JP3211545B2 - Image processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for processing image information having mixed colors, gradations, images, photographs, characters, and line drawings.

[0002]

2. Description of the Related Art To store a high-quality color image, an enormous capacity represented by the number of pixels × the number of gradation bits × the number of colors is required. For example, it takes about 12 to process one page of a full-color printer A3 size of 400 pixels / inch.
8M bytes of memory are required. For this reason, various compression methods have been proposed for compressing image images. For example, JPEG (Joint Photographic coding Experts Gr
oup) is a typical compression method. On the other hand, when document information mainly composed of character information generated by a computer is output to a printer, a page description language PDL is used.
Is sent to the printer as a file represented by
The information is interpreted by the printer, expanded into image information, and appears as visible information on paper.

Even if the color information is enormous, there is a problem if the compression processing is simply performed. Since information such as images and line drawings are mixed in PDL, simple compression processing causes image quality degradation. Japanese Patent Laid-Open No.
88751 has been proposed. Also, PD sent
Since it is not known in advance what data is included in L and how much, it is necessary to be able to handle all cases, and it is necessary to have several memories individually. Therefore, enormous capacity is required as a result to process PDL data normally.

In the configuration shown in the block diagram of FIG. 3 of Japanese Patent Application Laid-Open No. Hei 4-88851, the image data is developed once and then stored as it is in the resolution memory and the gradation memory. Here, it is assumed that a simple line drawing has a little color, but in some cases, more than twice the memory of one page, such as a sampled image obtained by scanning a halftone dot image with a scanner. Because of the necessity, a processing device having a one-page memory that is not compressed may be less expensive.

[0005]

However, according to the prior art, not only a resolution priority such as a line drawing and a gradation priority such as image data but also a PDL including a color line drawing in which resolution and gradation information are mixed and gradation information are mixed. There was a problem that it could not be processed efficiently. The purpose of the present invention is to
An object of the present invention is to provide an image processing apparatus that efficiently develops various types of image information expressed in DL within a fixed amount of memory and does not show deterioration in image quality.

[0006]

In order to achieve the above object, an image processing apparatus according to the present invention as defined in claim 1 converts contents described in a page description language into a plurality of types of attribute data in page units. Recognizing means for classifying, a plurality of attribute developing means for developing each attribute data classified by the recognizing means for each block composed of a plurality of lines including one, and converting the data developed by the attribute developing means to each attribute data Compression means for compressing each data, a block memory for storing data compressed by the compression means, and compressed data for each attribute included in each line based on the compressed data for each attribute stored in the block memory. Command generating means for sequentially generating a command consisting of information for decompressing the compressed data of the positional relationship and each attribute; And it is configured to include a page memory for storing the command. According to a second aspect of the present invention, in the image processing apparatus of the first aspect, the size of the compressed data of each attribute stored in the block memory is detected, and when the size is equal to or larger than a predetermined size, The configuration is provided with means for changing the compression method of the compression means. According to a third aspect of the present invention, there is provided an image processing apparatus comprising: a page memory for storing compressed data of each attribute in each line, a positional relationship thereof, and a command comprising information for restoring the compressed data of each attribute; Means for sequentially reading the commands stored in the memory; means for restoring compressed data of each attribute of the command read by the reading means based on information for restoring the compressed data; Means for synthesizing the data restored every time based on the information on the positional relationship of the compressed data of each attribute of the command.

[0007]

According to the first aspect of the present invention, data described in PDL is received via a communication medium, and the content described in a page description language is classified into a plurality of types of attribute data in page units by a recognition unit. I do. Each of the classified attribute data is decompressed by the attribute decompression means for each block composed of a plurality of lines including 1, and then compressed for each attribute data by the compression means and stored in the block memory. The command generating means sequentially generates, based on the compressed data of each attribute stored in the block memory, a command comprising compressed data of each attribute included in each line, a positional relationship thereof, and information for restoring the compressed data of each attribute. Generate and store in page memory.
In accordance with the stored command, the compressed data extracted from the page memory is decompressed and subjected to print output processing. According to the second aspect of the present invention, the size of the compressed data of each attribute stored in the block memory is detected,
If the size is equal to or larger than a predetermined size, the compression method of the compression unit is changed, and the compressed data of each attribute is compressed by the optimal method. According to the third aspect of the present invention, the page memory stores the compressed data of each attribute in each line, the positional relationship thereof, and a command consisting of information for restoring the compressed data of each attribute. The compressed data of each attribute of the command read by the reading means are respectively decompressed by the decompression means based on the decompression information, and are synthesized by the synthesizing means based on information on the positional relationship of the compressed data of each attribute of the command. Is done.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the image processing apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 shows a functional configuration of an image processing apparatus according to a first embodiment of the present invention. FIG. 2 shows the memory structure. FIG. 3 shows a hardware configuration of the image processing apparatus.
In FIG. 3, the arithmetic unit 20 interprets PDL information sent from an external device via the data communication unit 2, classifies the data into a plurality of types of attribute data in page units, and develops the data into a plurality of line blocks including 1 I do. As a result of expanding the data into one or more line blocks, it is detected whether the number of data of the shape data, the color data, the image data and the shape / color mixed data exceeds a certain reference value. The data is compressed by the circuit 22 and stored in the disk memory 25. At the same time, a combination command indicating how the attribute data is classified and which compression method has been used for compression processing is stored in the memory 24. When outputting the PDL information, the decompression circuit 24 converts the PDL information read out from the disk memory 25 for each of one or more line blocks into
Based on the combination command, the data is expanded and expanded in the page memory and output to the synthesizing circuit 26. The synthesizing circuit 26 synthesizes the PDL information decompressed for each attribute for each page based on the combination command, and then outputs the PDL information to the recording device via the image output interface 27.

The processing based on the above configuration will be described in more detail. In FIGS. 1 and 3, the P
The DL file 13 is once taken into the disk memory 25 via the data communication unit 2. The identification unit 3 classifies the PDL into four attributes 14 in order from the beginning of the file. FIG.
, Attributes 1 to 4 are shape data, color data, image data, and shape color mixed data.
The specification of PostScript, a typical example of PDL, is Adobe
Post Script Langua published by System Incoporated
ge Reference Manual.

Graphics and fonts can be roughly divided into operators for expressing visible information. There is a color operator that expresses colors in graphics and an image operator that handles sampled image information. These are converted to the coordinate system of the output device. Here, as a pre-process for facilitating printer output, when converted to the coordinate system of the output device, the data is rearranged from the one closer to the origin, that is, the one with the smaller address. Expanding Postscript Operators for Sorted Postscript Operators for Each Attribute
Expand with The work area 15 is adapted to the coordinate system of the image output device connected via the image output interface 27, and in this case, is a memory for eight lines of a device capable of printing A3 short hand. 16 pixels / mm (400D
In PI, there are 38,016 pixels (one line is 4752 pixels).
Pixel). In the coordinates, all the information included from the address 0 to the address 38015 pixels is developed.

Next, compression of the expanded image data will be described. The shape data adopts a binary data compression encoding process for the expanded 8 line information for each line.
Shape data is mainly composed of fine line drawing information, and image noise is easily visible. Therefore, encoding uses a reversible method without information deterioration. For example, a run length compression method is used. The result of the compression process is stored in the block memory 9.

The color data is closely related to the shape data processing, and the change points of the shape data include the change points of the color data. As above, the coordinates are from address 0 to 38015
Expand all the information included up to the pixel. The address information is represented by, for example, a run-length compression method according to the shape data, and the color information is stored in a table in correspondence with the position information. Similarly, for the sampled image information, all the information included in the coordinates from address 0 to address 38015 pixels is processed. An image that has not been compressed is stored for each 8-line image information, and a multi-valued image compression process is performed. Since the sampled image information does not include a high frequency component such as a line drawing, an irreversible compression method having a high compression rate is used. For example, JPEG, which is being standardized, is suitable.

Since the shape and color mixture information does not exist alone as an operator, as a result of expanding the shape and color data for each line, if the color data exceeds a certain number (value), it is determined to be the shape and color mixture information. For example, 500 or more is the shape color mixing information, and for example, a run length compression method and a color table of 1000 or less are adopted. 100
If it exceeds 0, the data amount is compressed once by the error dispersion method from the expanded one line data, and the result is compressed by the run length compression method and stored in the color table. In the case of 2500 or more, the resolution of the expanded one-line data is reduced to half, and the result is subjected to run-length compression processing and stored in a color table.

If further image quality is required, it is determined how many resolutions can be obtained within the range in which the amount of change in the color information is changing. Save the number of iterations in a table. Here, the table is provided in the command memory 8 and the block memory 9 shown in FIG. According to the above-described embodiment, the result of decompression and compression processing into four attributes respectively enters the work area provided in the block memory 9, but the sum of the data amounts falls within a range of a preset value. Find out if there is. To process the optimal compression method for each attribute in the block units, including one line, it is possible to realize a high compression ratio with a small work area. The value is, for example, one tenth of the maximum page memory size of the processing device divided by the number of blocks so that the block memory is sufficiently smaller than the page memory.

Next, the above values will be described in more detail. Note that this corresponds to the processing of steps 7 to 11 in FIG. First, the value is compared with the processing result set in the size control. If the result of the check is larger than the set value, the compression process is performed again in order to obtain a higher compression ratio from an attribute that does not easily affect the image quality due to the characteristics of human eyes. In particular, for sampled image information, resampling processing for thinning out the resolution is effective. If the result still exceeds the set value, the compression of the shape / color mixed data is processed again to obtain a higher compression ratio. If the result of the check is smaller than the set value, as a result, the positional relationship of the data processed for each of the four attributes and information on which compression method was finally selected are combined for each line to generate a command. Then, the data is stored in the block memory and the command memory. The data in the work area is stored in the page memory, and the process proceeds to the next block.

Next, the same processing is repeated at addresses 38016 to 76031, and when the last data processing of the page is completed, the processing shifts to the next page. Page memory 19
Can store 10 processed results. PD received
If the L information exceeds ten sheets, it is output when the processing for up to ten sheets is completed. If the number is less than ten, print processing is performed at the end of the page. When printing, based on the data stored in the page memory, the decompression unit 11 decompresses the image data in real time while referring to the command memory in synchronization with an external image output device. Combine and print out.

For example, a description will be given by taking character data as an example. In FIG. 4, first, a fetched PDL information is interpreted by a recognition unit to determine a character (S1), and the positional relationship of attributes other than the character is determined by a combination command. (S2). The character data is developed line by line by the attribute developing unit 1 (S
3). It is divided into shape and color information (S4). From the compression, run-length compression is selected for position information (S5). From the compression, the color information selects run-length compression and a table method (S
6). The compressed data is stored in the block memory (S7). The amount of data stored in the block memory is compared with a number (value) preset for size control (S
8). As a result, when the accumulated data amount is smaller than the set value, the data is accumulated in the page memory (S1).
0). If it is larger than the set value, another compression method is selected (S11), and the process of step 7 is performed again.

In the present embodiment, the classified attribute data is configured to be compressed in the block memory after being compressed through the decompressing unit. However, as shown in FIG. 5, the attribute data is temporarily stored in the block memory 13 through the decompressing unit. It is also possible to store the data and then perform a compression process. Generally, the processing of the attribute developing unit takes the longest time. In particular, if the compression processing cannot be performed at high speed, it takes more time, so that storing the data in the block memory once is effective in terms of processing speed. Further, in the present embodiment, the description has been made using the disk memory. However, the processing speed can be improved by partially using the IC memory.

In this embodiment, the compression is independent of the compressions a to d for each attribute. However, since the compression method is internal processing of the image processing apparatus, the most suitable compression method for the image can be selected. Therefore,
The compression unit 6 shown in FIG. 6 is provided with a plurality of compression schemes, receives the processing result of the attribute expansion unit, selects the processing result, and processes it. With this configuration, the compression method can be a standardized compression method described in the embodiment and a combination thereof, or a unique method suitable for an image.

According to the present embodiment, the following effects can be expected. That is, (1) For the attribute of the PDL of interest, the attribute is identified in advance for each attribute, processed in block units, optimal compression processing is performed for each attribute, the data amount is checked, and compression is performed again as necessary. Further, it is possible to provide an image output device in which the deterioration of the image quality is not noticeable with a small work memory / page memory. (2) If the work memory is provided on the hard disk and the page memory is minimized, normal printing can be performed with about one fifth of the conventionally required page memory. (3) Print processing can be performed on data described in any PDL. (4) An apparatus capable of continuously printing ten different originals at once can be realized by holding one page memory required conventionally. (5) In this embodiment, the description is made using 400 DPI. However, if the resolution is higher, for example, 600 DPI, the effect is further enhanced.

The present invention includes the following embodiments. (1) The recognition means converts the attribute data into at least shape data,
Provide a function to classify color data, image data and shape color mixed data. (2) The compression means has means for detecting that the result of expansion for each of a plurality of line blocks including 1 has exceeded the number of color data exceeding a certain reference data size. By providing the function of performing the compression process, it is possible to achieve high image quality and reduce the memory. (3) By using lossless compression processing for shape data and color data and irreversible compression processing for image data as compression means, high image quality can be realized with optimal compression. (4) The compression means has a function of performing processing selected from a plurality of different compression methods based on the resolution information in the line direction of the shape color mixed data, so that the compression ratio is high,
High image quality can be realized.

[0022]

As described above, according to the present invention, the PDL
By paying attention to these attributes, the attributes are identified in advance and processed in units of blocks, and optimal compression processing is performed for each of the attributes.

[Brief description of the drawings]

FIG. 1 is a functional block diagram according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a memory structure according to an embodiment of the present invention.

FIG. 3 is a block diagram illustrating a hardware configuration according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a flow of processing of character data as one of attribute data classified into a plurality of types.

FIG. 5 is a functional block diagram of an image processing apparatus configured to temporarily store data decompressed for each attribute according to another embodiment of the present invention in a block memory before compressing the data.

FIG. 6 is a functional block diagram of an image processing apparatus according to another embodiment of the present invention, which is configured to be able to select an optimal compression method according to a data amount.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Host, 2 ... Data communication part, 3 ... Identification part, 4 ... Attribute development part, 5 ... Combination command, 6 ... Compression part, 7 ... Size control part, 8 ... Command memory, 9 ... Block memory,
10 page memory, 11 expansion unit, 12 synthesis unit

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumihiko Shibata 2274 Hongo, Fujigo Rocks, Ebina-city, Kanagawa Prefecture References JP-A-4-88572 (JP, A) JP-A-7-168681 (JP, A) JP-A-7-65177 (JP, A) JP-A-6-125454 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) H04N 1/41-1/419 G06T 9/00 B41J 5/30

Claims (3)

(57) [Claims] 1. A recognizing means for classifying contents described in a page description language into a plurality of types of attribute data on a page-by-page basis, and each attribute data classified by the recognizing means for each block composed of a plurality of lines including 1. A plurality of attribute decompression means for decompressing each of them; a compression means for compressing data decompressed by the attribute decompression means for each attribute data; a block memory for storing data compressed by the compression means; Command generation means for sequentially generating, based on the stored compressed data of each attribute, compressed data of each attribute included in each line, a positional relationship thereof, and a command comprising information for restoring the compressed data of each attribute, An image processing apparatus comprising: a page memory for storing a command generated by the command generation unit. 2. The image processing apparatus according to claim 1, wherein a size of the compressed data of each attribute stored in the block memory is detected, and when the size is equal to or larger than a predetermined size, a compression method of the compression unit is used. An image processing apparatus characterized by comprising means for changing the image processing. 3. A page memory for storing compressed data of each attribute in each line, a positional relationship thereof, and a command comprising information for restoring the compressed data of each attribute, and a command sequentially stored in the page memory. Reading means; means for restoring compressed data of each attribute of the command read by the reading means based on information for restoring the compressed data; and data restored for each attribute by the restoring means. Means for synthesizing based on information on the positional relationship of the compressed data of each attribute of the command.