup table. That is, the multi-value drawing unit 115 switches the color plane format when the number of color data already registered in the lookup table reaches a predetermined threshold.

In addition to the case where the look-up table is full, the color data itself should be registered without using the look-up table. For example, when the drawing data on the intermediate data is full-color image data, the total number of colors used is likely to exceed 256 colors. In such a case, by canceling the look-up table specifications in advance, pixel data for drawing characters and figures can be preferentially registered in the look-up table, and memory access can be made efficient.
As a specific process, the multi-value drawing unit 115 refers to the drawing data ID number in the intermediate data, and determines whether or not the drawing data is full color. Of the drawing data ID numbers shown in FIG. 7, ID = 0x03 is a full color image, ID = 0x04 is a color value using an index table, that is, an index image, and an index value of 1, 2, 4 or 8 bits. It is an image that has. Here, 1, 2, 4, and 8 bits respectively indicate the number of bits of the color value, and when it is 1, it indicates 1 bit, that is, monochrome. Hereinafter, cases of 4 colors, 16 colors, and 256 colors are shown. The number of bits of this index value is stored in, for example, flag in the intermediate data shown in FIG.
When the ID number of the drawing data is 0x03, the multi-level drawing unit 115 draws with RGB 24-bit full color data without searching the lookup table because the drawing data is a full color image. Similarly, when the ID number is 0x04 and the number of bits is 8 bits, that is, 256 colors, drawing is performed with RGB 24-bit full color data. Then, a bit indicating that the color plane of the target pixel is in the color data format is written in the attribute plane.

Next, banding processing will be described.
In the above description, the multi-value drawing unit 115 has been described as being able to secure one page of memory capacity necessary for processing. However, when the memory capacity of one page cannot be secured, the drawing process is performed by a method called banding processing. Do.
FIG. 13 is a conceptual diagram illustrating the relationship between band data and page data in the banding process. In the banding process, when the controller 10 cannot secure a memory capacity for one page, the page data is divided into a plurality of parts in the height direction as shown in FIG. In the example of FIG. 13, a band memory having a height of 1024 is secured), and processing is performed to enable page data processing.

  In the banding process, when the multi-value drawing unit 115 acquires intermediate data necessary for the drawing process, the multi-value drawing unit 115 accesses the memory in band units and executes the drawing process by storing the acquired intermediate data in the secured band memory. To do. Band data other than intermediate data that can be saved in the band memory is compressed or saved in a hard disk (not shown) or the like. The band data waiting for processing in a compressed form is decompressed and loaded onto the band memory when a drawing request is made. Even when the hard disk is saved, it is loaded into the memory when a drawing request is made. When the drawing is finished and the next band drawing request is made, the image is compressed or stored in the hard disk.

When drawing is performed by banding processing based on the intermediate data (refer to the data structure shown in FIG. 6), the coordinate data of each drawing object is clipped to each band data and drawn in the band memory.
The pixel data to be saved in the band memory as a drawing result is in the format shown in the examples of FIGS. 8 and 9, but the memory capacity can be saved by applying a different format for each band and saved in the band memory. There is no need to perform useless access operations when using the pixel data. For example, if band 0 has only gray data, the color plane may be only a 1-byte (8-bit) gray plane, and the integrated plane for pixel attribute and destination transmission does not change. Become. On the other hand, when color data is included in band 1, the 4-byte PRGB plane and the integrated plane of pixel attributes and destination transmission are 2 bytes unchanged. The color used in each band can be determined by examining the color data included in the Gstatus (graphics state) of the intermediate data.

Here, a drawing process for band data will be described with reference to a flowchart shown in FIG.
As shown in the flow of FIG. 14, when the banding operation is started, first, one band data is acquired from the band data bands 0 to 6 of the page data to be rendered according to a predetermined order (step S1401).
Next, the drawing target pixels in the acquired band data are designated dot-sequentially (step S1402), and Gstatus (graphics state) of intermediate data for the designated pixel is obtained (step S1403).
Next, the color value included in Gstatus of the designated pixel is checked to determine whether the color value is monochrome or color (step S1404).

If it is determined from the color value checked in step S1404 that the pixel is a color (step S1404—NO), it is next determined whether or not the target pixel data is in the form of a lookup table (step S1404). Step S1405). The determination in step S1405 is processed by determining whether the lookup table is full and whether it is a full color image, as described above.
In the case of the look-up table format (step S1405—YES), the index value is acquired by the method described above and written to the color plane of the band memory, and if it is a new color, the color data is registered in the look-up table. (Step S1405).
On the other hand, when the color data format is used instead of the look-up table format, RGB or CMYK color values are written in the PRGB format (4 bytes) in the color plane of the band memory (step S1406).
On the other hand, if it is determined from the color value that the pixel is monochrome (step S1404—YES), the density value is written in the monochrome format (1 byte) on the color plane of the band memory (step S1407).
When the translucent rendering process is set, the color value or density value to be written in the above writing step is calculated according to the setting condition, and the calculated color value is written.
Next, the object information (character, image, graphics) as the pixel attribute of the pixel is written in the pixel attribute plane of the band memory (step S1408). In the processing of step S1408, as described above, information indicating whether the color plane format of the corresponding pixel is a lookup table format or a color data format is also written.
Furthermore, when the translucent rendering process is set, the destination translucency value of the pixel is calculated (see the above formula (2)), and the calculated value is written to the destination transmission plane of the band memory. The destination translucent value of the band memory is updated (step S1409).

After the pixel data is drawn for the pixel specified in step S1402, it is checked whether the drawing process for all the pixels in the current band has been completed (step S1410).
If there is an unprocessed pixel in the current band (step S1410-NO), the process returns to step S1402, and the next pixel is designated dot-sequentially and the drawing process is performed as described above.
On the other hand, when the drawing processing for all pixels in the current band is completed (step S1410—YES), the band data on the band memory after the drawing processing is transferred, and the band memory is released to prepare for the next drawing (step). S1411). Note that the band data after the drawing process is stored in, for example, a hard disk and waits for processing to print output image data.
Next, all the pixel data of the band data acquired in step S1401 is drawn, and when the band memory can be used, it is confirmed whether or not the drawing processing of all the bands of the page data to be drawn is completed. (Step S1412).
If there is unprocessed band data in the page data to be rendered (step S1412—NO), the process returns to step S1401, and the next band data is acquired and the rendering process is performed as described above.
On the other hand, when the drawing process for all band data of the page data to be drawn is completed (step S1412—YES), this drawing process is terminated.

Returning to the processing of the drawing core module 110, an image processing unit subsequent to the multi-level drawing unit 115 that has performed multi-level drawing processing will be described. The subsequent image processing unit performs processing for converting pixel data of the multi-level page memory drawn by the multi-level drawing unit 115 into image data for print output.
First, the color conversion process performed by the color conversion unit 116 will be described.
The color conversion processing is mainly processing that performs color matching processing, BG / UCR (Black generation and Under Color remove 1) processing, and converts the data into a device CMYK (image data used for image output by the printer engine 30).

The color conversion unit 116 performs color matching processing using pixel data stored in each of the color plane, the pixel attribute plane, and the destination transmission plane drawn by the multi-value drawing unit 115. At this time, the color conversion unit 116 refers to information indicating the information format of the color plane in the attribute plane information, and acquires color data from the lookup table when the format is the lookup table format.
In color matching, characteristics dependent on the output device (printer engine 30) are corrected by adjusting color conversion parameters so that an image to be printed out has an intended color characteristic.
The color conversion unit 116 according to the present embodiment receives input of 8-bit pixel data for each RGB color of the PRGB color plane obtained by the multi-value rendering process, and performs a color matching process by color conversion on this data. The 8-bit data for each color RGB after color matching is overwritten at the same memory address.

  When performing color matching processing, refer to the pixel data of the pixel attribute plane obtained by the above multi-value rendering processing and apply matching processing parameters according to the type of character, image, or graphics object. Appropriate color matching can be performed to improve image quality. Similarly to the type of object, by referring to the destination translucent value for the destination transparent plane obtained by the multi-value rendering process, the matching processing parameter corresponding to this translucent value is applied. Appropriate color matching can be performed to improve image quality.

Further, BG / UCR processing is performed on pixel data of 8-bit RGB colors of the PRGB color plane obtained by the multi-value rendering processing or pixel data obtained from the lookup table based on the index value. The output of this BG / UCR process is CMYK. Data subjected to BG / UCR conversion for each pixel is overwritten on the same memory address as that stored as the original PRGB color plane. Since the color value of the PRGB color plane is 4 bytes, it can be stored at the same address after conversion.
As described above, the pixel data stored in each plane by the multi-value rendering process by the multi-value rendering unit 115 is converted into a color space and color data by the color matching process and the BG / UCR process in the color conversion unit 116. However, no extra memory capacity is required for this data conversion, and no memory is acquired.

The CMYK binary conversion unit 117 converts the multivalued CMYK data processed by the color conversion unit 116 into binary.
The CMYK binary conversion unit 117 receives the CMYK 8-bit color plane data and pixel attribute plane data from the color conversion unit 116, performs halftone processing on the 8-bit pixel data of each CMYK color, and performs binary conversion for each color of CMYK. Save to page memory. In this process, the pixel attribute plane data is used to change the halftone pattern applied to each drawing object.
In other words, the color conversion unit 116 and the CMYK binary conversion unit 117 function as a gradation information generation unit that generates gradation information for drawing pixels based on the pixel information generated by the multilevel drawing unit 115.
Thus, in this embodiment, by using a lookup table as color plane information, the number of pixels from which information can be read out by one access can be increased, and the processing efficiency of image processing can be improved.

In the above-described embodiment, as described with reference to FIG. 10, the case where 256, that is, one byte is provided as the number of color data that can be registered in the lookup table is described as an example. However, this is an example, and it may be more or less.
For example, if the number of color data that can be registered in the lookup table is 16, that is, 4 bits, the information amount of the index value is 4 bits, and 2 pixels of color data can be stored in 1 byte. become. As a result, in the case of a 4-byte CPU, color data for 8 pixels can be read out with a single access. In addition, by making the number of bits of the index value a divisor of 8, one byte of the color plane can be consumed without surplus, and the efficiency of memory access by the CPU can be improved.
Also, the number of color data that can be registered in the lookup table can be made variable. For example, the number of index bits may be changed for each band described above. As a result, the memory capacity can be saved, and unnecessary access operations are not required when using pixel data stored in the band memory. In this case, a lookup table is provided for each bit number of the index. Further, the number of bits of the index of the lookup table applied to the pixel is recorded in the surplus bits of the attribute plane. This makes it possible to control by changing the number of bits of the index for each band.

  10 .... Controller, 11 .... CPU, 30 ... Printer engine, 40 ... Operation panel, 104 ... Printer control system part, 105 ... PDL part, 110 ... Drawing core module, 113 ... Drawing module I / F, 114... Intermediate data storage unit, 115.. Multi-value rendering unit, 116 Color conversion unit 117 117 CMYK binary conversion unit 120 PDL parser unit

Japanese Patent Laid-Open No. 2004-24369

Claims (10)

A drawing command acquisition unit for acquiring a drawing command obtained based on the page description language;
A graphic information generator for generating graphic information in which information is collected for each graphic to be drawn based on the acquired drawing command;
A pixel information generation unit that generates pixel information, which is information of pixels constituting the graphic, based on the generated graphic information;
A gradation information generation unit that converts the generated pixel information to generate gradation information for rendering the pixel;
An output information generation unit that generates output information for executing image formation output based on the generated gradation information,
The graphic information generation unit generates the graphic information including information related to translucent drawing of the graphic based on the drawing command,
The pixel information generation unit stores the coloring information of the pixels constituting the graphic, the attribute information of the pixels, and the information on the semitransparent drawing of the graphic formed by the pixels in a storage area reserved for each information. In addition, the pixel information is generated by storing index information indicating the color of the pixel as the color information of the pixel, and color reference information in which the index information is associated with information indicating the color of the pixel itself. An image forming apparatus that is held in another storage area.   The image forming apparatus according to claim 1, wherein the pixel information generation unit is capable of storing information indicating the color of the pixel itself as the color information of the pixel.   The pixel information generation unit stores information indicating the color of the pixel itself as the color information of the pixel when the graphic to be drawn in the graphic information is full color data. The image forming apparatus described.   The pixel information generation unit stores information indicating the color of the pixel itself as the color information of the pixel when the number of the index information included in the color reference information reaches a predetermined number. The image forming apparatus according to claim 2.   The pixel information generation unit, when the graphic to be drawn in the graphic information is an index image, and the number of bits of an index for identifying the index image is a predetermined number or more, 5. The image forming apparatus according to claim 2, wherein information indicating the color itself is stored.   The image forming apparatus according to claim 1, wherein the number of index information that can be registered in the color reference information is variable. The pixel information generation unit
The pixel information is generated based on the graphic information for each band that is a range of each divided page.
The image forming apparatus according to claim 6, wherein different numbers of index information that can be registered in the color reference information can be used for each band.   The image forming apparatus according to claim 6, wherein different numbers of index information that can be registered in the color reference information can be mixed in the color information of the pixels. The drawing command acquisition unit acquires a drawing command obtained based on the page description language,
The graphic information generation unit generates information on the information to be drawn for each graphic to be drawn and includes graphic information including information related to the translucent drawing of the graphic, based on the acquired drawing command,
Based on the generated graphic information, the pixel information generation unit uses the coloring information of the pixels constituting the graphic, the attribute information of the pixels, and the information on the translucent drawing of the graphic formed by the pixels for each information. And storing the index information indicating the color of the pixel as the color information of the pixel to generate pixel information which is information of the pixels constituting the graphic, and the index information And coloring reference information in which the information indicating the coloring of the pixel itself is associated is held in another storage area,
A gradation information generation unit generates gradation information for rendering the pixel by converting the generated pixel information,
An image data processing method, wherein an output information generation unit generates output information for executing image formation output based on the generated gradation information. Obtaining drawing commands obtained based on the page description language;
Generating the graphic information based on the acquired drawing command, which is information in which information is collected for each graphic to be drawn and includes information related to translucent drawing of the graphic;
Based on the generated graphic information, a storage area reserved for each piece of information on the coloring information of the pixels constituting the graphic, attribute information of the pixels, and information on the translucent drawing of the graphic formed by the pixels Storing in the step,
Generating pixel information which is information of pixels constituting the graphic by storing index information indicating the color of the pixel as the color information of the pixel;
Holding the color reference information associated with the index information and the information indicating the color of the pixel itself in another storage area;
Converting the generated pixel information to generate gradation information for rendering the pixel;
A control program for causing an image forming apparatus to execute output information for executing image forming output based on the generated gradation information.

Images