JP4423812B2 - Drawing processing apparatus and drawing processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drawing processing apparatus and a drawing processing method for use in a so-called image rendering that is mounted on a printer or the like.
[0002]
[Prior art]
In recent years, the performance of personal computers (PCs) has made it possible to easily create color documents, and documents output from printers are also becoming more sophisticated. For this reason, it is necessary to improve the capability of the printer itself in order to cope with the sophistication of documents. On the other hand, the price of printers is strongly demanded due to the lower price of PCs. In other words, printers are required to achieve both high performance and low price.
[0003]
The capability of a printer is generally expressed by processing speed, resolution, and gradation. For example, it is expressed by numbers such as 20 PPM (Page Per Minutes), 1200 DPI (Dot Per Inch), and 8 bits / component. It can be evaluated that the larger these values are, the higher the capability of the printer. On the other hand, although there are a plurality of factors that determine the cost of the printer, a CPU (Central Processing Unit) and a memory that are indispensable for forming an image are classified into those having a relatively high price composition ratio. However, since high performance of the CPU is indispensable for realizing high processing speed, in order to achieve both high performance and low price of the printer, it is necessary to reduce the memory capacity installed. Absent. Furthermore, as the resolution and gradation are improved, the amount of data required for processing increases. Therefore, in order to achieve both high performance and low price, the technical problem of how to form high-quality images (how to perform image rendering) with a limited amount of memory becomes significant. .
[0004]
As a process for solving the technical problem in performing such image rendering, for example, Japanese Patent Application Laid-Open No. 10-116160 proposes a so-called fallback process. That is, in this publication, by performing fallback processing, (1) while ensuring the real-time property when outputting an image, (2) expressing data to be drawn in a limited amount of memory Is possible.
[0005]
Here, this fallback processing will be described in more detail. However, the fallback processing is originally applied for the above two purposes (1) and (2), but here, the description will focus on the case where it is applied for the above purpose (2). To do.
[0006]
FIG. 22 is a flowchart illustrating a procedure of the entire image rendering process when the fallback process is performed. The image rendering process is performed for each page of the output image, for example. In other words, when drawing data to be image-rendered is input (step 601; hereinafter, step is abbreviated as “S”), the drawing data is sequentially converted into an intermediate code (also referred to as a graphics order) in a predetermined format (S602). ). Then, it is checked whether or not a so-called memory overflow occurs in which the data amount of the intermediate code is larger than the memory capacity for storing and storing it (S603). If there is no memory overflow, the intermediate code is stored and stored in the memory as it is. (S604). However, if memory overflow occurs, the fallback process is activated (S605). This series of processing is repeated until one page of the output image is completed (S606).
[0007]
FIG. 23 is a flowchart showing a conventional fallback processing procedure. The conventional fallback process consists of the following five processing steps. That is, when the fallback process is activated, first, if there is a raster-like image portion in the intermediate code to be processed (managed in units of bands), the raster portion is losslessly compressed (reversible). Compression) (S701). If a sufficient memory capacity cannot be secured as a result, the raster portion is lossy compressed (lossy compression) (S702). If sufficient memory capacity cannot be ensured by this (when the intermediate code is larger than the band buffer), the entire band is pre-rendered (S703). If a sufficient memory capacity cannot be secured by this, the entire band is losslessly compressed (S704). If a sufficient memory capacity cannot be secured by this, the entire band is lossy compressed (S705). By going through these five processing steps (S701 to S705) in sequence, it is possible to hold and store an intermediate code corresponding to one page of the output image or its compressed data even with a limited capacity memory. . In addition, since the character / graphic part other than the raster part is kept lossless until the fourth step (S704), it can be expected to generate a high-quality image.
[0008]
When the intermediate code for one page of the output image (including the compressed data if fallback processing is performed) is accumulated by such fallback processing or without depending on the fallback processing, As shown in FIG. 22, a page output process is performed (S607), and the printer engine or the like forms an output image. At this time, if there is any lossy compressed band in the page to be output, the entire page including the band is lossy compressed and output. This is to prevent a defect caused by a change in image quality at the boundary between the lossy compressed band and the lossless compressed band.
[0009]
[Problems to be solved by the invention]
However, the above-described conventional fallback processing is very useful in effectively utilizing a limited amount of memory, but there are problems that can hinder high image quality as described below. As a result, it may be difficult to achieve both high performance and low price in a printer or the like.
[0010]
For example, in the conventional fallback processing, lossless compression is performed in the fourth step (S704) of the five processing steps (S701 to S705), but the intermediate code to be processed is an object related to the image attribute. Even if information (information enabling identification of characters, figures, images, etc.) is included, there is a problem that all the object information disappears at the stage of lossless compression. In general, when performing image output, output processing is often performed according to object information. For example, edges of characters and figures are emphasized, and raster-like image portions express rich gradation. . However, if the object information disappears, such processing cannot be performed, and it is considered difficult to realize a high-quality image.
[0011]
Further, for example, in the conventional fallback processing, if even one lossy band exists in a page, the entire page is lossy compressed. Processing on the entire page is a general problem when processing in band units, and is inevitable in order to maintain consistency on the entire page. However, when lossy compression is applied to the entire page, lossy compression that causes image quality degradation is applied to areas that can be expressed with sufficient image quality and a small amount of data. It becomes a big hindrance in doing.
[0012]
Therefore, the present invention provides a rendering processing apparatus and rendering processing capable of realizing high-quality image output while using a limited amount of memory by enabling fallback processing with higher image quality than before. It aims to provide a method.
[0013]
[Means for Solving the Problems]
The present invention provides an intermediate code generating means for converting drawing data into a first intermediate code of a predetermined format when drawing data for drawing an image is received by a drawing processing device devised to achieve the above object. Using the intermediate code storage means for sequentially holding and storing the first intermediate code converted by the intermediate code generation means, and the first intermediate code stored in the intermediate code storage means, Performing decompression into a second intermediate code in a compressible format, compression means for compressing the second intermediate code in scanline units decompressed by the decompression means, and data compressed by the compression means Decompression processing means for decompressing and returning to the second intermediate code; Compressed data storage means for holding and storing data compressed by the compression means; Memory management means for determining whether or not a memory overflow occurs in which the memory capacity that can be used by the intermediate code storage means is insufficient, and when the memory management means determines that memory overflow occurs, the expansion means Fallback processing means for compressing the second intermediate code expanded by the compression means; The intermediate code storage means and the compressed data storage means together When the first intermediate code or the compressed data corresponding to the predetermined image amount is held and accumulated, the output transfer means performs an output process for the first intermediate code or the compressed data corresponding to the predetermined image amount. If it is not determined by the memory management means that memory overflow occurs, the intermediate code generation means sequentially stores and stores the first intermediate code converted by the intermediate code generation means, and the memory management means causes memory overflow. The fallback processing means, when the fallback processing is performed for the second time or later, the decompression processing means decompresses the post-compression data obtained by the fallback processing already performed, About the decompressed second intermediate code and the first intermediate code that causes the fallback process for the second and subsequent times, When the first intermediate code is overlapped in scan line units by the opening means and expanded into a second intermediate code, the second intermediate code after the expansion is compressed by the compression means. The second intermediate code expanded by using the first intermediate code that causes a new fallback process by the expansion means is compressed by the compression means.
[0014]
The present invention is also a drawing processing method devised to achieve the above object. That is, a drawing processing method used when drawing processing is performed with a memory of a limited capacity. When drawing data for drawing an image is received, the drawing data is converted into a first intermediate code of a predetermined format. Using the intermediate code generation step, the intermediate code accumulation step for sequentially storing and storing the first intermediate code converted in the intermediate code generation step in the memory, and the first intermediate code accumulated in the intermediate code accumulation step A decompression step of superimposing in units of scan lines and expanding into a second intermediate code in a compressible format; and a compression step of compressing the second intermediate code in units of scan lines expanded by the expansion step; A decompression process step of decompressing the data after compression by the compression step and returning it to the second intermediate code; A compressed data storage step for holding and storing data after compression by the compression step; A memory management step for determining whether or not a memory overflow occurs in a state where the capacity of the memory is insufficient; and if the memory management step determines that a memory overflow occurs, the second step expanded by the expansion step A fallback processing step for compressing the intermediate code by the compression step; In the intermediate code accumulation step and the compressed data accumulation step An output transfer step for performing output processing on the first intermediate code or the compressed data corresponding to the predetermined image amount when the first intermediate code or the compressed data corresponding to the predetermined image amount is held and accumulated. If it is not determined that the memory overflow occurs in the memory management step, the first intermediate code converted in the intermediate code generation step is sequentially held and accumulated in the intermediate code accumulation step, and the memory management step causes the memory overflow. If it is determined that, in the fallback processing step, if the fallback processing is the second time or later, the decompressed data obtained by the fallback processing already performed is decompressed by the decompression processing step, Causes the expanded second intermediate code and the second and subsequent fallback processes With respect to one intermediate code, it is overlapped in units of scan lines by the expansion step and expanded to a second intermediate code, the second intermediate code after the expansion is compressed by the compression step, and fallback processing is performed. In the first case, the second intermediate code expanded by using the first intermediate code that causes a new fallback process by the expansion step is compressed by the compression step. .
[0015]
According to the drawing processing apparatus having the above-described configuration and the drawing processing method having the above procedure, when a memory overflow occurs, the memory should be stored and accumulated. Second intermediate code Compression processing is performed. However, even if compression processing is performed, the compressed data is decompressed by performing decompression processing on the compressed data after the compression processing. Second intermediate code You can return to That means The intermediate code is overlaid by the expansion means (decompression step). In the second and subsequent fallback processes, the compressed second intermediate code is expanded, and the expanded data and a new intermediate By superimposing the code and compressing it, a high-quality image output can be obtained while using a limited amount of memory. further, By compression process Second intermediate code Specific information attached to the (for example, object information about image attributes) Second intermediate code Are not converted into data of a completely different format (for example, raster-like bitmap data) by the compression process. Therefore, for example, if memory overflow is not resolved even after compression processing, the compressed data after the compression processing is Second intermediate code It is possible to perform lossy compression with a higher compression rate only on a specific portion (for example, an image portion) of the pre-compression data using the pre-compression data returned to the above.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a drawing processing apparatus and a drawing processing method according to the present invention will be described with reference to the drawings.
[0017]
[Description of schematic configuration of drawing processing apparatus]
First, a schematic configuration of the drawing processing apparatus will be described. FIG. 1 is a block diagram illustrating an example of a schematic configuration of a drawing processing apparatus according to the present invention, and FIG. 2 is a schematic diagram illustrating a configuration example of a system in which the drawing processing apparatus is used.
[0018]
The drawing processing apparatus described in the present embodiment is used in a system in which a client 1 and a printer 2 are connected to each other via a network line 3 as shown in FIG. Here, the drawing processing apparatus may be installed in the client 1, installed in the printer 2, or distributed in the client 1 and the printer 2. For example, as shown in FIG. 2B, when the print server 4 is provided on the network line 3, each device 1, including the print server 4 is installed in the print server 4. 2 may be distributed and mounted.
[0019]
When the drawing processing apparatus used in such a system receives drawing data created by application software (for example, document creation software) installed in the client 1, for example, image rendering processing is performed based on the drawing data. Are output and the printer engine of the printer 2 outputs the image. The general procedure for performing this image rendering process is the same as the conventional one (see FIG. 22), and therefore detailed description thereof is omitted here.
[0020]
In order to perform such an image rendering process and a process associated therewith, the drawing processing apparatus is configured as shown in FIG. 1, for example. That is, the drawing processing apparatus includes an intermediate code generation unit 11, an intermediate code storage unit 12, a memory management unit 13, a fallback processing unit 14, an intermediate code expansion unit 15, a compression processing unit 16, and an expansion processing unit. 17, a compressed data storage unit 18, and an output transfer unit 19.
[0021]
Upon receiving drawing data for drawing an image, the intermediate code generation unit 11 converts the drawing data into an intermediate code having a predetermined format as will be described later. That is, the intermediate code generation unit 11 performs the process of S602 in FIG.
[0022]
The intermediate code storage unit 12 sequentially stores and stores the intermediate codes converted by the intermediate code generation unit 11. That is, the intermediate code storage unit 12 performs the process of S604 in FIG.
[0023]
The memory management unit 13 determines whether or not a memory overflow occurs in which the memory capacity that can be used by the intermediate code storage unit 12 is insufficient. That is, the memory management unit 13 performs the process of S603 in FIG.
[0024]
When the memory management unit 13 determines that the memory overflow occurs, the fallback processing unit 14 operates the compression processing unit 16, operates the expansion processing unit 17 as necessary, and then restarts the compression processing unit 16. It is what makes it work. That is, the fallback processing unit 14 performs the processing of S605 in FIG. However, in the drawing processing apparatus described in the present embodiment, the fallback processing unit 14 is significantly different from the conventional one.
[0025]
The intermediate code expansion unit 15 expands the intermediate code converted by the intermediate code generation unit 11 into a compressible format as described later.
[0026]
The compression processing unit 16 performs a compression process on the expansion result by the intermediate code expansion unit 15 to reduce the data amount.
[0027]
If necessary, the decompression processing unit 17 performs decompression processing on data after the compression processing unit 16 performs compression processing (hereinafter referred to as “compressed data”), and returns the compressed data to the format before compression. Is.
[0028]
The compressed data storage unit 18 holds and stores the post-compression data compressed by the compression processing unit 16 according to an instruction from the fallback processing unit 14.
[0029]
When the intermediate code accumulating unit 12 and the compressed data accumulating unit 18 hold and accumulate the intermediate code or the compressed data for an amount corresponding to a predetermined image amount, for example, one page of the output image, the output transfer unit 19 An output process is performed on the intermediate code or the compressed data. That is, the output transfer unit 19 performs the process of S607 in FIG.
[0030]
In the output processing by the output transfer unit 19, the intermediate code decompressing unit 15 and the compression processing unit 16 are operated independently from the compression processing by the instruction from the fallback processing unit 14, and the intermediate code can be compressed. It is assumed that the process of decompressing and compressing is included. This is because even if the intermediate code is directly output to the printer engine or the like, it is difficult to drive the printer engine or the like synchronously. That is, the complexity of the intermediate code (particularly the degree of overlap and the drawing area) is not uniform, and it is difficult to predict the time required for the development process of the intermediate code. Since it is not known where to develop), it is considered effective to compress the intermediate code in order to guarantee the real-time performance of the printer engine, etc. (decompression time is generally easy to guarantee real-time performance) Because. However, if real-time performance can be guaranteed, the intermediate code may be edited and converted into another intermediate code format, or may be output after raster development with a page memory.
[0031]
[Explanation of intermediate code]
Next, the intermediate code format converted by the intermediate code generation unit 11 and the intermediate code expansion method by the intermediate code expansion unit 15 in the drawing processing apparatus configured as described above will be described.
[0032]
The drawing data received by the intermediate code generation unit 11 usually includes object information (information that makes it possible to identify characters, graphics, images, etc.) relating to image attributes specified by the drawing data. Also, a wide variety of expansion methods are known for expanding the intermediate code into a compressible format. However, for example, if raster development of the intermediate code is performed, compression is possible, but the amount of data increases, and the object information disappears at that point, which is not desirable.
[0033]
Therefore, the drawing processing apparatus according to the present embodiment employs a form in which the intermediate code expansion result is output as the second intermediate code, the intermediate code generation unit 11 converts the drawing data into the intermediate code, and further expands the intermediate code. Even if the unit 15 expands the intermediate code into a compressible format, the object information is not lost while being maintained. That is, in the drawing processing apparatus of the present embodiment, the intermediate code generation unit 11 converts the drawing data into the first intermediate code, and the intermediate code expansion unit 15 further compresses the first intermediate code in the second format. Is expanded to the intermediate code.
[0034]
The format of the first intermediate code at this time may be any format such as a vector format, a trapezoid format, or a run length format as long as it can be acquired in units of scan lines. The reason that the format needs to be acquired in units of scan lines is that the intermediate code expansion unit 15 performs expansion processing in the following procedure. FIG. 3 is a flowchart illustrating an example of an intermediate code expansion processing procedure.
[0035]
That is, the intermediate code development unit 15 first acquires all data on the uppermost (or even the lowermost) scan line (S101). Then, the leftmost drawing point (in the case of drawing from left to right or the rightmost drawing in the case of drawing from right to left) is acquired (S102), and is the drawing point the drawing start point? It is determined whether or not (S103).
[0036]
In the case of the drawing start point, the intermediate code development unit 15 registers that the drawing data has started drawing (S104). Then, it is determined whether it is the uppermost data (drawn later in the drawing order) in the drawing data that has started drawing (S105). If it is the uppermost data, it is further below this drawing data (drawing order). (S106), if there is, the left side of the point of interest (coordinate point of the drawing data that started drawing) from the paint start point with the color of the lower drawing data. (S107), and the coating start point is changed to the point of interest (S108). However, when the drawing start data is not the uppermost side or when there is no drawing data that has started drawing on the lower side, the processing up to the change of the paint start point is skipped.
[0037]
On the other hand, if it is not the drawing start point (drawing end point), the intermediate code development unit 15 determines whether it is the uppermost drawing data that has started drawing (S109). Color is applied from the paint start point to the point to the left of the target point (S110), and the paint start point is changed to the target point (S108). However, if it is not the uppermost drawing data in the drawing start, the processing up to the change of the paint start point is skipped.
[0038]
Thereafter, the intermediate code development unit 15 determines whether or not all the data on the scan line has been processed (S111), and if it still remains, returns to the acquisition of the leftmost drawing point and performs the above-described processing (S102). To S110). If all of the data have been processed, it is determined whether there is an unprocessed scan line in the band that is a predetermined processing unit (S112). If there is still a scan line, the process returns to data acquisition on the scan line. The above-described processing (S101 to S111) is repeated. When all the processes are performed, the process in one band is ended.
[0039]
Here, the format of the first intermediate code handled in the expansion process of the procedure as described above will be described. Here, a vector format is taken as an example as the first intermediate code.
[0040]
FIG. 4 is an explanatory diagram showing an example of a data representation format using vectors. In the figure, “order” is a drawing order of drawing commands. “X” indicates the value of the X intercept of the vector across the current scan line. “X displacement” indicates the amount of change in the X intercept when the process moves to the next scan line. “Y displacement” indicates the number of remaining scan lines affected by the vector. “Direction” indicates the direction of the vector.
[0041]
The vector having such a configuration will be described in more detail. FIG. 5 is an explanatory diagram showing a specific example of data represented by vectors. In the figure, the coordinate system has an origin at the upper left, and therefore, the X coordinate value increases in the horizontal right direction in the figure, and the Y coordinate value increases in the vertical downward direction in the drawing. In the illustrated example, a triangle represented by three points P1 (0, 300), P2 (600, 0), and P3 (300, 600) is shown. From these three points, three vectors P1P2, P2P3, and P3P1 are generated in consideration of the direction of the vector. In P1P2, “X” is 600, “X displacement” is −2, “Y displacement” is 300, and “direction” is −1. The other vectors are similarly shown in the figure.
[0042]
By the way, in the case of the vector format, it is necessary to determine whether the figure is internal or external. FIG. 6 is an explanatory diagram showing a specific example of rules used for internal / external determination of a figure. There are two types of determination rules: a non-zero winding rule shown in FIG. 6A and an odd / even rule shown in FIG. These are all rules used when determining the inside of one figure formed by a plurality of external shapes (paths).
[0043]
The non-zero winding rule shown in FIG. 6A considers the direction when the outer shape constituting the figure intersects the scan line. That is, the case where the outer shape crosses the scan line upward is positive, and the case where the outer shape crosses downward is negative. If the crossing is positive in the scanning direction, 1 is added, and if it is a negative crossing, 1 is subtracted, and it is determined that the point from the point where the total value is no longer 0 to the point where it returns to 0 is inside. To do. On the other hand, the odd / even rule shown in FIG. 7B counts the number of paths crossing the scan line, and determines from odd points to even points as internal.
[0044]
The internal determination process based on such a determination rule is used for determining the drawing start point and the drawing end point in the expansion process described with reference to FIG. Here, the internal determination process will be described in more detail. FIG. 7 is a flowchart illustrating an example of the procedure of the internal determination process. Note that there is a separate attribute area (internal determination rule and internal determination value) corresponding to the drawing figure, which can be obtained from a value indicating the drawing order.
[0045]
When the internal determination process is performed, first, an internal determination rule for a graphic composed of the vectors is acquired from the vector order (S201). If the type of the internal determination rule is a non-zero winding rule (S202), an internal determination value is subsequently acquired (S203), and it is checked whether or not the value is “0” (S204). When the value is “0”, the direction of the vector is added (S205), and it is determined that it is “start of region” (S206). On the other hand, if the value is not “0”, the direction of the vector is added (S207), and it is checked again whether the value is “0” (S208). If the value is “0”, it is determined that “the end of the region” is set (S209), and if the value is other than “0”, it is determined that the region is continued (S210).
[0046]
If the type of the internal determination rule is an odd / even rule (S202), the internal determination value is subsequently acquired, the value is increased by "1", and a remainder of 2 is obtained (S211). If the value of the remainder of 2 is “1”, the determination result is an odd number (S212), and since the figure is inside, it is determined that “region start” (S213). On the other hand, if the remainder of 2 is “0”, the determination result is an even number and is outside the figure, so it is determined as “end of region” (S214).
[0047]
In the internal determination process of such a procedure, “region start” corresponds to the drawing start point, and “region end” corresponds to the drawing end point. Therefore, if the internal determination process described above is applied to each acquired vector, the drawing start point and the drawing end point can be determined.
[0048]
Here, the first intermediate code has been described by taking a vector format as an example. However, as the first intermediate code, other formats (such as run-length format) may be mixed. Not too long.
[0049]
Next, the format of the second intermediate code, which is the result of performing the expansion process described with reference to FIG. 3 on the first intermediate code described above, will be described. Here, a run length format is taken as an example of the second intermediate code.
[0050]
FIG. 8 is an explanatory diagram showing an example of a data representation format by run length. In the example of the figure, two types of run length formats are shown, but as a common structure, a field (type) that represents the type and data format of the object, and a field (start point) that represents the start coordinate value on the scan line, And a field (end point) representing the end coordinates on the scan line. However, in one “type 1”, the color value is embedded in the run length, while in the other “type 2”, the color value is a pointer and a pixel row is stored in another area. Normally, the “type 1” format is used to represent characters and graphics, and the “type 2” format is used to represent rasters.
[0051]
As described above, the intermediate code expansion unit 15 expands the first intermediate code converted by the intermediate code generation unit 11 into a second intermediate code in a compressible format. As part of this, it also has a function of performing data overlay processing described below.
[0052]
FIG. 9 is a flowchart illustrating an example of a procedure of data superimposition processing performed as part of the intermediate code expansion processing. Here, as shown in the upper part of the figure, three drawing data that overlap each other on a certain scan line are input, and the drawing order is data that is drawn first on the lower side and data that is drawn later on the upper side. As an example, the content of each drawing data is “blue” graphic data at the bottom, raster data “green” at the center, and character data “red” at the top.
[0053]
In this case, first, in the first step (S301), the drawing start point is acquired, but since no drawing data has been started before that, the coordinate value of the drawing start point is temporarily used as the paint start point. Fasten to hold on. Thereafter, in the next step (S302), the drawing start point of “green” is acquired, but nothing is done because “red” drawn after green has already started drawing. In the next step (S303), the drawing end point of “red” is acquired, and since it is the top in the drawing data that has started drawing, “red” from the paint starting point “0” to its coordinate value “5” is obtained. ”Is output, run-length data such as“ type 1, red, 0, 5 ”is output, and the paint start point is updated to“ 6 ”.
[0054]
In the next step (S304), the drawing start point of “blue” is acquired, but nothing is done because “green” drawn after “blue” has already started drawing. In the next step (S305), the drawing end point of “green” is acquired, and since it is the top of the drawing data that has been drawn, from the paint starting point “6” to the coordinate value “9”. It decides to paint “green”, outputs run-length data such as “type 2, green pixel row, 6, 9”, and updates the paint start point to “10”. In the next step (S 306), the drawing end point of “blue” is acquired, and since it is the top of the drawing data that has been drawn, from the painting start point “10” to its coordinate value “13”, “ It decides to paint with “blue”, outputs run-length data such as “type 1, blue, 10, 13”, and updates the paint start point to “14”.
[0055]
As described above, the intermediate code expansion unit 15 is one of the formats that can be compressed while performing data overlay processing on the first intermediate code converted by the intermediate code generation unit 11 as necessary. It is designed to expand to a second intermediate code in run length format.
[0056]
[Description of compression processing]
Next, the compression process performed by the compression processing unit 16 will be described. A wide variety of compression methods for intermediate codes developed into a compressible format are known. Here, a case where a color image encoding method described below is applied is taken as an example.
[0057]
FIG. 10 is a block diagram illustrating an example of a functional configuration in the compression processing unit. As shown in the figure, the compression processing unit 16 in the present embodiment includes a reference area generation unit 16a, an identical pixel value distribution generation unit 16b, a prediction information encoding unit 16c, an error calculation encoding unit 16d, and a code synthesis. And means 16e.
[0058]
The reference area generation unit 16a extracts pixel data to be encoded and a plurality of pixel data in the peripheral area from data input pixel by pixel in the raster scan order, and extracts these as target pixel data and reference area, respectively. Data.
[0059]
Based on the target pixel data and reference region data specified by the reference region generation unit 16a, the same pixel value distribution generation unit 16b distributes the pixels having the same pixel value as the target pixel around the target pixel. And the result is output as the same pixel value distribution.
[0060]
The prediction information encoding unit 16c encodes the target pixel value based on the same pixel value distribution detected by the same pixel value distribution generation unit 16b if the target pixel data can be encoded only by the same pixel value distribution. On the other hand, if the encoding is impossible, a code indicating that the encoding is impossible is generated, and these are selectively output as the prediction information code data.
[0061]
The error calculation encoding means 16d calculates a predicted pixel value from the pixel value data, calculates and encodes an error between the predicted pixel value and the pixel value data, and outputs it as predicted error code data.
[0062]
The code synthesizing unit 16e synthesizes the prediction information code data from the prediction information encoding unit 16c and the prediction error code data from the error calculation encoding unit 16d, and outputs it as a single code stream.
[0063]
When the compression processing unit 16 having such a configuration receives data to be subjected to compression processing, the reference area generation unit 16a and the surrounding pixel (the pixel value of the pixel (target pixel) to be encoded in the received data) For example, pixel values of peripheral four pixels) are extracted, and these are specified as target pixel data and reference area data, respectively. As an arrangement of the pixel of interest and its peripheral pixels, for example, a specific example shown in FIG. 11 can be considered. It is assumed that the position of the pixel of interest is scanned in order for one page as in the pixel scanning order.
[0064]
When the pixel-of-interest data and the reference region data are specified, subsequently, in the compression processing unit 16, the same pixel value distribution generation unit 16b determines whether the reference region data has the same pixel value as the pixel-of-interest data. Are compared, and the results are collectively output as the same pixel value distribution. For example, the same pixel value distribution generation unit 16b replaces peripheral pixels having the same pixel value as the pixel value of the target pixel with “1”, other peripheral pixels with “0”, and collects the replaced peripheral four pixels. Are output as the same pixel value distribution. Therefore, for example, in the case of the specific example shown in FIG. 12, the same pixel distribution is generated in which “1” is directly above and to the left of the target pixel, and “0” is the others.
[0065]
Thereafter, in the compression processing unit 16, the prediction information encoding unit 16c encodes the same pixel distribution generated by the same pixel value distribution generation unit 16b, and outputs the result as prediction information code data. At this time, the prediction information encoding unit 16c performs encoding for the same pixel distribution according to the preset reference pixel label and code generation table. Examples of the reference pixel label and the code generation table include the specific example shown in FIG.
[0066]
At the same time, in the compression processing unit 16, the error calculation encoding unit 16d encodes the same pixel distribution generated by the same pixel value distribution generation unit 16b, and the result is predicted error code data. Output as. At this time, the error calculation encoding unit 16d performs encoding on the same pixel distribution by an arithmetic encoding method using a preset arithmetic expression. An example of the arithmetic expression is a specific example shown in FIG.
[0067]
When the prediction information code data and the prediction error code data are output from the prediction information encoding unit 16c and the error calculation encoding unit 16d, respectively, in the compression processing unit 16, the code synthesizing unit 16e combines these to generate a single unit. Is output as a code stream. However, at this time, for example, in the code synthesizing unit 16e, when the same information is continuously output as the prediction information code data output by the prediction information encoding unit 16c, the number of consecutive times is counted. After the codes are not the same, output together with the count result. Therefore, for example, if the prediction information code data and the prediction error code data as in the specific example shown in FIG. 15A are output, the code synthesizing unit 16e combines them as shown in FIG. 15B. Data will be output.
[0068]
[Explanation of decompression process]
Next, the decompression process performed by the decompression processing unit 17 will be described. The decompression processing by the decompression processing unit 17 is performed on the data after compression by the compression processing unit 16. Therefore, here, a case where a color image decoding method described below is applied as an expansion method is taken as an example in response to the description of the compression processing described above.
[0069]
FIG. 16 is a block diagram illustrating an example of a functional configuration in the decompression processing unit. As shown in the figure, the decompression processing unit 17 in this embodiment includes a code determination unit 17a, a prediction information decoding unit 17b, an error decoding addition unit 17c, and an intermediate code generation unit 17d. Yes.
[0070]
The code discriminating unit 17a reads data after compression by the compression processing unit 16 and discriminates whether each code constituting the data after compression is prediction information code data or prediction error code data. is there.
[0071]
When the code constituting the compressed data is the prediction information code data, the prediction information decoding unit 17b decodes the prediction information code data and associates it with the encoding, for example, the reference pixel shown in FIG. Return to information about the label. Furthermore, information (count result) indicating how many times the same prediction information code data continues is also decoded.
[0072]
The error decoding addition means 17c calculates the value of the target pixel based on the error value of the prediction error code data when the code constituting the compressed data is prediction error code data. As a calculation method, it is conceivable to derive an arithmetic expression for calculating a target pixel value from an arithmetic expression used at the time of encoding, and use the arithmetic expression. For example, when encoding is performed using the arithmetic expression shown in FIG. 14, an arithmetic expression such as pixel of interest = (A + B) / 2 + error may be used.
[0073]
The intermediate code generation means 17d uses the prediction information decoded by the prediction information decoding means 17b and the error information decoded by the error decoding addition means 17c to generate data in a format before compression, for example, an intermediate code in run length format. Is to be generated.
[0074]
Here, the intermediate code generation processing by the intermediate code generation means 17d will be described in more detail. FIG. 17 is a flowchart illustrating an example of an intermediate code generation procedure.
[0075]
As shown in the figure, the intermediate code generation means 17d first acquires the decoded data (S401), and whether or not the pixel value of the data is equal to the pixel on the left (or the pixel value of the current run length). Is checked (S402). As a result, if they are equal, the length of the acquired data (the number of consecutive identical pixel values in the case of prediction information, “1” in the case of error information) is added to the length of the current run length ( S403). If they are not equal, the current run length is output and a new run length is started (S404). At this time, the new run length has the pixel value and length of the acquired data as initial values. The intermediate code generation unit 17d returns the compressed data to the same state as the second intermediate data in the run-length format by repeatedly performing the above processing until there is no decoded data (S405).
[0076]
[Explanation of fallback processing]
Next, a fallback process by the fallback processing unit 14 that is the most characteristic process in the drawing processing apparatus according to the present embodiment will be described. The fallback process is a process performed when memory overflow occurs, as is apparent from the flowchart of FIG. 22 described above. Therefore, in the fallback process, it is necessary to reduce the amount of data to be stored and accumulated in the memory.
[0077]
There are various methods for reducing the amount of data. In the drawing processing apparatus of the present embodiment, a high compression rate is obtained for character graphics and CG (Computer Graphics) images by the encoding method by the compression processing unit 16 described above. Can guarantee. Therefore, the fallback processing unit 14 can reduce the data amount by operating the compression processing unit 16 in the case of a character graphic and a CG image. On the other hand, natural images (images) expressed by bitmap raster data are difficult to compress at a high compression rate while maintaining high image quality, as is generally said. However, on the other hand, the image is not noticeable to human eyes even if the image quality is degraded. Therefore, in the present embodiment, when compressing an image, a case where a high compression rate is ensured by performing a process for reducing the resolution will be described as an example. However, this is for simplifying the explanation, and there is no problem even if another method is used to ensure a high compression rate. Another method includes, for example, a combination of other encoding methods such as JPEG (Joint Photographic Experts Group).
[0078]
In this manner, applying different encoding methods for each image object such as a character graphic and an image can be realized based on the object information. For this reason, in the rendering processing apparatus of this embodiment, object information is handled in the same way as pixel values, and the object information is restored even after undergoing compression processing and decompression processing. Specifically, as shown in FIG. 18, object information and pixel information are handled in a lump and used to determine prediction information at the time of encoding / decoding. That is, even if the pixel value is the same, if the object information is different, it is handled as different data.
[0079]
Here, the fallback processing by the fallback processing unit 14 will be described in detail with a specific example. FIG. 19 is an explanatory diagram showing a specific example of the configuration of the object of the page to be processed. In FIG. 19A, the hatched (hatched) portion is a portion where characters are written, and the filled (black) portion is an image portion, and the image occupies the upper right quarter of the page. In addition, as the drawing order, after drawing the character area, the image area is drawn. Furthermore, it is assumed that the page is divided into four bands and processed as shown in FIG.
[0080]
FIG. 20 is an explanatory diagram showing in more detail the object configuration shown in FIG. 19, particularly the object configuration in the uppermost band. As shown in the figure, this band is mainly composed of the page margin (background), characters, background, image, and background. In more detail, although the character portion and the background portion are mixed in the character portion, it is simply treated as a character here, and the description is simplified.
[0081]
When drawing data for drawing a page having such an object configuration is received, in the drawing processing apparatus of this embodiment, first, the intermediate code generation unit 11 converts drawing data related to characters into a first intermediate code. The intermediate code storage unit 12 holds and stores this. After that, the intermediate code generation unit 11 converts the drawing data relating to the image into the first intermediate code, and the intermediate code storage unit 12 holds and stores this, but at this time (in the intermediate encoding stage of the image) An example will be described in which the memory management unit 13 determines that memory overflow occurs and the fallback processing unit 14 performs the fallback processing.
[0082]
FIG. 21 is a flowchart illustrating an example of a fallback process procedure according to the present embodiment. When the memory overflow occurs and the fallback processing needs to be performed, the fallback processing unit 14 determines whether or not the fallback processing has already been performed on the same page to be processed, that is, newly It is determined whether or not the fallback process to be performed is a second or later process (hereinafter referred to as “multiple fallback process”) (S501). This determination may be made based on the presence / absence of post-compression data, processing history, and the like.
[0083]
If the result of this determination is multiple fallback processing, since there is compressed data for the same page, the fallback processing unit 14 operates the decompression processing unit 17 to perform decompression processing on the compressed data. The compressed data is returned to the same state as the second intermediate data in the run length format (S502). The decompression processing by the decompression processing unit 17 at this time is performed according to the procedure already described (see FIGS. 16 and 17).
[0084]
Then, the fallback processing unit 14 treats the intermediate data after the decompression process as run-length data for the background pattern, and performs a data overlay process for synthesizing the run-length data with an intermediate code that causes a new fallback process. Then, the intermediate code expansion unit 15 is caused to perform (S503). The data superimposing process at this time is performed according to the procedure already described (see FIG. 9). However, the drawing data has a vertical relationship as described above, and the generation of the intermediate code is performed in the drawing order. Therefore, in the data overlay process, the fallback processing unit 14 gives an instruction to put the run-length data after the decompression process below the intermediate code that causes a new fallback process. As a result, the intermediate code expansion unit 15 arranges the decompression result of the fallback processing up to the previous time on the lowest side of the data format having the vertical relationship.
[0085]
On the other hand, if it is determined that it is not a multiple fallback process, the decompression process (S502) and the data overlay process (S503) are skipped.
[0086]
Thereafter, the intermediate code expansion unit 15 performs expansion processing on the intermediate code after the data superimposition processing or the intermediate code that causes the new fallback processing, and creates a second intermediate code in the run length format ( S504). The expansion process at this time is performed according to the procedure already described (see FIGS. 3 to 9). Then, the fallback processing unit 14 operates the compression processing unit 16 to perform compression processing on the intermediate code generated by the intermediate code expansion unit 15 (S505). The compression process at this time is also performed in the procedure already described, as in the decompression process (see FIGS. 10 to 15).
[0087]
Here, the fallback processing unit 14 inquires of the memory management unit 13 whether or not the memory capacity is sufficient by the above-described series of processing (S501 to S505) (S506). As a result, if there is sufficient free space, the fallback processing unit 14 checks whether or not it is the end of the page (S507), and repeats a series of processing (S501 to S507) if it is not yet over. Then, the memory capacity for one page of the output image is secured, and the intermediate code storage unit 12 or the compressed data storage unit 18 holds and stores the intermediate code or the compressed data.
[0088]
However, when the compression processing unit 16 performs the compression process and the memory capacity is not sufficient, the fallback processing unit 14 operates the decompression processing unit 17 to obtain the post-compression data obtained by the compression process. A decompression process is performed on (S508). The decompression process at this time is also performed according to the procedure already described (see FIGS. 16 and 17). Therefore, the compressed data returns to the same state as the second intermediate code in the run length format. In addition, at this time, since the object information and the pixel value are handled in the same manner, the object information for the intermediate code is restored in the same manner as the compressed data returns to the intermediate code.
[0089]
Therefore, the fallback processing unit 14 extracts only the image part based on the object information, and performs the data amount reduction process only on the part having the attribute of the image (S509). As the data amount reduction processing at this time, as described above, resolution conversion processing may be mentioned, but an encoding method such as JPEG may be used. After the data of the image portion is reduced, the compression processing unit 16 is operated again, the above-described series of processing (S505 to S509) is repeated, the memory capacity for one page of the output image is secured, and the fallback processing is finished. To do.
[0090]
As described above, according to the drawing processing apparatus and the drawing processing method executed by the drawing processing apparatus according to the present embodiment, compression processing or decompression processing is performed as necessary during the fallback processing. Can be restored to its original format. That is, unlike the conventional case, specific information (for example, object information related to image attributes) attached to the intermediate data is lost by the compression process, or all of the intermediate data is completely different in the format (for example, the object information about the attribute of the image) In other words, it is not converted into raster bitmap data).
[0091]
Therefore, according to the drawing processing apparatus and the drawing processing method of the present embodiment, even when the fallback process is performed, the fallback process and the subsequent process can be performed according to the object information. In the back process, it is possible to perform a compression process with a high compression rate (for example, lossy compression) only on the image portion. Also, since different compression processing can be performed depending on the object, even if there is even one lossy compressed portion in the page, lossy compression of the entire page is not required. Furthermore, even after the fallback processing, for example, the edge portions of characters and figures can be emphasized, and the raster-like image portion can express the gradation richly.
[0092]
In particular, in the drawing processing apparatus and the drawing processing method of this embodiment, lossless compression with a high compression rate is performed only on the image portion when memory overflow is not eliminated only by lossless compression. Therefore, lossy compression is applied only to image parts that are attribute parts where image quality degradation is not noticeable even when lossy compression is applied, and lossless compression is applied to other parts (characters, graphics, etc.). become.
[0093]
For these reasons, according to the drawing processing apparatus and the drawing processing method of the present embodiment, high-quality image output is realized by minimizing the deterioration of the image quality of the output image while effectively utilizing the limited memory capacity. As a result, it is possible to contribute to both high performance and low price in a printer or the like.
[0094]
This is realized by decompressing the compressed data so that it can be returned to the format before compression. In other words, since the compressed data can be returned to the format before compression, if the object information and the pixel information are handled together, the object information is not lost after the decompression process, and the fallback process as described above can be performed. It becomes feasible.
[0095]
In the present embodiment, the case where the compressed data is returned to the second intermediate code in the run-length format by the decompression process has been described as an example, but the present invention is not limited to this. In other words, intermediate codes can be mixed in various formats such as vector format, trapezoid format, run length format, raster format, etc. If the compressed data can be returned to the format before compression, that format Is not limited to a specific one. However, in the compression processing performed as part of the fallback processing, lossy compression and lossless compression are selectively performed according to the object, so if considering the recompression processing performed after the decompression processing, the decompression processing In this case, it is preferable that the compressed data to which lossy compression is applied is decoded by raster expression, and the other compressed data to which lossless compression is applied is decoded by run length expression.
[0096]
【The invention's effect】
As described above, according to the drawing processing apparatus and the drawing processing method of the present invention, it is possible to perform a fallback process with higher image quality than before, thereby enabling high quality while using a limited amount of memory. Image output can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of a schematic configuration of a drawing processing apparatus according to the present invention.
FIGS. 2A and 2B are schematic diagrams illustrating a configuration example of a system in which a drawing processing apparatus according to the present invention is used, in which FIG. 2A is a diagram illustrating an example thereof, and FIG. 2B is a diagram illustrating another example;
FIG. 3 is a flowchart illustrating an example of an intermediate code expansion processing procedure;
FIG. 4 is an explanatory diagram showing an example of a data representation format using vectors.
FIG. 5 is an explanatory diagram showing a specific example of data represented by vectors.
6A and 6B are explanatory diagrams showing a specific example of a rule used for internal / external determination of a figure. FIG. 6A is a diagram showing a non-zero winding rule, and FIG. 6B is a diagram showing an odd / even rule.
FIG. 7 is a flowchart illustrating an example of a procedure of an internal determination process.
FIG. 8 is an explanatory diagram showing an example of a data expression format by run length.
FIG. 9 is a flowchart illustrating an example of a procedure of data superimposition processing performed as part of intermediate code expansion processing.
FIG. 10 is a block diagram illustrating an example of a functional configuration in a compression processing unit of the drawing processing apparatus according to the present invention.
FIG. 11 is an explanatory diagram showing a specific example of reference area data used in compression processing.
FIG. 12 is an explanatory diagram showing a specific example of the same pixel value distribution used in the compression process.
FIG. 13 is an explanatory diagram showing a specific example of a reference pixel label and a code generation table used in compression processing.
FIG. 14 is an explanatory diagram showing a specific example of an arithmetic expression for error calculation encoding used in the compression process.
15A and 15B are explanatory diagrams showing a specific example of an encoding format, in which FIG. 15A is a diagram showing prediction information code data and prediction error code data, and FIG. 15B is a diagram showing their combined data.
FIG. 16 is a block diagram illustrating an example of a functional configuration in an expansion processing unit of the drawing processing apparatus according to the present invention.
FIG. 17 is a flowchart illustrating an example of an intermediate code generation procedure.
FIG. 18 is an explanatory diagram showing an outline of handling object information and pixel information.
FIGS. 19A and 19B are explanatory diagrams illustrating a specific example of the configuration of an object of a page to be processed, where FIG. 19A is a diagram illustrating a state of the entire page, and FIG. 19B is a diagram illustrating a band division state;
20 is an explanatory diagram showing in more detail the object configuration shown in FIG. 19, particularly the object configuration in the uppermost band. FIG.
FIG. 21 is a flowchart showing an example of a fallback processing procedure according to the present invention.
FIG. 22 is a flowchart showing a procedure of the entire image rendering process when a fallback process is performed.
FIG. 23 is a flowchart showing an example of a conventional fallback processing procedure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Intermediate code production | generation part, 12 ... Intermediate code storage part, 13 ... Memory management part, 14 ... Fallback process part, 15 ... Intermediate code expansion | deployment part, 16 ... Compression process part, 17 ... Decompression process part, 18 ... Compressed data Accumulation unit, 19 ... output transfer unit

Claims (6)

Intermediate code generating means for receiving drawing data for drawing an image and converting the drawing data into a first intermediate code of a predetermined format;
Intermediate code storage means for sequentially holding and storing the first intermediate code converted by the intermediate code generation means;
Using the first intermediate code stored in the intermediate code storage means, performing the superimposition in units of scan lines, and developing the second intermediate code in a compressible format;
Compression means for compressing the second intermediate code in scanline units developed by the expansion means;
Decompression processing means for decompressing the data compressed by the compression means and returning it to the second intermediate code;
Compressed data storage means for holding and storing data compressed by the compression means;
Memory management means for determining whether or not a memory overflow occurs in which the memory capacity that can be used by the intermediate code storage means is insufficient;
A fallback processing unit for compressing the second intermediate code expanded by the expansion unit by the compression unit when it is determined that the memory overflow occurs by the memory management unit;
When the intermediate code accumulating unit and the compressed data accumulating unit hold and accumulate the first intermediate code corresponding to the predetermined image amount or the compressed data, the first intermediate code corresponding to the predetermined image amount or the post-compression Output transfer means for performing output processing on data,
If it is not determined by the memory management means that memory overflow will occur, the intermediate code storage means sequentially stores and stores the first intermediate code converted by the intermediate code generation means,
When the memory management means determines that memory overflow occurs, the fallback processing means
When the fallback processing is performed for the second time or later, the decompressed data obtained by the fallback processing already performed is decompressed by the decompression processing means, and the decompressed second intermediate code and the second or later The first intermediate code that causes the fallback processing of the image is overlapped in units of scan lines by the expansion means and expanded into a second intermediate code, and the second intermediate code after the expansion is compressed. Compressed by means,
When the fallback process is performed for the first time, the compression unit compresses the second intermediate code expanded using the first intermediate code that causes a new fallback process by the expansion unit. A drawing processing apparatus characterized by the above. The second intermediate code expanded by the expansion means includes object information related to the attribute of the image represented by the second intermediate code,
The decompression processing means restores the object information when decompressing the compressed data and returning it to the second intermediate code,
The fallback processing means includes
When the fallback processing is performed for the second time or later, the decompressed data obtained by the fallback processing already performed is decompressed by the decompression processing means, and the decompressed second intermediate code and the second or later For the first intermediate code that causes the fallback processing of the image, the object information is used to superimpose the data in units of scan lines by the expansion means, and the second intermediate code is expanded. The drawing processing apparatus according to claim 1, wherein a second intermediate code is compressed by the compression unit. The fallback processing means includes
If the fallback process is the second or later,
The expansion means arranges the second intermediate code expanded by the expansion processing means on the lower side, and superimposes the first intermediate code that causes the second and subsequent fallback processes in units of scan lines. The drawing processing apparatus according to claim 1, wherein the drawing processing device is expanded into a second intermediate code, and the compressed second intermediate code is compressed by the compression unit. The fallback processing means applies the lossy compression processing by the compression means only to an attribute part in which image quality deterioration is not noticeable even when lossy compression is performed based on the object information. The drawing processing apparatus according to claim 2. The decompression processing means decodes the compressed data to which the lossy compression processing by the compression means is applied by raster representation, and the compressed data to which other lossless compression processing is applied by the run length representation. The drawing processing apparatus according to claim 4, wherein: A drawing processing method used when drawing processing is performed with a limited amount of memory,
An intermediate code generating step of receiving drawing data for drawing an image and converting the drawing data into a first intermediate code of a predetermined format;
An intermediate code storage step of sequentially storing and storing the first intermediate code converted in the intermediate code generation step in the memory;
Using the first intermediate code stored in the intermediate code storage step, performing the superimposition in units of scan lines, and expanding the second intermediate code in a compressible format,
A compression step of compressing the second intermediate code of the scan line unit expanded by the expansion step;
A decompression process step of decompressing the data after compression by the compression step and returning it to the second intermediate code;
A compressed data storage step for holding and storing data after compression by the compression step;
A memory management step for determining whether or not a memory overflow that results in a shortage of memory capacity occurs;
A fallback processing step of compressing the second intermediate code expanded by the expansion step by the compression step when it is determined that the memory overflow occurs by the memory management step;
When the first intermediate code or the compressed data corresponding to the predetermined image amount is held and accumulated in the intermediate code storage step and the compressed data storage step, the first intermediate code or the amount corresponding to the predetermined image amount is stored. An output transfer step for performing output processing on the data,
If it is not determined that memory overflow occurs in the memory management step, the first intermediate code converted in the intermediate code generation step is sequentially held and accumulated in the intermediate code accumulation step,
When it is determined that memory overflow occurs in the memory management step, the fallback processing step includes:
When the fallback process is performed for the second time or later, the decompressed data obtained by the fallback process already performed is decompressed by the decompression process step, and the decompressed second intermediate code and the second or later process are performed. The first intermediate code that causes the fallback processing of the image is overlapped in units of scan lines by the expansion step and expanded to a second intermediate code, and the second intermediate code after the expansion is compressed to the second intermediate code Compressed by steps,
When the fallback process is performed for the first time, the second intermediate code developed using the first intermediate code that causes a new fallback process by the decompression step is compressed by the compression step. A drawing processing method characterized by the above.

Images