JP5936363B2 - Image processing apparatus and image processing method - Google Patents

Description

  The present invention relates to an electronic document print processing technique, and more particularly to an image processing apparatus and an image processing method for directly receiving an electronic document and performing a printing process.

  Due to recent diversification of application software and OS, print drawing commands have become complicated, and the load of drawing processing and image processing of the printing apparatus has increased. Currently, in order to process a complicated drawing command at a high speed, a drawing method using scan line rendering that writes a drawing result to an output memory in units of lines is used. The scan line rendering uses edge information generation means for extracting the outline of the object, level information generation means for determining the edge overlap of the object, and fill information generation means for designating the painting method inside the object. Further, the image processing apparatus includes a drawing unit that draws a foreground and a background by logical operation using image data in a process of performing scanline rendering on an object included in an electronic document and writing a drawing result to an output memory. There are two types of drawing methods that use this logical operation: “edge drawing” using edges or “mask drawing” using a mask.

  For example, when drawing Object1 (301) included in Page (300) as shown in FIG. 3, in “mask drawing”, paint information (303) and a mask image (304) in which the ROP function is specified are used. ,draw. The mask image (304) is composed of information indicating ON / OFF for each pixel. Then, a background (here, the background color of the page (white)) is selected at the OFF coordinate position. Also, an ROP instruction is given so that the color indicated by the paint information (303) is arranged at the ON coordinate position. Thus, the rendering of Object1 (301) is realized by ON / OFF for each coordinate.

  On the other hand, “edge drawing” is a method of drawing using the paint information (305) and the edge data (306). That is, as shown in FIG. 3, the edge data (306) is obtained by drawing the color indicated by the paint information (305) based on the information of the start point and the end point (arrows in FIG. 3), so that Object 1 (301). Realize drawing.

  Conventionally, in order to speed up drawing by this ROP instruction, it is known to analyze image data that is an input mask image and change the drawing method according to the result. For example, the calculation processing speed can be increased by selecting drawing using edges or drawing using a mask according to the number of edges included in the image data (see, for example, Patent Document 1). .) Alternatively, the image processing speed can be increased by analyzing the image data that is the mask image and considering the logical operation sequence and switching between the drawing method using the edge and the drawing method using the mask. It is known (for example, refer to Patent Document 2).

JP 2006-48172 A JP 2006-341376 A

  The image data analysis processing in the above-described prior art has a problem that when the size of the object is large, the number of pixels to be investigated is large, and thus the image data analysis processing itself is expensive. Therefore, in some electronic documents, when the size of the object is large, edge drawing is performed, and when the size of the object is small, mask drawing is performed to speed up the drawing process.

  However, depending on the configuration of the object of the electronic document, there are cases where high speed cannot be realized. For example, as shown in FIG. 4A, when the size of the object itself is small, but rendering the object overlapped in the same area, the processing speed may be significantly reduced. This is because when the mask drawing is performed on the overlapping area in this way, the cache area of the mask image used when rendering is performed in units of pixels is insufficient.

  Also, for example, as shown in FIG. 4B, the processing speed is significantly reduced even when the size of the object is large but the image data has a checkered pattern and the generated edge data is very large. Sometimes. As described above, when edge drawing is performed on the object, edge data used in processing executed in units of edges increases, and a cache area becomes insufficient.

In order to solve the above problems, an image processing apparatus according to the present invention includes: a drawing unit that draws an image; and a cache memory that is used when the drawing unit draws the image. Determination means for determining whether or not a predetermined space is available when drawing, wherein the drawing means draws the image by a drawing method determined based on a determination result by the determination means, The drawing method is based on mask drawing for drawing the image by determining whether the color of the pixel in the region corresponding to the image is the designated color or the background color for each pixel, or information indicating the outline of the image It is edge drawing which draws the said image by painting the inside of the outline of the said image with a designated color .

  According to the present invention, the processing speed in rendering processing is improved.

It is a block diagram which shows the structural example of the image processing apparatus which concerns on embodiment of this invention. It is a figure which shows the function structural example of the control apparatus which concerns on embodiment of this invention. It is a figure for demonstrating mask drawing and edge drawing. The figure which shows an example of the problem which should be solved in the prior art of mask drawing and edge drawing concerning this invention. It is a flowchart which shows the process sequence of the process which converts the mask drawing which concerns on Example 1 of this invention into edge drawing. It is the figure which showed typically a mode that it converts into edge drawing, when the image which concerns on mask drawing in Example 1 of this invention is input. It is a flowchart which shows the process sequence of the process which converts the edge drawing which concerns on Example 2 of this invention into mask drawing. It is the figure which showed typically the process which converts edge drawing in Example 2 of this invention into mask drawing. It is the figure which showed typically the process which converts the edge drawing which concerns on Example 2 of this invention into one mask drawing. It is a figure which shows an example of the effect of the invention in the Example of this invention.

  Examples according to the present invention will be described below. In the first embodiment, in the rendering processing unit (215), when the cache memory of the image cache storing the pixel-by-pixel investigation result is insufficient, the pixel-by-pixel investigation is switched to the edge position investigation. In the second embodiment, when the cache memory of the edge cache storing the edge position investigation result is insufficient, the edge position investigation is switched to the pixel unit investigation.

  The embodiment of the present invention is implemented by an image processing apparatus (100) having a configuration as shown in FIG. 1, for example, an MFP (Multi Function Printer). Of course, it goes without saying that a single function printer (SFP), a laser beam printer (LBP), or other printers may be used.

  FIG. 1 is a block diagram illustrating a configuration example of an image processing apparatus in which a controller as an electronic component according to an embodiment of the present invention is mounted.

  The image processing apparatus (100) can be connected to a host computer (191, 192) such as a PC via a LAN (Local Area Network) such as Ethernet (registered trademark). The image processing apparatus (100) includes a reader device (120), a printer device (130), an operation display unit (150), an image storage unit (160), and a control device (controller unit) that controls these components. ) (110).

  The control device (110) includes a CPU (112), a ROM (114), a RAM (116), and the like.

  The CPU (112) performs overall control of the entire image processing apparatus 100 based on a program stored in the ROM (114) or other storage medium. For example, the control device (110) loads programs for performing PDL interpretation processing, display list generation processing, rendering processing, and the like on the CPU (112). In addition, regarding rendering processing, a configuration using dedicated hardware may be used.

  The printer device (130) outputs image data.

  The operation / display unit (150) includes a keyboard for performing various print setting operations, an operation button for performing image output settings, and the like when performing image output processing.

  The image storage unit (160) can store / save print data such as image data, document data, and printing device control language (for example, ESC code, PDL (Page Description Language)). For example, the data storage unit (130) can store / save image data, documents, and PDL received from the host computer (191, 192) via the LAN, and image data read from the reader device (120). .

  FIG. 2 is a diagram illustrating an example of a functional configuration of a software module that operates in the control device (110) of the image processing device (100) according to the present invention.

  The job control unit (200) controls a print job input to output by means such as a function call or message communication.

  A plurality of PDL analysis units (201/202/203) can be provided according to the type of PDL (for example, PostScript, PCL, XPS, etc.) installed in the image processing apparatus (100).

  The PDL analysis unit (201/202/203) reads the PDL data stored in the PDL reception buffer and executes interpretation processing in accordance with an instruction from the job control unit (200).

  The display list generation unit (210) generates a display list based on the drawing information sent from the PDL analysis unit (201/202/203) in accordance with an instruction from the job control unit (200), and stores the generated display list in the memory. To store.

  The rendering processing unit (215) loads a display list from the memory, converts the display list into image data, and executes a rendering process for outputting to the memory.

  Specific examples of the present invention will be described below for the image processing apparatus having the above-described configuration.

Example 1
The first embodiment relates to processing for converting mask drawing into edge drawing, and will be described in detail with reference to FIGS. 5 and 6.

  FIG. 5 is a flowchart showing details of a processing procedure related to processing for converting from mask drawing to edge drawing.

  First, in step S501, the display list generation unit (210) receives a mask image included in the drawing information as input data.

  In step S502, the display list generation unit (210) determines whether the size of the received mask image is equal to or smaller than a threshold value. The threshold value is a constant that can be set to a different value depending on the configuration of the control device (110) and the performance of the CPU (112).

  If the size of the mask image is equal to or smaller than the threshold value, the process proceeds to S507. For example, as shown in FIG. 4B, even if the mask image is data related to a checkered pattern, since the number of edges included in the mask image is small, it is desirable to convert it into edge data. Accordingly, the process proceeds to step S507, and after changing the mask drawing to edge drawing, an optimum display list is generated for the rendering processing unit (215) to increase the speed.

  On the other hand, if the size of the mask image is equal to or larger than the threshold value, the process proceeds to step S503, and the image cache state is determined. This image cache is a storage device used for temporarily storing the rendering processing result when the rendering processing unit (215) processes and renders the mask image included in the display list.

  In step S504, it is determined whether or not there is a free space in the image cache during rendering. For example, as shown in FIG. 4A, when it is determined that there is no free space in the image cache due to overlapping drawing of mask images, the process proceeds to step S507, and the mask drawing is converted into edge drawing. Thereby, in the rendering processing unit (215), data is stored within the range of the capacity of the image cache, so that the rendering process can be performed at high speed.

  If it is determined in step S504 that the image cache capacity is free at the time of rendering, the process proceeds to step S505, where the mask image is read, and the number of edge data included therein is counted. This edge data is a change between 0 and 1 as shown in the mask image (304), and the number is counted.

  In step S506, it is determined whether the number of edges is equal to or less than a threshold value. In step S506, the data for which the edge density is determined to be greater than or equal to the threshold value is, for example, checkered pattern data as shown in FIG. When this checkerboard pattern data is rendered by edge drawing, the load on the rendering processing unit (215) increases because there are many edges. Therefore, if the number of edges is not less than or equal to the threshold value, the process proceeds to step S508, and the mask image is not converted as it is. On the other hand, if it is determined in step S506 that the number of edges is equal to or less than the threshold value, the number of edges included in the mask image is not large, and thus the process proceeds to step S507 to convert the mask drawing into edge drawing.

  FIG. 6 is a diagram schematically showing processing for converting mask drawing into edge drawing. FIG. 6A shows an example of drawing by mask drawing. Note that the example mask drawing data is such that characters of different colors are drawn for each mask by performing mask drawing four times.

  FIG. 6B is a schematic diagram illustrating a state where there is data cached in excess of the image cache capacity when the rendering processing unit 215 processes the mask images overlapped as illustrated in FIG. It is the figure shown in.

  The rendering processing unit (215) caches images on the same scan line in units of image data in order to execute rendering processing in units of scan lines. Further, in the case of the data in FIG. 6A in which the data of the mask A to the mask D are overlapped and drawn at the same place, the mask image is put into the image cache of the rendering processing unit (215) in the image loading order.

  For example, the cache period of the mask A exists on the image cache while rendering the range of the scan line indicated by the wavy arrow in FIG. 6B, and is erased when the scan line direction advances from the wavy arrow.

  In the case of the example shown in FIG. 6B, when the scan line rendering between the wavy arrows is performed on the mask data shown in FIG. 6A, the image cache overflows. The rendering processing unit (215) has an image cache therein, and speeds up the rendering process by fetching image data to be loaded for scanline rendering into the image cache. However, the number and size of the image cache are limited. If the image cache overflows, it takes time because the image loading process sequentially reads the image data in the RAM (116), not from the cache. Processing is slow.

  For example, in the case of data on the image cache to load one pixel, one clock is required, but when it is on the RAM (116), four clocks are required. Therefore, when the image cache overflows as shown in FIG. 6C, the process of the flowchart shown in FIG. 5 is executed to convert the mask image into edge data. By this conversion, the rendering process can be executed while the mask image is in the image cache, and the mask image can be processed at high speed.

  FIG. 10A is a table showing an example of the effect when the mask data shown in FIG. 6A is processed according to the embodiment of the present invention. The data shown in FIG. 6A, which previously took 11.36 seconds for the rendering processing unit (215), generates an optimal display list obtained by converting mask drawing into edge drawing by the display list generation unit (210). By doing so, it can be shortened to 0.18 seconds.

(Example 2)
A second embodiment of the present invention for converting edge drawing into mask drawing will be described with reference to FIGS.

  FIG. 7 is a flowchart showing details of a processing procedure regarding processing for converting from edge drawing to mask drawing as image drawing.

  First, in step S701, the display list generation unit (210) receives edge data included in drawing information as input data.

  In step S702, it is determined whether the number of overlaps in the edge data is greater than or equal to a threshold value. Here, this threshold is a constant that varies depending on the configuration of the control device (110) and the performance of the CPU (112), and can be arbitrarily set. If the number of overlapping edge data is less than or equal to the threshold value in step S702, the required amount of image cache for rendering does not increase, and the process proceeds to step S708 while maintaining edge drawing.

  On the other hand, if the number of overlaps in the edge data is greater than or equal to the threshold in step S702, the amount of edge cache required for the rendering processing unit (215) may exceed the capacity, and the process advances to step S703. Then, the amount of free cache for edge sort processing is confirmed.

  In step S704, it is determined whether there is a free edge cache. If it is determined in step S704 that the rendering processor (215) executes rendering, the edge cache determines that there is a free space that can be accommodated in the capacity, and the process proceeds to S708, where the edge drawing is not converted.

  On the other hand, if it is determined in step S704 that the required amount of edge cache exceeds the capacity when the rendering processing unit (215) executes rendering, the process proceeds to S705.

  Next, when it is determined in step S705 that there are two or more vacant spaces in the image cache, the process proceeds to step S709 to convert edge drawing into mask drawing. On the other hand, if it is determined in step S705 that there are not two or more vacant spaces in the image cache, the process proceeds to step S706 and the edge data is spooled. In step S707, the display list generation unit (210) communicates with the rendering processing unit (215) to render a plurality of spooled edge drawings. Normally, rendering is started after the display list for one page is completed. On the other hand, in the embodiment of the present invention, since it can be stored in the image cache, in step S710, a plurality of edge drawings are partially rendered in advance. Then, by converting the drawing into one mask image drawing, an optimal display list that is within the capacities of the edge cache and the image cache is generated, and the process ends.

  8 and 9 are diagrams for explaining an example of processing for converting edge drawing into mask drawing.

  FIG. 8A shows an example of an image drawn by edge drawing.

  For the image shown in FIG. 8A, edge drawing may be performed a plurality of times in application processing. For example, as shown in FIG. 8B, there is edge data for performing edge drawing seven times.

  FIG. 8B shows that there is more data to be cached than the capacity of the edge cache in the processing by the rendering processing unit (215). That is, when the rendering processing unit (215) performs rendering processing in units of scan lines and the edge data overlaps, it is necessary to load a plurality of edge data even on the same scan line, and the capacity of the edge cache is reduced. It may exceed.

  Therefore, when the capacity of the edge cache is exceeded, the edge data is converted into mask data as in the embodiment of the present invention. By this conversion, the edge data can be executed while being stored in the capacity of the edge cache, and can be processed at high speed.

  In FIG. 8C, when the processing according to the flowchart shown in FIG. 7 in the second embodiment is executed and it is determined that more data is cached than the capacity of the edge cache, a part of the edge data is used as mask data. Convert and store the mask data in the image cache. Since the glyph cache is enabled and can be processed together in the image cache as one common image, the image cache is used.

  FIG. 9A shows an example where the overlapping edge data is different. Since “A” and “B” are determined to operate inside the edge cache, they can be processed inside the edge cache. Since the edge cache overflows at the time “C”, the edge data is converted into a mask image and processed in the image cache. Furthermore, when “D” and “E” mask images are entered, the image cache overflows. For this reason, the edge drawing of “D” and “E” is partially rendered in advance and combined into one mask image drawing, thereby preventing overflow from the image cache. FIG. 9B shows a case where the number of edge data to be spooled is increased to four. In this way, the process of rendering the drawing in advance and combining it into one mask image drawing is performed after spooling up to the last drawing object, so any data can be prevented from overflowing from the image cache. .

  FIG. 10 (b) is a specific example showing the effect of the present invention targeting FIG. 8 (a). Conventionally, the rendering processing unit (215) takes 52.04 seconds, and the display list generation unit (210) generates an optimal display list obtained by converting edge drawing to mask drawing. By doing so, it can be shortened to 0.22 seconds.

100 Image Processing Device 110 Control Device (Controller Unit)
112 CPU
114 ROM
116 RAM
120 Reader Device 130 Printer Device 150 Operation / Display Unit 160 Image Storage Unit 191 PC

Claims (16)

A drawing means for drawing an image;
Determining means for determining whether or not a predetermined free space is available when the drawing means draws the image in the cache memory used when the drawing means draws the image;
The drawing means includes
The image is drawn by a drawing method determined based on a determination result by the determination unit, and the drawing method determines whether a pixel color in an area corresponding to the image is a designated color or a background color. Image processing characterized by mask drawing for drawing the image by determining each image, or edge drawing for drawing the image by painting the inside of the image with a specified color according to information indicating the image outline apparatus. The determination means includes
Determining whether or not a predetermined space is available when the drawing means draws the image by mask drawing in the cache memory used when the drawing means draws the image by mask drawing; and
The drawing means includes
The image is drawn by mask drawing when the determination unit determines that the space is available, and the image is drawn by edge drawing when the determination unit determines that the space is not available The image processing apparatus according to claim 1 . The determination means includes
Determining at least whether or not a predetermined space is available when the drawing means draws the image by edge drawing in the cache memory used when the drawing means draws the image by edge drawing;
The drawing means includes
The image is drawn by edge drawing when the determination unit determines that the space is available, and the image is drawn by mask drawing when the determination unit determines that the space is not available. The image processing apparatus according to claim 1 . Drawing an image by mask drawing is a region corresponding to the image using a mask image having ON information with the pixel color as the designated color or OFF information with the pixel color as the background color for each pixel. included by determining the per pixel and whether the background color to the specified color the color of the pixel is, in any one of claims 1 to 3, characterized in that by drawing the image on The image processing apparatus described. The drawing means stores the mask image in the cache memory when drawing an image by mask drawing,
The image processing apparatus according to claim 4 , wherein the mask image remains stored in the cache memory while the image is drawn by mask drawing. Drawing an image by edge drawing means that the image is drawn by painting the inside of the outline of the image with a specified color in accordance with information indicating the outline obtained by extracting the outline of the image. The image processing apparatus according to any one of claims 1 to 5 . Display list generation means for generating a display list including information on an image drawing method;
Rendering means for rendering the image indicated by the display list;
With
The image processing apparatus, wherein the display list generation unit generates the display list in which the rendering method is changed according to a cache memory capacity required when the rendering unit renders the image. The drawing method is mask drawing or edge drawing,
Mask drawing is a drawing method for drawing the image by determining for each pixel whether the color of the pixel in the area corresponding to the image is the designated color or the background color,
The image processing apparatus according to claim 7 , wherein the edge drawing is a drawing method for drawing the image by painting the inside of the image outline with a specified color according to information indicating the image outline. The image processing apparatus according to claim 7 , wherein the display list generation unit changes the drawing method according to a size of the image. The image processing apparatus according to claim 7 , wherein the display list generation unit changes the drawing method according to the number of edges of the image. The image processing apparatus according to claim 7 , wherein the rendering unit performs rendering by superimposing the images. The rendering unit stores information necessary for rendering a common image among the images to be superimposed in the cache memory, and is necessary each time the common image is superimposed and rendered. The image processing apparatus according to claim 11 , wherein information is used. Wherein the image is an image processing apparatus according to any one of claims 1 to 12, characterized in that a character. A drawing step for drawing an image;
A determination step of determining whether or not a predetermined free space is created when the image is drawn in the drawing step in a cache memory used when the image is drawn in the drawing step;
The drawing step includes
The image is drawn by a drawing method determined based on a determination result in the determination step, and the drawing method determines whether a pixel color in a region corresponding to the image is a designated color or a background color. Image processing characterized by mask drawing for drawing the image by determining each image, or edge drawing for drawing the image by painting the inside of the image with a specified color according to information indicating the image outline Method. The determination step includes
It is at least determined whether or not a predetermined free space is created when the image is drawn by mask drawing in the drawing step in the cache memory used when the image is drawn by mask drawing in the drawing step. ,
The drawing step includes
When the determination step determines that the space is available, the image is drawn by mask drawing, and when the determination step determines that the space is not available, the image is drawn by edge drawing. The image processing method according to claim 14 . The determination step includes
At least a determination is made as to whether or not a predetermined free space is created when the image is drawn by edge drawing in the drawing step in the cache memory used when the image is drawn by edge drawing in the drawing step. ,
The drawing step includes
The image is drawn by edge drawing when the determination step determines that the space is available, and the image is drawn by mask drawing when the determination step determines that the space is not available The image processing method according to claim 14 .

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