JP2012071544A - Image forming apparatus and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus and image processing method, which can reduce waiting time of a drawing processing part and effectively print by a plurality of cores in the image forming apparatus having the plurality of cores.SOLUTION: The image forming apparatus 200 in which a drawing processing means 16 performs drawing processing by a region of a page includes: a print data storing means 13 for storing print data; a drawing instruction generating means 12 for analyzing the print data to generate drawing instruction data in which a drawing instruction of an object serving as a drawing object is described in each page; an optimization information creating means 14 for analyzing the print data in parallel with the drawing instruction generating means to create optimization information for determining a region taken by the drawing processing means 16; an intermediate data storing means 15 for storing the drawing instruction data and the optimization information; and the drawing processing means 16 for determining the region to be taken based on the optimization information to perform drawing processing of the drawing instruction data for each region.

Description

  The present invention relates to an image forming apparatus for visualizing print data, and more particularly to an image forming apparatus and an image processing method for processing print data using a multi-core or a plurality of CPUs.

  Conventionally, single-core CPUs have been used in many embedded devices, but as multi-core CPUs with multiple cores, such as dual-core and quad-core, have become popular in general-purpose PCs, their introduction has been promoted in embedded devices. It has been.

  However, just because the number of cores is doubled, the performance is not necessarily doubled, and the degree of influence depends on the algorithm and the like. In other words, in order to maximize the performance of the multi-core, it is necessary to appropriately distribute the processing to each core and execute the processing in parallel, so that no "wait" occurs in each core. A performance close to twice can be obtained. However, in general, it is rare that each processing can be executed in parallel (processing that doubles the performance), and how to parallelize the processing becomes a technical problem.

  A printer controller that analyzes PDL data and renders a drawing target is also considered to include a multi-core CPU. When the printer controller prints using a plurality of cores (processors), one is assigned to the “PDL analysis unit” that generates intermediate data, and the rest is assigned to the “drawing processing unit” that performs rendering based on the intermediate data. A technique has been devised in which the amount of processing allocated to the drawing processing unit is averaged so that no waiting occurs in the drawing processing unit (see, for example, Patent Document 1).

  In Patent Document 1, for the purpose of making the load on a plurality of drawing processing units uniform and improving the efficiency of printing performance, the drawing load is calculated from the area of the object processed in each drawing region, and each drawing process is performed. A drawing processing apparatus is disclosed in which the size of a drawing area is determined and assigned so that the load on the part is uniform.

  However, in Patent Document 1, a page is divided into a plurality of regions by the PDL analysis unit, and the processing amount is calculated from the area of the drawing object existing in each region. For this reason, the drawing processing unit cannot wait until the processing of the PDL analysis unit is finished, and the drawing processing unit is in a waiting state, and there is a problem that each core and CPU cannot be used effectively.

  Moreover, in patent document 1, since the area | region is divided | segmented on the basis of only the processing amount, there exists a problem that the optimal allocation according to the characteristic of each drawing process part cannot be performed.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention reduces the standby time of a drawing processing unit of a printer controller equipped with a plurality of cores or CPUs, and can efficiently print using the plurality of cores. An object is to provide a processing method.

  In view of the above-described problems, the present invention is an image forming apparatus in which a drawing processing unit performs drawing processing for each region of a page, and print data storage unit that stores print data, and the print data is analyzed to be a drawing target. A drawing command generation unit that generates drawing command data describing a drawing command of an object for each page; and the print data is analyzed in parallel with the drawing command generation unit to determine the area that the drawing processing unit is responsible for. Optimized information creating means for creating optimization information, intermediate data storage means for storing the drawing command data and the optimized information, and a region to be handled based on the optimized information are determined, and the drawing is performed for each region. And a drawing processing means for drawing the command data.

  It is possible to provide an image forming apparatus and an image processing method capable of reducing the waiting time of a drawing processing unit of a printer controller equipped with a plurality of cores or CPUs and efficiently printing with the plurality of cores.

It is an example of the figure which illustrates the rendering process of this embodiment typically. 1 is a diagram illustrating an example of a printing system. 2 is an example of a hardware configuration diagram of an MFP. FIG. It is an example of the figure which illustrates the function of a controller typically. It is a figure which shows an example of the functional block diagram of a PDL part. It is a figure which shows the example of a format of a PDF (Portable Document Format) file. It is a figure which shows an example of intermediate data. It is an example of the figure which shows typically the internal procedure of the process of a PDL part. It is an example of the figure explaining an example of the bounding box in a vector graphic. It is a figure which shows an example of the optimization value and the load value calculated from there. It is a figure which shows an example of the flowchart figure which shows the procedure in which an optimization information preparation part calculates a load value from optimization information. It is an example of the flowchart figure which shows the preparation procedure of optimization information. It is an example of the flowchart figure which shows the preparation procedure of a display list. It is an example of the flowchart figure which shows the procedure of rendering. It is a figure which shows another example of calculation of a load value. It is an example of a timing chart figure. It is another example of a timing chart figure. It is a figure which shows an example of the page in which the object for every area | region was biased. It is an example of the flowchart figure which shows the procedure which determines the area | region where each core performs rendering. It is an example of a table in which renderings that are good and impossible for each core are registered.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is an example of a diagram for schematically explaining the rendering processing of the present embodiment. For example, assuming that there are four cores, each core shares processing as follows.
Core 1: PDL analysis (creation of display list)
Core 2: Creation of optimization information → Rendering core 3: Rendering core 4: Rendering In other words, by assigning PDL analysis and creation of optimization information to different cores, these two processes are executed in parallel in time. This is one of the features. The optimization information is rendering load values or information for obtaining load values.

  Then, since the core 1 does not need to create optimization information, only PDL analysis, which is a relatively heavy process, can be completed in a shorter time than before. In addition, since the core 2 only needs to create optimization information that is a relatively light process, optimization information for a plurality of pages can be created while the core 1 performs PDL analysis for one page.

  As a result, the waiting time of the cores 3 and 4 to be rendered can be shortened to the time until the core 1 performs PDL analysis for one page. That is, since the PDL analysis unit has also created optimization information, the processing time is longer than the cores 3 and 4 to be rendered need to wait until the creation of PDL analysis + optimization information is completed. Can be shortened.

〔Constitution〕
FIG. 2 is a diagram illustrating an example of the printing system 300. A host PC (Personal Computer) 150 and an MFP (Multi Function Peripheral) 200 are connected via a network.

  The host PC 150 receives a user operation, and for example, some application program requests the OS graphic control unit (for example, GDI) to print document data. The graphic control unit generates a drawing command (intermediate file) for drawing document data using an API (basic function) that does not depend on the application.

  Thereafter, the graphic control unit calls a printer driver that generates PDL data corresponding to the MFP 200. An interface called DDI (Device Driver Interface) is defined between the graphic control unit and the printer driver. The printer driver converts the intermediate file into PDL data that can be interpreted by the printer, and transmits the PDL data to the MFP 200.

  As the PDL data, formats such as PostScript, PCL, RPCS, PDF (Portable Document Format), or XPS are known, and the format of the PDL data needs to be a format that the MFP 200 can analyze.

  The MFP 200 creates a display list and optimization information from the PDL data, performs drawing processing (rendering processing), etc., and prints it. The MFP 200 only needs to have a printer function, but may have a copier, a scanner, a transmission function (FAX, electronic mail, folder), and the like.

  FIG. 3 is an example of a hardware configuration diagram of the MFP 200. The MFP 200 includes a controller 100 that controls the entire MFP 200, an engine 160 that prints an image on a sheet, and a panel device 170 that displays an operation panel and a state that a user inputs.

  The controller 100 has a CPU 110, ROM 120, RAM 130, NVRAM 140, network I / F 151, engine I / F 161, panel I / F 171, and HDD 180.

  The CPU 110 is a multi-core CPU having a first core 111, a second core 112, a third core 113, and a fourth core 114, and executes instructions described in the program 181. The program 181 may be divided into four dedicated to each of the first core 111, the second core 112, the third core 113, and the fourth core 114, and four cores overlap one program. May be executed. The number of cores of the CPU 110 may be 5 or more as long as it is 2 or more. Further, instead of the multi-core type, a plurality of independent CPUs called multi-processors or multi-CPUs may be mounted.

  The ROM 120 stores a startup program, initial setting values, and the like. The RAM 130 is used as a work memory necessary for the operation of the page memory and software created by the controller 100. The NVRAM 140 is a non-volatile memory that stores printing conditions set in the MFP 200. The network I / F 151 transmits / receives data to / from the host PC 150 connected on the network. The engine I / F 161 controls the engine 160 by issuing a print instruction or the like.

  The engine 160 has at least a plotter engine that performs image formation. The plotter engine has, for example, a tandem type photosensitive drum, modulates a laser beam based on image data obtained by rendering PDL data received from the host PC 150, and scans the photosensitive drum to form a latent image. Then, the toner image for each page developed by attaching the toner to the latent image is transferred to the sheet with heat and pressure. The plotter engine may be an ink jet type. The engine 160 includes a scanner engine and a FAX engine.

  The panel I / F 171 controls input / output with the panel device 170. The HDD 180 stores font data and programs 181.

  FIG. 4 is an example of a diagram for schematically explaining the function of the controller 100. 4, the same parts as those in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted. The functions of the controller 100 are represented by the printer control system 204 and the PDL unit 205 that are realized by the CPU 110 executing the program 181.

  A PDL unit 205 receives PDL data from the printer control system 204 and creates a print image. The PDL unit 205 corresponds to PostScript PCL, RPCS, PDF, XPS, etc. as the format of PDL data.

  The printer control system 204 controls the printing procedure, such as requesting rendering to the PDL unit 205 and then requesting printing to the engine I / F 206 in order to print the PDL data received by the network I / F 202.

  FIG. 5 is a diagram illustrating an example of a functional block diagram of the PDL unit 205. The PDL unit 205 includes an input data reception unit 11, a DL creation unit 12, an optimization information creation unit 14, a plurality of drawing processing units 16, a PDL data storage unit 13, and an intermediate data storage unit 15. The PDL data storage unit 13 and the intermediate data storage unit 15 have the HDD 180 and the RAM 130 as entities.

  The input data receiving unit 11 stores the PDL data received from the host PC 150 by the network I / F 151 in the PDL data storage unit 13. The DL creation unit 12 parses the PDL data, extracts objects (text, images, vector graphics, etc.) included in the PDL data, and displays a display list (intermediate) based on this and drawing information included in the PDL data. Data). The display list is stored in the intermediate data storage unit 15.

  The optimization information creation unit 14 creates optimization information from PDL data based on characteristics such as arrangement information and types of various objects to be drawn. This optimization information is also stored in the intermediate data storage unit 15. Although the optimization information will be described later, the optimization information is information for determining the drawing processing means 16 that renders the object (or the drawing area including the object). More specifically, it is information for determining the processing load for drawing an object, or the processing load itself.

  The drawing processing unit 16 determines a drawing area in charge of drawing based on the display list and optimization information stored in the intermediate data storage unit 15, and renders output image data based on the display list for each drawing area. The drawing area is a range on the page obtained by dividing the page in the longitudinal direction at equal intervals or predetermined intervals, and is known to the optimization information creation unit 14 and the drawing processing unit 16.

  The drawing processing unit 16 shown in the figure is three because the number of cores of the CPU 110 is taken into consideration. In this embodiment, one of the four cores is created in the DL creation unit 12 and one of the four cores is created in the optimized information. The rest is assigned to the unit 14 and the drawing processing unit 16 is assigned to the rest. The optimization information creation unit 14 also operates as the drawing processing unit 16. For this reason, there are three drawing processing units 16 in the figure.

[About PDL data, etc.]
FIG. 6 is a diagram illustrating a format example of a PDF (Portable Document Format) file. Here, a PDF file is used to explain the PDL data.

The PDF file is composed of a header, a body, a cross reference table, and a trailer. In the header, one line including the version information of the PDF is described to indicate that the file format is PDF (for example, “% PDF-1.4”).
In the body, the body of data constituting a page such as text or image is described as an object. Each object is given an identification number, and each object is described in an arbitrary order in the body regardless of the page order of the displayed document.
Object number Generation number (usually zero) obj
<<
/ Type / Page
/ Parent Object number Generation number R
/ Contents Object number n Generation number R
>>
endobj
Since all the documents, pages, graphics and characters in a page are handled as objects in PDF, object numbers are assigned to all. In this example, the object number in the Parent line indicates the object number of the parent page of this page. “R” is a symbol meaning that this page refers to.

  The object number n in the Contents line indicates the object number of the object (described in this page) in the page.

  Assume that the Contents object describes the object number n as follows (the description not used in the explanation is omitted).

Object number n Generation number obj
<<
/ Length number of bytes
>>
stream
…… The drawing command enters here ……
endstream
endobj
Length represents the size (number of bytes) of the object specified by stream to endstream. For example, in the case of a character, an instruction such as “font identification information, font size, first character coordinate system designation character string” is described in a range surrounded by “BT to ET”.

  In the case of vector graphics, a command such as “designation of coordinate system color specification, coordinate + movement command, coordinate + line drawing command, coordinate + curve drawing command,...” Is described in a range surrounded by “q to Q”.

  In the case of an image, it is described in the format surrounded by “BI to EI” in the format of “size, encoding method ID (Image Data)”.

  In the cross reference table, position information in the file of the object described in the body is described as an offset. That is, the number of bytes from the top of the file to the top of the data of each object is described. Thus, the description position of the body has nothing to do with the position on the page.

  In the trailer, an object (catalog object) indicating the top of the document structure is designated by an object number with the / Root attribute. Thereafter, the position of each object is determined by the description of the body and the cross reference table.

  As described above, since objects are arranged in an arbitrary order in the PDF file regardless of the page order of the displayed document, the controller 100 determines the contents of the trailer when accessing each object. It becomes possible only by referring / analyzing and referring / analyzing the contents of the cross-reference table based on the result. That is, in the standard PDF file, the trailer to be referred to and the cross-reference table are described at the end of the file, that is, after the body (data body), so the DL creation unit 12 and the optimization information creation unit 14 It is necessary to start processing after the entire PDF file is transferred and stored in a storage medium such as the HDD 180.

  FIG. 7 is a diagram illustrating an example of a display list. The display list is a data format that can be processed by each drawing processing unit 16, and is a list of various drawing commands and setting information. For example, “set foreground color (R, G, B)” is a command for instructing the foreground color, “set raster operation (Op Code)” is a command for instructing an operation to be performed on the image, and “draw rectangle (x, y, w, h) "are rectangular drawing commands.

  The display list created by the DL creation unit 12 is stored in the intermediate data storage unit 15, and is sequentially interpreted by the drawing processing unit 16, and when there is an object to be drawn in the assigned drawing area, rendering is performed in the drawing area. I do.

[Processing contents of PDL part]
FIG. 8 is an example of a diagram schematically showing an internal procedure of processing of the PDL unit 205.
(1) The input data receiving unit 11 receives an input of PDF.
PDL data such as PCL and PS can be read, analyzed, and rendered by the DL creation unit 12 in order from the top.
(2) On the other hand, in the PDL data such as PDF and XPS, since the head position of the data to be analyzed is attached to the latter half of the input data (cross reference table, trailer), the input data receiving unit 11 is the PDL data storage unit. 13 needs to temporarily store the PDL data.
(3) However, the PDL data stored in the PDL data storage unit 13 can be accessed not only by sequential access from the beginning or random access at a desired location, but also by a plurality of processing means.

Therefore, if a multi-core environment is used, the DL creation unit 12 is assigned to the first core 111 and PDL data is analyzed to create a display list serving as intermediate data, while the optimization information creation unit 14 is provided to the second core 112. Parallel processing such as analyzing allocation PDL data and creating optimization information becomes possible.
(4) If two pieces of information such as display list / optimization information are created at the same time, the processing time required for analyzing the PDL data is the longer one of the display list / optimization information. However, the creation of optimization information does not strictly analyze the PDL data, but reads processing load information and area from the type of drawing object, or the size of a bounding box (drawing area surrounding the entire object) described later. This is a process that is sufficiently lighter than creating a display list. Therefore, the optimization information for one page is created earlier than the display list for at least one page is created.
(5) The third core 113 and the fourth core 114 are assigned to the drawing processing unit 16, and the two drawing processing units 16 select the drawing area (Band) to be drawn with reference to the optimization information.
(6) The rendering processing unit 16 performs rendering by referring to and analyzing the display list.

  Originally, if a part of the display list is created, the drawing processing unit 16 can start the drawing process without creating a display list for one page. In this case, when the drawing processing unit 16 waits until the creation of the optimization information, the processing speed may decrease.

  FIG. 9A is a diagram illustrating an example of a timing chart of creation of a display list for the first page, creation of optimization information, and drawing processing. Before the creation of the display list (Parsar1) is completed, the drawing processing units (renderer 1-1, renderer 1-2) have started drawing processing. However, the optimization information creation unit 14 (optimization Md) completes the creation of the optimization information (OP1) after the drawing processing unit 14 starts the drawing process. Therefore, the allocation of the drawing area by the optimization information is not in time for the first page.

  For this reason, in the present embodiment, the optimization information creation unit 14 does not create optimization information for the first page, the drawing processing unit 16 takes charge of the drawing areas in order from the top, and the optimization information for the next and subsequent pages. It may be preferable to assign a drawing area using. Therefore, in this case, if the document has only one page, the optimization information creation unit 14 does not create optimization information.

  Even if the drawing processing unit 16 starts drawing processing before the creation of the display list is completed, the drawing processing unit 16 can reassign each drawing region as soon as the creation of the optimization information is completed. Therefore, it cannot be said that it is most preferable not to always create the optimization information for the first page, and an optimal processing procedure may be adopted depending on the function of the drawing processing unit.

Next, the bounding box will be described.
FIG. 9B is an example of a diagram for explaining an example of a bounding box in vector graphics. Here, a cubic Bezier curve will be described as an example of vector graphics. P0 and P3 are end points of the Bezier curve, and P1 and P2 are direction points. A line connecting P1 and P0 becomes a vector graphic tangent passing through P0, and a line connecting P2 and P3 becomes a vector graphic tangent passing through P3. The curves P0 to P3 are determined by the coordinates of the four points P0 to P3 and the Bezier curve formula.

  Therefore, even if the curve is obtained immediately, calculating the area is heavy. Therefore, when the object is a vector graphic of a character or a complicated shape, the drawing processing unit 16 does not accurately calculate the drawing area, and draws this size using a circumscribed rectangle including all start points, end points, and control points as a vector graphic box. Substituting an area can greatly reduce the amount of calculation.

[Optimization information]
FIG. 10A is a diagram illustrating an example of optimization information and a load value calculated from the optimization information. The optimization information includes, for example, the object type and drawing area, or a load value for drawing the object calculated from these (may include both).

  The display list lists drawing commands for various objects (text, images, vector graphics), but the contents processed by the drawing processing unit 16 vary greatly depending on the type of object.

  In the present embodiment, among the processes that differ depending on the type of object, the magnitude of the load is important. Therefore, the optimization information includes a calculation cost necessary for rendering each drawing object.

  The optimization information creation unit 14 not only provides the types of drawing objects (text, image, vector graphics), but also those that have greatly different drawing processing loads such as RGB color images and monochrome images. deal with.

  In addition, the drawing area can be easily calculated if it is an image or a vector graphic such as a rectangle or a circle, but a vector graphic such as a Bezier curve requires a load to calculate the area from a set of control points ( Conversion from vector data to raster data (scanline conversion) is required, which increases processing costs.) Instead of an accurate drawing area, the size of the bounding box is used instead of the drawing area.

  FIG. 11 is an example of a flowchart illustrating a procedure for the optimization information creation unit 14 to calculate a load value from the optimization information. The drawing processing unit 16 may calculate instead of the optimization information creating unit 14.

  The optimization information creation unit 14 calculates the load value of each drawing area using the load index shown in FIG. The load index is a weight based on an ability value when the drawing processing unit 16 processes an object, and a larger value is determined as the load increases for each type of object. For example, the graphic is “1” and the character is “0.5”. The relationship between the load index and the object is stored by the optimization information creating unit 14 describing it in a part of the code.

  The optimization information creation unit 14 first determines the type of object in a certain drawing area (S110). The type of object is clear from the display list.

  The optimization information creation unit 14 reads the load index of the object (S120).

  Next, the optimization information creation unit 14 determines whether or not the object is a vector graphic that needs to be converted to a scan line (S130). Whether or not the vector graphic needs to be converted into a scan line is determined based on, for example, whether or not it includes a curved portion.

  In the case of a vector graphic that needs to be converted to a scan line, the optimization information creation unit 14 calculates the size of the bounding box (S140).

  In the case of a vector graphic that does not require conversion to a scan line, the optimization information creating unit 14 calculates the drawing area of the object (S150).

Then, the optimization information creating unit 14 calculates the load value of the object from the drawing area or bounding box size and the load index (S160).
An example of calculating the load value will be described below.

<Drawing area 1 (band1)>
An example of calculating the load value will be described with reference to FIG.
Graphic 1 is a circular vector graphic, graphic 2 is a rectangular vector graphic, and graphic 3 is a square (diamond) vector graphic.
Graphic 1: Drawing area 100, Load index: 1
Graphic 2: Drawing area 120, Load index: 1
Graphic 3: Drawing area 150, Load index: 1
Load value of graphic 1: 100
Load value of graphic 2: 120
Load value of graphic 3: 150
<Drawing area 2 (band2)>
Characters are vector graphics that need to be converted to scanlines.
Character 1: Bounding box size 100, Load index: 0.5
Character 2: Bounding box size 130, Load index: 0.5
Character 3: Bounding box size 80, Load index: 0.5
Load value of character 1: 50
Load value of character 2: 65
Load value of character 3: 40
<Drawing area 4 (band4)>
Image 1 is image data in RGB full color.
Image 1: Drawing area 500, Load index: 3
Load value of image 1: 1500
The drawing processing unit 16 adds the load values of the objects for each drawing area to obtain the load value of the drawing area. Then, the drawing processing unit 16 sets rendering processing targets in order from the drawing region having the largest load value. If the rendering process is started first from a drawing area with a large load value, there is a high possibility that the maximum time required for processing one page can be suppressed.

  In the procedure of FIG. 14 (drawing area allocation process) to be described later, the drawing processing unit 16 determines the drawing area having the largest load value from among the unprocessed drawing areas. Since each drawing processing unit 16 repeats this, the overall processing time of one page can be shortened.

[Operation procedure]
FIG. 12 is an example of a flowchart showing a procedure for creating optimization information.

The optimization information creation unit 14 reads the PDF stored in the PDL data storage unit 13 (S210).
The optimization information creation unit 14 determines whether or not a plurality of pages are included in the PDL data (S
220).

  When a plurality of pages are not included (No in S220), only one page is obtained, but since the allocation of the drawing area by the optimization information is not in time, the processing in FIG. 10 ends without creating the optimization information.

  When multiple pages are included (Yes in S220), the optimization information creation unit 14 creates optimization information for the second and subsequent pages based on the procedure of FIG. 11 (S230). That is, the type of each drawing object is specified for each drawing area, the drawing area is calculated, and the load value is further calculated.

  FIG. 13 is an example of a flowchart showing a display list creation procedure.

The DL creation unit 12 reads the PDF stored in the PDL data storage unit 13 (S310).
The DL creation unit 12 analyzes the body part object based on the PDF cross-reference table and the trailer, and creates a display list (S320).

  The DL creation unit 12 determines whether or not the display list has been created up to the end of the PDF (S330).

FIG. 14 is an example of a flowchart illustrating a rendering procedure.
The drawing processing unit 16 divides and renders one page into a plurality of drawing areas. Since the plurality of drawing processing units 16 efficiently render one page, which drawing processing unit 16 renders for each drawing area. Decide what to do.

  First, the drawing processing unit 16 determines whether or not there is an undrawn area for each page (S410). If there is no undrawn area (No in S410), the processing for the page ends.

  If there is an undrawn area (Yes in S410), the drawing processing unit 16 determines whether there is optimization information for the page (S420). That is, if there is only one undrawn area, it is sufficient to assign that one drawing area to itself, but if there are a plurality of undrawn areas, it is necessary to determine which drawing area is responsible for rendering based on optimization information.

  Therefore, when the optimization information is generated (Yes in S420), the drawing processing unit 16 refers to the optimization information and assigns the drawing area in charge to itself (S430). For example, the drawing area with the highest load value is set as the processing target.

  If the optimization information has not been generated (No in S420), the drawing processing unit 16 assigns the drawing area in charge to itself in order from the determined location of the drawing area (S440). For example, allocation is performed in a predetermined priority order from the top of the page, near the center of the page, or the like.

  When the drawing area is allocated, the drawing processing unit 16 performs rendering by referring to the display list of the drawing area (S450).

〔Concrete example〕
FIG. 15 is a diagram illustrating another example of load value calculation. In FIG. 15, the object straddles the drawing area, but the basic idea is the same. An object straddling the drawing area is divided by the drawing processing unit 16 at the boundary between the drawing area and the drawing area.

  The graphic 4 is a circular vector graphic. The upper side divided by the boundary is a graphic 4U, and the lower side is a graphic 4D. The area when a circular graphic is divided by a straight line is previously held in a table or the like as a function of the shortest distance between the straight line and the circumference, for example. By doing so, the processing load can be suppressed.

  The image 2 is RGB full-color image data, and the upper side divided by the boundary is an image 2U and the lower side is an image 2D. The area when the rectangular drawing area is divided by a straight line is obtained by the ratio from the upper side to the boundary with respect to the height of the image.

  For the characters 4 to 6, the size of the bounding box is required instead of the drawing area. The upper side divided at the boundary of the character 4 is the character 4U, the lower side is 4D, the upper side divided at the boundary of the character 5 is the character 5U, the lower side is 5D, the upper side divided at the boundary of the character 6 is the character 6U, the lower side Let the side be 6D.

  Since the bounding box is rectangular, the area when the size of the bounding box is divided by a straight line is obtained by the ratio from the upper side to the boundary with respect to the height of the bounding box.

<Drawing area 1 (band1)>
Graphic 4U: drawing area 50, load index: 1
Load value: 50
<Drawing area 2 (band2)>
Graphic 4D: drawing area 70, load index: 1
Image 2U: drawing area 120, load index: 3
Load value: 70 × 1 + 120 × 3 = 430
<Drawing area 3 (band 3)>
Image 2D: drawing area 120, load index: 1
Character 4U: Bounding box size 70, Load index: 0.5
Character 5U: Bounding box size 91, Load index: 0.5
Character 6U: Bounding box size 56, Load index: 0.5
Load value: 120 × 1 + 70 × 0.5 + 91 × 0.5 + 56 × 0.5 = 229
<Drawing area 4 (band4)>
Character 4D: Bounding box size 30, Load index: 0.5
Character 5D: Bounding box size 39, Load index: 0.5
Character 6D: Bounding box size 24, Load index: 0.5
Load value: 30 × 0.5 + 39 × 0.5 + 24 × 0.5 = 46.5
The drawing processing unit 16 is responsible for drawing in the order of Band2->Band3->Band1-> Band4 in descending order of load value.

[Timing chart (effect)]
FIG. 16 shows an example of a timing chart. For comparison, FIG. 16A shows a timing chart of the conventional configuration, and FIG. 16B shows a timing chart of the configuration of the present embodiment.

  In the conventional configuration, the first core 111 is generally assigned to an interpreter (PDL analysis unit), and the second core 112 to the fourth core 114 are assigned to a renderer (drawing processing unit 16). For this reason, the first core 111 is responsible for Parser (display list generation) and Op (load information generation).

  When the first core 111 creates a display list for the first page, load information is also accumulated. For this reason, the renderers of the second to fourth cores have to wait until the first core 111 creates the display list and load information for each page. As shown in the figure, when the first core 111 creates the display list and load information for the first page, the second to fourth cores are waiting, and the first core 111 stores the display list and load information for the second page. At the time of creation, the second to fourth cores process the rendering of the first page for each drawing area. Further, in order for the second to fourth cores to render the third page for each drawing area, the first core 111 must create the display list and load information for the third page.

  On the other hand, in the PDL unit 205 of the present embodiment, the first core 111 is responsible only for interpreter (PDL analysis), and the second core 112 is responsible only for creating optimization information. The creation of the optimization information itself is completed in a relatively short time. For this reason, while the first core 111 creates a display list for one page, the creation of optimization information proceeds considerably.

  Further, since the first core 111 only performs PDL analysis, the processing time of each page can be shortened by the amount that the optimization information is not created.

  Therefore, the third core 113 and the fourth core 114 can start rendering earlier than before. In addition, since the creation of the optimization information for the second core 112 is completed in a relatively short time, even if the second core 112 is to create the optimization information, the optimization information is created early and rendered. Can take charge. From the above, it can be seen that the processing time of the previous page can be shortened by the short standby time of the second to fourth cores.

  In FIG. 16B, optimization information for the first page is created. For example, when the drawing processing unit 14 does not perform drawing processing until a display list for one page is created, optimization information for the first page is created by creating optimization information for the first page as shown in the figure. The print processing time can be shortened as much as the optimization information can be used rather than the case where the information is not created.

  When the drawing processing unit 14 starts the drawing process before the display list for one page is created, the optimization information creating unit 14 does not create the optimization information for the first page. For this reason, the second core starts with the creation of optimization information (Op2) for the first page, and the third and fourth cores start drawing processing in the middle of the creation of the display list for the first page. Therefore, it is possible to shorten the print processing time as compared with the case of creating optimization information for the first page.

  FIG. 17 shows another example of a timing chart of this embodiment. Since the creation of the optimization information executed by the second core 112 is completed in a relatively short time, there is a possibility that inconvenience may occur when the number of pages is large.

  That is, the optimization information created by the optimization information creation unit 14 is stored in the intermediate data storage unit 15. However, if the number of pages is large, only optimization information is created compared to creation and rendering of a display list. As a result, the intermediate data storage unit 15 is consumed.

  The optimization information of the rendered drawing area becomes unnecessary and is deleted. However, when the number of pages is large, a lot of optimization information is created first, and a lot of memory is consumed.

  Therefore, when the number of pages of PDL data to be printed is equal to or greater than the threshold, the second core 112 takes charge of drawing processing after creating optimization information for a specific number of pages.

  In FIG. 17, the second core 112 has started rendering after creating optimization information Op1 to Op5 for five pages. By doing so, it is possible to prevent the optimization information from consuming the memory when the number of pages of PDL data is large.

  In addition, when the number of created optimization information or the number of pages is equal to or less than a predetermined value (for example, 2), the second core 112 starts creating optimization information for a specific number of pages again. In this way, the second core 112 can preferentially create optimization information and perform rendering without consuming too much capacity of the intermediate data storage unit 15.

[Modification]
Although the drawing processing unit 16 selects the drawing region in the order of increasing load value, the drawing processing unit 16 may have different processing times for the same processing. That is, for example, the third core 113 has a fast color rendering but a slow character rendering, and the fourth core 114 has the opposite characteristics.

  In this case, rendering the drawing area with the color image by the third core 113 and rendering the drawing area with many characters by the fourth core 114 leads to a reduction in the overall processing time.

  FIG. 18 shows an example of a page in which objects for each drawing area are biased. The drawing area 1 includes color image data, but the drawing areas 2 to 4 are all characters. In such a page, the drawing area 1 is preferably executed by a core having an instruction set suitable for color rendering. Therefore, the rendering time of the drawing area 1 can be shortened by the third core 113 preferentially rendering the drawing area 1.

  On the other hand, if a certain core is unable to render a specific object, the core can play without doing anything by letting the core process the drawing area that contains the object that the core can render. Can be prevented. Therefore, it is preferable to assign a process to be executed by the core according to a process that the core is good at.

  FIG. 19 is an example of a flowchart illustrating a procedure for determining a drawing area in which each core executes rendering. FIG. 20 is an example of a table in which renderings that are good and impossible for each core are registered. Such a table is registered in the PDL unit 205 in advance.

In FIG. 19, the processing up to step S420 is the same as that in FIG.
When there is an undrawn area (Yes in S410) and there is optimization information (Yes in S420), the drawing processing unit 16 performs processing registered in the table of FIG. 20 among the drawing areas with optimization information. It is determined whether there is a drawing area in which an object that cannot be processed exists (S421).

  If there is a drawing area with an object that cannot be processed, the drawing area is excluded from rendering targets, and the remaining drawing areas are made candidates for processing (S422).

  Next, the drawing processing unit 16 determines whether there is a drawing area in which an object that cannot be processed by another core exists in the undrawn area with reference to the table of FIG. 20 (S423).

  If there is a drawing area in which an object that cannot be processed by another core exists in the undrawn area (Yes in S423), there is a possibility that waiting may occur if the drawing area is left, so that the drawing area is set as a candidate for processing. (S424).

  Next, the drawing processing unit 16 determines whether there is a drawing area with an object that the core is good at processing among the candidates with reference to the table of FIG. 20 (S425). Thereby, the drawing processing unit 16 can identify an object whose rendering ends quickly (S426). For example, the rendering processing unit 16 that has a fast color image rendering process can preferentially target a rendering area that includes the object, and the rendering processing unit 16 that has a fast character rendering process can preferentially have that object. The included drawing area can be rendered.

  When there is no drawing area including an object that is good at processing (No in S425), the drawing processing unit 16 refers to the optimization information, and takes charge of the processing objects in order from the drawing area with the largest load value (S427). The subsequent processing is the same as in FIG.

  As described above, in the MFP 200 of this embodiment, the optimization information generation unit 14 creates optimization information in parallel with the DL analysis unit 12 in time, so that the wait between the DL analysis unit 12 and the drawing processing unit 16 is possible. Time is shortened. Further, if not only the optimization information but also the drawing processing that the drawing processing unit 16 is good at, the processing time per page can be further reduced.

100 controller 110 CPU
111 1st core 112 2nd core 113 3rd core 114 4th core 120 ROM
130 RAM
140 NVRAM
150 host PC
151 Network I / F
161 Engine I / F
171 Panel I / F
160 Engine 170 Panel device 180 HDD
200 MFP
204 Printer control system 205 PDL unit
300 printing system

Japanese Patent No. 3474078

Claims (10)

An image forming apparatus in which drawing processing means performs drawing processing for each area of a page,
Print data storage means for storing print data;
Drawing command generation means for analyzing the print data and generating drawing command data describing a drawing command of an object to be drawn for each page;
Analyzing the print data in parallel with the drawing command generating means, optimizing information creating means for creating optimization information for determining the area that the drawing processing means is responsible for;
Intermediate data storage means for storing the drawing command data and the optimization information;
The drawing processing means for determining a region to be served based on the optimization information and drawing the drawing command data for each region;
An image forming apparatus comprising: When the total number of pages is equal to or greater than a predetermined value, the optimization information creating unit creates the optimization information for each page having a predetermined number of pages less than the predetermined value, and then serves as the drawing processing unit for drawing the area. Drawing the command data,
When the number of pages in which the optimization information is stored in the intermediate data storage unit is equal to or less than a threshold, the print data is analyzed, and the creation of the optimization information is resumed.
The image forming apparatus according to claim 1. The optimization information creating means does not create the optimization information when the total number of pages is one page, and draws the drawing command data of the area as the drawing processing means;
The image forming apparatus according to claim 1. The optimization information creating means creates, as the optimization information, a load value that determines a processing load of drawing processing based on an object type and a drawing area for each region.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. When the object is a vector graphic, the optimization information creating unit obtains the drawing area of a circumscribed rectangle including all the control points of the vector graphic.
The image forming apparatus according to claim 4. A load index table in which the load index of the processing load is associated with an object type;
The optimization information creation means calculates the load value by multiplying the drawing area by the load index read from the load index table based on the type of object.
The image forming apparatus according to claim 4, wherein the image forming apparatus is an image forming apparatus. The drawing processing means has a processing target determination table that associates an appropriate object type as a drawing processing target,
The drawing processing means determines the region as a processing target when an object included in the unprocessed region is included in the processing target determination table.
The image forming apparatus according to claim 4, wherein the image forming apparatus is an image forming apparatus. The drawing processing means determines the region having the highest load value as a processing target when an object included in the unprocessed region is not included in the processing target determination table.
The image forming apparatus according to claim 4, wherein the image forming apparatus is an image forming apparatus. It has a multi-core type CPU or multiple CPUs,
One core or CPU for the drawing command generation means,
One core or CPU for the optimization information creation means,
The image forming apparatus according to claim 1, wherein a remaining core or CPU is assigned to the drawing processing unit, and each unit executes a process. An image processing method in which drawing processing means performs drawing processing for each area of a page,
A step in which the data acquisition means stores the print data acquired from the outside in the print data storage means;
A drawing command generation unit that analyzes the print data, generates a drawing command data describing a drawing command of an object to be drawn for each page, and stores the drawing command data in an intermediate data storage unit;
Optimization information creation means analyzes the print data in parallel with the drawing command generation means, creates optimization information for determining the area that the drawing processing means is responsible for, and stores it in the intermediate data storage means And steps to
The drawing processing means determining a region to be served based on the optimization information, and drawing the drawing command data for each region;
An image processing method comprising: