JP2010220075A - Image forming apparatus, image data processing method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the efficiency of access to pixel data stored through a multiple-value drawing process to intermediate data of PDL with a translucent drawing process set. <P>SOLUTION: In drawing a plane (one byte) representing a pixel attribute and a destination transmission plane (one byte) representing a translucent value for a translucent drawing process in addition to a color plane (four bytes) representing a color value as pixel data of point sequence by a multiple-value drawing process based on intermediate data of PDL, an integrated plane (Fig.9) for collectively storing both the planes of the pixel attribute and the destination transmission in two bytes per pixel is drawn. When reading pixel data of respective planes used for processing image data for print output such as color conversion or half toning, one-pixel data can be read by a reading command of 1.5 times by either of RGB and CYMK, and the efficiency of processing can be improved. <P>COPYRIGHT: (C)2010,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 a processing means for improving access efficiency to intermediate (pixel) data of PDL for which translucent rendering processing is set, an image data processing method and a program used for the image forming apparatus.

  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 Specification), or the like is used, and the image forming apparatus uses a print command described in these PDLs. 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, drawing is performed using the translucent value of the data to be overlaid (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 composed of a register of 4 bytes (32 bits) at present, it is impossible to 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.
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.

The present invention relates to intermediate data storage means for storing intermediate data including image data in an intermediate format obtained by analyzing a page description language in a state in which a drawing object can be identified, and from the intermediate data stored in the intermediate data storage means, Multi-value rendering means that renders pixel data consisting of a plane that represents values and pixel attribute planes that contain rendering objects as attributes, and color conversion that performs color conversion for each object based on pixel data rendered by the multi-value rendering means And an image forming apparatus having gradation processing means for gradation-converting the image data converted by the color conversion means, wherein the intermediate data storage means stores parameters used for the semi-transparent drawing process as intermediate data The multi-value drawing unit draws a picture from the intermediate data stored by the intermediate data storage unit. When the pixel data of each drawn plane is saved, the attribute plane of the drawn pixel and the plane representing the parameter used for the translucent drawing process are collected together. It is characterized by saving.
The present invention includes a step of analyzing intermediate format image data from a page description language, an intermediate data storage step of storing intermediate data including the analyzed intermediate format image data in a state in which a drawing object can be identified, and intermediate data storage From the intermediate data saved in the process, based on the pixel data drawn in the multi-value drawing process and the multi-value drawing process that draws the pixel data consisting of the attribute value plane of the pixel that includes the plane representing the color value and the drawing object as the attribute An image data processing method comprising: a color conversion step for performing color conversion for each object; and a gradation processing step for gradation conversion of image data converted in the color conversion step, wherein the intermediate data storage step is translucent Parameters used for drawing processing are saved as intermediate data, and the multi-value drawing step is saved in the intermediate data saving step In addition to adding a plane representing parameters used for the semi-transparent drawing process to the pixel data to be drawn from the intermediate data drawn, when saving the pixel data of each drawn plane, the attribute plane of the drawn pixel and the semi-transparent drawing process are used. It is characterized in that the parameters to be used are stored together.

  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 the pixel attribute and the transmission plane of a destination. 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 outline of 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.
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 based on the received print command in a part of the program stored in the ROM 12, and the CPU 11 drives this program to be described later. A means for realizing the functions shown in FIGS. 2 and 3 is 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 (Magnet 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).
The software configuration in the controller 10 includes a network I / F unit 102 for exchanging data with the host PC 20 and a panel I / F unit 103 for controlling the operation panel 40 under the control of the printer control system unit 104. 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.
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 a function of analyzing differences in syntax of each PDL such as PostScript, PDF (Portable Document Format), PCL (Printer Control Language), XPS (XML (Extensible Markup Language) Paper Specification), etc. The drawing module I / F 113 of the drawing core module 110 is called corresponding to the analyzed PDL.
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.
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 line drawing (LineDraw), ID = 0x02 is a fill of a region surrounded by 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.
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.

FIG. 8 is a conceptual diagram showing a 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. 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 pixel attribute plane shown in FIG. 8B disappears when 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. 8B) representing the attribute of each pixel has 8 bits. If it is 8 bits, 8 types of attribute values can be expressed by each bit. The attribute usage is used to distinguish whether a drawn pixel belongs to a drawing object such as a character, an image, or a graphic.
The destination transparent plane used for the translucent drawing process shown in FIG. 8C has a translucent value (indicated as “T” in FIG. 8C) 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 FIG. 8 takes out the intermediate data saved in the data structure shown in FIG. 6 in the order in which it is saved when one page of memory can be secured, and writes it to the specified address (coordinate data). It is made by putting.
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 the Gstatus (graphics state) of the rendering command. Write data to each Nation transparent plane. At this time, the color value represented on the color plane can be expressed as an index value. This index value can be restored by associating it with a color value by a color lookup table. By adopting the index value, 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 an image process used in a graphics engine of Windows (registered trademark) OS (Operating System), and is a process of performing bit operation on color values of a graphic overlapping the same area for each RGB color. 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. 8C). 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 the case where processing conditions are set only for the source data to be rendered, the source data (the data to be overlaid), and the destination data after rendering (the rendering destination Processing conditions may be 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. 8C) 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. 8C).
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 destination color 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 bytes (32 bits) 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.

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. 10 is a conceptual diagram illustrating the relationship between band data and page data in banding processing. In the banding process, when the controller 10 cannot secure the 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. 10, 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 the intermediate data necessary for the drawing process, the multi-value drawing unit 115 executes the drawing process by accessing the memory in band units and storing the acquired intermediate data in the secured band memory. To do. Band data other than intermediate data that can be stored in the band memory is compressed or saved in a hard disk (not shown) or the like. The band data waiting to be processed 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 based on a flowchart shown in FIG.
As shown in the flow of FIG. 11, when the banding operation is started, first, one band data is acquired from the band data band 0 to 6 of the page data to be rendered according to a predetermined order (step S101).
Next, the drawing target pixels in the acquired band data are designated dot-sequentially (step S102), and the Gstatus (graphics state) of intermediate data for the designated pixels is obtained (step S103).
Next, the color value included in the Gstatus of the designated pixel is checked to determine whether the color value is monochrome or color (step S104).

If it is determined from the color value checked in step S104 that the pixel is color (step S104-NO), the RGB or CMYK color value is written in the PRGB format (4 bytes) on the color plane of the band memory. (Step S105).
On the other hand, if it is determined from the color value that the pixel is monochrome (step S104-YES), the density value is written in the monochrome format (1 byte) on the color plane of the band memory (step S106).
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 S107).
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 S108).

After the pixel data is drawn for the pixel specified in step S102, it is confirmed whether or not the drawing process for all the pixels in the current band has been completed (step S109).
If there is an unprocessed pixel in the current band (step S09-NO), the process returns to step S102, the next pixel is designated dot-sequentially, and the rendering process is performed as described above.
On the other hand, when the drawing processing for all pixels in the current band is completed (step S109-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 S109). S110). 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 S101 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 S111).
If there is unprocessed band data in the page data to be rendered (step S111-NO), the process returns to step S101, the next band data is acquired, and rendering processing is performed in the same manner as described above.
On the other hand, when the drawing process for all the band data of the page data to be drawn is completed (step S111-YES), the 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 and BG / UCR (Black generation and Under Color remova1) processing and converts the device into 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.
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, the BG / UCR process is performed on the 8-bit pixel data of each RGB color of the PRGB color plane obtained by the multi-value rendering process. 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.

At the final stage of the processing of the drawing core module 110, the multivalued CMYK data processed by the color conversion unit 116 is converted 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.

  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 CMYK binary conversion unit 120 PDL parser unit

Japanese Patent Laid-Open No. 2004-24369

Claims (12)

Intermediate data storage means for storing intermediate data including intermediate format image data obtained by analyzing the page description language in a state where the drawing object can be identified, and a plane representing color values from the intermediate data stored in the intermediate data storage means And a multi-value rendering means for rendering pixel data composed of an attribute plane of a pixel including a rendering object as an attribute, a color conversion means for performing color conversion for each object based on the pixel data rendered by the multi-value rendering means, and color An image forming apparatus having gradation processing means for gradation-converting image data converted by the conversion means,
The intermediate data storage means stores parameters used for translucent rendering processing as intermediate data,
The multi-value rendering unit adds a plane representing a parameter used for the translucent rendering process to the pixel data rendered from the intermediate data stored by the intermediate data storage unit, and stores the pixel data of each rendered plane. An image forming apparatus characterized in that an attribute plane of the drawn pixel and a plane representing a parameter used for translucent drawing processing are stored together. The image forming apparatus according to claim 1,
An image forming apparatus, wherein the plane representing the color value drawn by the multi-value drawing means is data arranged in a dot-sequential manner consisting of 4 bytes per pixel. The image forming apparatus according to claim 1,
An image forming apparatus according to claim 1, wherein the plane representing the color value drawn by the multi-value drawing means is data arranged in a dot-sequential manner consisting of 1 byte per pixel in the case of gray. The image forming apparatus according to claim 2,
In the case of a color space consisting of three channels, the plane representing the color values drawn by the multi-value drawing means uses the first byte for padding data and the second to fourth bytes for each color component data. An image forming apparatus. The image forming apparatus according to claim 1,
The attribute plane of the pixels drawn by the multi-value drawing unit and collectively saved and the plane representing the parameters used for the semi-transparent drawing process are data arranged in a dot sequence consisting of 2 bytes per pixel. Image forming apparatus. The image forming apparatus according to claim 1,
An image forming apparatus, wherein an attribute plane of a pixel drawn by the multi-value drawing unit and a plane representing a parameter used for a translucent drawing process are independent planes. The image forming apparatus according to claim 5, wherein:
The multi-value rendering unit assigns 8 bits or more to an attribute plane of a pixel to be rendered. The image forming apparatus according to any one of claims 1 to 7,
The image forming apparatus according to claim 1, wherein the multi-value rendering unit adapts the format of a plane representing a color value for each band in a banding operation. The image forming apparatus according to any one of claims 1 to 8,
A semi-transparent drawing process determination unit for determining whether or not there is a parameter used for the semi-transparent drawing process in the intermediate data stored in the intermediate data storage unit;
When the multi-value rendering unit determines that there is no translucent rendering process by the semi-transparent rendering process determination unit, the multi-value rendering unit represents the multi-value as a color value in a CMYK binary format as a plane representing the color value. An image forming apparatus. A process for analyzing intermediate format image data from the page description language, an intermediate data storage process for storing the intermediate data including the analyzed intermediate format image data in a state where the drawing object can be identified, and an intermediate data storage process From the intermediate data, a multi-value drawing process that draws pixel data consisting of a pixel value plane that includes a plane representing a color value and a drawing object as an attribute, and a color for each object based on the pixel data drawn in the multi-value drawing process An image data processing method including a color conversion step for performing conversion, and a gradation processing step for performing gradation conversion on the image data converted in the color conversion step,
The intermediate data storage step stores parameters used for the translucent rendering process as intermediate data,
The multi-value rendering step adds a plane representing parameters used for the translucent rendering process to the pixel data to be rendered from the intermediate data stored in the intermediate data storage step, and stores the pixel data of each rendered plane An image data processing method characterized in that an attribute plane of the drawn pixel and a parameter used for the translucent drawing process are stored together.   The program for making a computer perform each process of the image data processing method described in Claim 10. A computer-readable recording medium on which the program according to claim 11 is recorded.

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