JP2002198823A - Device and method for processing information - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the processing time at the time of decoding and transferring compressed information. SOLUTION: An information processor is provided with a compander 210' which decodes compressed image data composed of a plurality of lines, a line information storage device 501 which accumulates the relevance between a plurality of decoded lines, and a storage device 203' which stores at least one of the relevant lines when the plurality of decoded lines have prescribed relevance. The processor is also provided with a DMAC 209' which reads out the line stored in the storage device 203' of the decoded image data from the device 203' and the data about the other lines not stored in the device 203' based on the relevance accumulated in the storage device 501 and delivers and receives the image data readout to a printer engine I/F.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing apparatus for decoding compressed information, and more particularly to a technique for reducing the processing time when decoding and outputting the information to an external device.

[0002]

2. Description of the Related Art In recent years, a document is input to a computer or the like,
It is common to create electronic data with the help of these and print it on paper with a printer. In FIG.
FIG. 1 shows a configuration serving as a basis of the present invention, and is an example of a document processing / creation system. A sentence is input from the terminal device indicated by 101 in FIG.
Document components such as graphics are input, and a set of electronically expressed document data 104 is created by document processing software 103 incorporated in the document 101. The document data 104 is further stored in the document processing software 10.
3 is converted into a data format that can be interpreted by the printer 110 by the printer driver included in the printer 110 and sent to the printer 110. As such a data format, for example, there is a format called PDL (Page Description Language). Printer 110
The printer controller 111 in the inside interprets the transmitted data by a data analysis device built in the 111,
The data is finally developed into a dot pattern that becomes print data.
Then, the developed dot pattern data is sequentially sent to the printer engine 112, and the printer engine 112 fixes and prints the dot pattern data on a medium such as paper with toner.

FIG. 2 is a diagram for explaining the configuration of the printer 110 in more detail. Reference numeral 201 denotes a host I / F that communicates output document data, control signals, and the like with a host such as a computer. Reference numeral 203 denotes a buffer for storing communication data and a storage device for storing dot pattern data after data development. In this example, a DRAM is used. Note that the storage device 203 is also used as a work memory when developing dot pattern data. A memory controller 204 controls read / write of the DRAM. Reference numeral 205 denotes a rasterizer for developing output document data into dot pattern data. Reference numeral 202 denotes a control device that controls the host I / F 201, the memory controller 204, and the rasterizer 205. 2
Reference numeral 08 denotes an engine I which is connected to the printer engine 220 and transmits dot pattern data to the print engine 220.
/ F denotes a DMA 209 for transferring dot pattern data developed from the storage device 203 via the memory controller 204 to the engine I / F 208 by DMA.
It is a controller.

In order to reduce the capacity of the storage device 203, the dot pattern data of the band that has been expanded is once compressed by the compression / decompression device 210,
3, the band is expanded at the timing of printing the band, and then transmitted to the printer engine 220.

Here, various methods can be applied as compression / expansion means in the compression / expansion device 210. If the printer engine 220 prints a monochrome image and handles binary dot pattern data, a means capable of compressing / expanding binary data can be applied as the compression / expansion means.

Among such binary data compression / decompression means, JBIG (Joint) is one of the standardized methods.
Bi-level Image Expert Group). This JB
The IG method employs arithmetic coding and has higher coding efficiency than the MMR method, and it is known that the tendency is particularly remarkable in computer-generated image data.

As described above, the theory of JBIG is well established and standardized. However, when a decoder and a decompressor are actually commercialized, a variety of hardware configurations can be considered. Various studies have been made on what kind of configuration is suitable.

[0008]

In the above-described configuration based on the present invention, when JBIG decoding is performed to transfer image information to a printer or the like, all image data is output to a storage device. Will be.

Generally, in an encoder / decoder using the JBIG system, arithmetic encoding / decoding must be performed for each pixel. However, this arithmetic encoding / decoding processing algorithm, as shown in FIGS.
Since it is very complicated and must perform sequential processing on a pixel-by-pixel basis, much processing time is required for compression / decompression processing.

[0010] However, if the line to be processed completely matches the immediately preceding line, it is only necessary to perform the decoding process for one pixel at the time of decoding. Therefore, it is not necessary to decode the remaining image data of the line, but in the above configuration, it is necessary to repeatedly output the same data as the data of the previous line as the data of the current processing line, during which the decoder There is a problem that it is necessary to wait until the data output ends while the operation is stopped.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has been made in view of the above circumstances. An image decoding means for expanding compressed binary image data, a storage means for storing expanded image data, and the storage means And a direct memory access controller for reading out image data from the printer engine I / F and transferring the image data to the printer engine I / F, wherein the image decoding means decodes the compressed data and determines that the current line completely matches the previous line. Only the information is output to the storage means, and if they do not match, all the image data of the current line are output, and the storage means stores information for distinguishing all output lines of the decoded image data. The direct memory access controller has the information stored in the storage unit based on the information for distinguishing the line. Characterized by sequentially accessing the issue image data.

According to the present invention, when decoding a compressed binary image, image data output from the decoder can be limited to data on a line different from the immediately preceding line. The required processing time can be greatly reduced.

In order to solve the above problems, the present invention provides:
A first storage unit for storing second information generated by compressing the first information, and a plurality of information elements constituting the second information are sequentially read from the first storage unit; Decoding means for decoding and outputting only information elements satisfying a predetermined condition among the outputted information elements; second storage means for storing the information elements output from the decoding means; Reading means for reading the information element stored in the storage means, and for information elements not output to the second storage means, reading a predetermined information element stored in the second storage means; An output device for outputting a series of information elements read by the reading means.

In order to solve the above problems, the present invention provides
The decoding unit includes a determination unit that determines whether a plurality of information elements included in the second information read from the first storage unit are common or similar to each other, When the determining means determines that the plurality of information elements are common or similar, at least one of the plurality of information elements is decoded and output.

Further, in order to solve the above problems, the present invention provides:
The decoding unit outputs information indicating that the output of the information element has been omitted for the information element that has not been decoded, and the reading unit outputs the information based on the information indicating that the output has been omitted. For information elements whose output is omitted,
An information element common or similar to the information element is read from the second storage means.

Further, in order to solve the above problems, the present invention provides:
The decoding means further comprises a creation means for creating management information as to whether or not each of the information elements has been output from the decoding means, wherein the reading means has a function of reading the information element to be processed. And determining whether the information element to be processed needs to be read out by referring to the management information created by the creating means.

Further, in order to solve the above problems, the present invention provides:
The information elements stored in the first storage means include main information and sub-information, and the main information includes information obtained by compressing main components of the first information. The sub-information includes information indicating a relationship between adjacent information elements, and the decoding unit, when decoding the information element, transmits the sub-information before decoding the main information. Decrypting, and the determining means, based on the decrypted sub-information,
It is characterized in that it is determined whether or not a plurality of information elements are common or similar to each other. Further, in order to solve the above-mentioned problem, the present invention provides a third method for storing the management information.
The determination means reads the management information from the third storage means and makes the determination.

Further, in order to solve the above problems, the present invention provides:
It is characterized in that the third storage means can perform reading at a higher speed than the second storage means.

Further, in order to solve the above problems, the present invention provides:
The first information is a binary image.

Further, in order to solve the above problems, the present invention provides:
The first information is a sound, an image, a moving image, a text, or a data file.

Further, in order to solve the above problems, the present invention provides:
The compression method used for information compression of the first information is J
It is characterized by the BIG system.

Further, in order to solve the above problems, the present invention provides:
The output means is an output interface to a printer, facsimile, display device, or personal computer.

In order to solve the above problems, the present invention provides:
The output means is another information processing apparatus itself such as a printer, a facsimile, a display device, or a personal computer.

Further, in order to solve the above problems, the present invention provides:
Decoding means for decoding compressed image data composed of a plurality of lines, storage means for accumulating a mutual relationship between the plurality of decoded lines, and a case where the plurality of decoded lines have a predetermined relationship Is a storage unit for storing at least one of the lines having relevance, a line stored in the storage unit of the decoded image data is read out from the storage unit, and a line not stored is stored in the storage unit. A transfer unit that reads data of another line based on the stored relevance and transfers the read image data to the outside.

Further, in order to solve the above problems, the present invention provides:
A first storage unit for storing second information generated by compressing the first information, and a plurality of information elements constituting the second information are sequentially read from the first storage unit; Decoding means for decoding and outputting only information elements satisfying a predetermined condition among the outputted information elements; second storage means for storing the information elements output from the decoding means; Holding means for temporarily holding the information element read from the storage means; and for the information element stored in the second storage means, reading the information element from the second storage means and holding the information element. Means for temporarily holding the information element, reading the information element from the holding means, and for information elements not stored in the second storage means, reading means for reading the information element currently held in the holding means. , Read out Characterized in that it comprises an output device and for outputting a set of information elements read by stage.

In order to solve the above problems, the present invention provides
It is characterized in that the holding means can perform reading at a higher speed than the second storage means.

In order to solve the above problems, the present invention provides
The capacity of the holding means is equal to or larger than a capacity corresponding to a processing unit in the reading means.

In order to solve the above problems, the present invention provides
Management information creating means for creating management information for managing which information element has been output to the second storage means; and reading means based on the management information created by the management information section. The information processing apparatus further includes a prefetch control unit that causes the holding unit to prefetch an information element to be read.

Further, in order to solve the above problems, the present invention provides:
Storing the second information generated by compressing the first information, sequentially reading a plurality of information elements constituting the second information, and determining a predetermined condition among the read information elements; Decoding only the information elements that satisfy;
Storing the decrypted information element, and reading out the information element stored after decryption,
For the information element that has not been stored, the method includes a step of reading the stored predetermined information element and a step of outputting the read series of information elements.

In order to solve the above problems, the present invention provides:
The decoding step includes determining whether or not a plurality of information elements constituting the second information are mutually common or similar, and determining that the plurality of information elements are common or similar. And decoding and outputting at least one information element of the plurality of information elements.

Further, in order to solve the above problems, the present invention provides:
The decoding step includes a step of outputting information indicating that the output of the information element has been omitted for the information element that has not been decoded, and the reading step includes:
Based on the information indicating that the output has been omitted, the information element of which output is omitted is a step of reading an information element common or similar to the information element.

Further, in order to solve the above problems, the present invention provides:
The decoding step further includes a step of creating management information as to whether or not the information element has been decrypted, and the reading step includes the step of creating the information element prior to reading the information element to be processed. A step of determining whether or not it is necessary to read out the information element to be processed with reference to the management information created in the step (1).

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be disclosed below. This embodiment is provided for the purpose of allowing a person skilled in the art to easily implement the present invention.
Therefore, it is not intended to limit the scope of the claims intentionally. Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 2 shows the basic structure of the present embodiment. FIG. 3 shows a more detailed embodiment of the present invention. For the sake of comparison with FIG. 2, similar or common components are denoted by reference numerals in FIG. A line information storage unit 401 for newly storing line information in this embodiment is added to the storage unit 203 'in FIG. The compression / decompression device 210 ', after setting appropriate parameters by the control unit 202', starts the decoding process and sequentially reads the JBIG-compressed binary image data from the storage means 203 'to perform decoding. . At this time, prior to the decoding process of the code data of each line, a flag indicating that the current processing line is the same as the pre-processing line, that is, the aforementioned LNTP is decoded. If this flag indicates a mismatch between the current processing line and the pre-processing line, a mark indicating that the current line has been output is added to the area corresponding to the current line in the line information, and the subsequent current line Are sequentially decoded.
If this flag indicates that the current processing line matches the pre-processing line, a mark indicating that the output of the current line has been omitted is added to the area corresponding to the current line in the line information, and the next line is immediately displayed. Move on to the decryption process.

This will be described below with specific numerical values. FIG. 4 shows the alphabet character string "AB" on one page.
C to XYZ "is an example of a typical document in which one horizontal line is printed. This page is configured by a bitmap consisting of 6000 pixels × 8000 lines.
An arbitrary pixel position on this page can be represented by a two-dimensional coordinate value (x, y). Here, x represents a pixel position in the horizontal direction, and takes a value from 0 to 5999. Further, y represents a pixel position in the vertical direction, and 0 to 79
Values up to 99 are assumed.

FIG. 4 shows the result of expanding the upper left character "A" into a bit map, which is drawn in an area of 72 pixels wide by 96 pixels long and has coordinates (200, 30) in the page.
0)-(271, 395) are arranged in a rectangular area having a diagonal line.

The other characters "B", "C" to "X", "Y", and "Z" are arranged in the same manner. The columns “ABC to XYZ” are all arranged in a rectangle whose vertical coordinate values take values from 300 to 395. At the point of time when all the character strings of one line have been expanded, the compression / expansion device 210 'as the information of lines 300 to 395 of the line information held by the line information storage unit 501 as shown in FIG. Mark that output has been made.

On the other hand, all lines except the first line in the following lines of the document coincide with the previous line. In this example, since the line spacing is 96 lines, the compression / expansion device 210 'stores data "0" indicating that output has been omitted for the lines 397 to 491 as line information in the line information storage means 501. . The line information is shown in FIG.
As shown in FIG. 7, the data becomes a list in which the line numbers are associated with the marks (flags).

Thus, the compression / decompression device 21
The decoded image data output from 0 ′ is limited, and as a result of decoding a one-page office document, the line information held by the line information storage unit 501 has a mark indicating that the output has been performed. The portion where the line is continuous and the portion where the line without the mark is continuous appear alternately. In the above-mentioned example, 96 continuous lines with the mark indicating that the output has been made and 96 continuous lines without the mark are repeated.

When the decoding process is completed, the expanded image data for one page stored in the storage device 203 'is then transferred to the direct memory controller 20.
9 'read out by the printer engine I / F 20
Passed to 8 '.

FIG. 7 shows a direct memory controller 2
09 'and the outline of the storage device 203' are shown. FIG. 8 shows an outline of the processing. Description of other components is omitted for simplicity. The storage device 203 'stores the decoded image information 700 and the line information 701 corresponding to the image information 700. Direct memory controller (hereinafter sometimes simply referred to as DMAC) 20
9 'reads line information 701 first before reading the contents of each line constituting the image information (8)
01). This processing is performed by the line information reading unit 702. Subsequently, in the line information determination unit 703, the read unit 7
With reference to the line information read out in step S02, it is determined whether or not the line information is a line to which data has been output (802). If the result of the determination is that of the output line, the pixel data read control unit 704 switches the read destination to the address corresponding to the current line (80).
3) Read the pixel data from the storage device (804).
Conversely, if the output is omitted for a line, this means that the data of the last line where the reading process was actually performed and the data of the current line are common or similar. Therefore, the pixel data read control unit 704 replaces the image data of the current line with the data of the last line by reading out the image data of the last output line again from the previous line (805). For example, when the line information of the line 397 is read, it is known that this line is a non-output line. Therefore, the data of the line 396 which is the immediately preceding output line is read again. Note that the last output line can also be specified by referring to the line information. Even if the line information is not directly referred to, the address at the last access to the storage device is held, and if the value is not changed until the next output line comes, the readout can be easily realized again. Hereinafter, the data of the line 396 is repeatedly read out until the line 492 from the line 398 onward. The data read in this way is transferred to the printer via the printer IF. The above operation is repeated until the end of the image information (806).

FIG. 9 shows an example of the configuration of a direct memory controller for performing such a memory access. 301
Is a control unit. 306 is a bus interface for interfacing with the memory controller, and 307 is a buffer for buffering the data width and speed when transferring data to the engine I / F. The image data is stored in the storage device 20
3 'is stored at a continuous address for each line. The line address counter 302 holds the offset to the address of the head data of each line. The pixel address counter gives the relative position of each pixel data with respect to the head data. In this embodiment, for the sake of simplicity, the image data is addressed in units of 8 bits and stored in the storage device 20.
3 ′, the line address counter 302
Is composed of 13 bits, and the pixel address register 304 is composed of 10 bits. It is assumed that a 23-bit address obtained by concatenating these is the address stored in each pixel.

When the control unit 301 starts the DMA transfer, the MUX 308 is switched to the line information address, and the line information of the line 0 is read from the storage unit 203 '. If this indicates an output line, then the MUX 308 is switched to the opposite side. Next, image data is read from an address formed by a combination of a line address and a pixel address, and stored in the buffer 307. The data stored in the buffer 307 is transmitted to the engine I / F 20 at appropriate timing.
Passed to 8 '. Next, the image data of the line is sequentially read out while incrementing the pixel address register 304. When one line of data is read, the line information address register 305 is incremented,
The pixel address counter 304 is reset, and the process proceeds to the next line. If the line information of the next line also indicates that the line is an output line, the line address register 302 is incremented and the read processing of the line data is continued. If the next line is a non-output line, instead of incrementing the line address register 302, the skip counter (initial value 1) is incremented and line data reading is continued similarly. The data read at this time is the immediately preceding output line. Then, at the time when the non-output line changes to the output line, the contents of the skip counter 303 are added to the line address register 302 so that the contents of the line address register 302 indicate the current output line, and at the same time, the skip counter 303 is returned to the initial value.
Continue reading the line data.

By repeating such a procedure for all lines, the decoded binary image data is transmitted to the printer engine 22 via the printer engine I / F 208 '.
Can be passed to 0 '.

As described above, according to the present invention, JB
When the image data output from the compression / decompression device 210 'during IG decoding can be limited, the JBIG compression / decompression device 210' performs JBIG decoding at a rate of one pixel per clock and matches the previous line. If the image is output at the same speed, the time required for JBIG decoding in the above-described example can be reduced to half.

In this embodiment, one page of data is decoded in the storage device 203 '. However, it is needless to say that a configuration in which one page of data is partially decoded, May be decoded at once.

In this embodiment, JBIG is used as the compression / expansion method of the binary image data. However, comparison with the previous line is performed, and if they match, only the information is encoded and the remaining image of the line is encoded. It goes without saying that any compression / decompression method using an algorithm that does not encode data can be similarly applied.

Further, in the present embodiment, the case of a binary image has been described. However, even in the case of a color image, if compression / expansion is performed for each color component in the same manner as the binary image, It goes without saying that the same can be applied.

The same processing as described above may be performed not only when data is common between the preceding and succeeding lines but also when the data is similar. In this case, the original image data may not be accurately reproduced. However, if the application does not care much about the accuracy, such processing may be performed. Although the accuracy is reduced, on the other hand, a shorter processing time can be expected. This is because the degree of similarity is greater than the degree of commonness, and as a result, data output can be omitted for a considerable number of lines. A threshold may be used to determine similarity. The threshold may be determined based on the required restoration accuracy.

Next, the details of the encoding process will be described. FIG. 10 is a flowchart illustrating a process of performing single layer coding of image data using the JBIG method. Procedure INI
When the TENC is activated (900), if the activation is performed after the first stripe or forced reset, the contents of the probability estimation table are cleared and the internal registers are initialized. The probability estimation table contains a one-bit dominant probability symbol MP for each possible value of the context CX.
S (CX) and a 7-bit probability estimation state ST (CX) are stored.

Since there are 10 reference pixels around the pixel to be coded, 210 = 1024 patterns can be taken. The context CX is a value indicating which of the 1024 patterns is present. And is dictated by the template. The template can be selected from two types, a two-line template shown in FIG. 11 and a three-line template shown in FIG. In the figure, the position indicated by the symbol “?” Indicates the current position of the encoding target pixel.

In the next step, the current pixel value P to be encoded
IX, the context corresponding to the pixel to be encoded, and TPVALUE are read (301). Here is TPVA
LUE is an amount determined for each line, and when performing typical prediction, a value indicating whether the line including the pixel to be encoded matches the immediately preceding line, that is, whether the value of one pixel is different from that of the previous line, Take. When the typical prediction is not performed, a value indicating that the line including the encoding target pixel does not match the immediately preceding line is always taken.

When the typical prediction is used, the information is encoded using a special context at the pseudo pixel position shown in FIG. 13 before starting processing of one line. Actually, SLNTP is encoded instead of TPVALUE. Here, SLNTP is obtained by the following equation.

SLNTPy =! (LNTPy XOR L
NTPy-1) Here, LNTPy takes 1 when the y-th line is different from the y-1-th line even by one pixel (the line y is called "typical" at this time), and 0 otherwise. .
Thus, SLNTP is 0 at the change point of LNTP, LNTP
If the value of P does not change continuously, it becomes 1 during that time.

In order to detect the coincidence between the line including the current pixel to be encoded and the immediately preceding line as described above, FIG.
As shown in (1), a line memory for one line is provided in the encoder / decoder, input data is sequentially compared with data of the immediately preceding line, and after one line of data has been input, all pixels match. Or not.

In the next step, the value of TPVALUE is checked (302). If the value of TPVALUE indicates that the line including the pixel to be encoded matches the immediately preceding line, the next step is omitted. TPV
Since the value of “ALUE” is determined for each line, in this case, the encoding process for all the pixels in the processing line is omitted.

Otherwise, the next step ENCODE
In step 303, the encoding target pixel is arithmetically encoded using the context CX corresponding to the pixel value PIX (303).

FIG. 15 shows a flowchart of the ENCODE processing. First, the current encoding target pixel value PIX is compared with the dominant symbol MPS predicted from the context CX (900), and if they match, the A register holding the agent corresponds to the current state ST of the context CX. Gives the probability estimate LSZ (90
1). Next, the value of the A register is compared with 0x8000 (9
02) If the value of the A register is larger, the process proceeds to the next pixel. If the value of the A register is smaller, the value of the A register is compared with the value of the LSZ (903). Based on the result, the value of the A register is added to the value of the code register C, and the value of the LSZ is loaded into the A register (904). ). Next, the state ST in the context CX is updated to NMPS. Next, a so-called normalization process of shifting the A register and the C register to the left is performed until the value of the A register exceeds 0x8000 (905). At this time, a bit string output from the left end of the C register becomes output code data.

The pixel value PIX to be encoded and the dominant symbol M
If the PSs do not match, the probability estimation value LSZ corresponding to the current state ST of the context CX is subtracted from the A register holding the agent (906). Next, the value of the A register is compared with the value of the LSZ (907), and based on the result, the value of the A register is added to the value of the code register C.
The register is loaded with the value of LSZ (908). Next, when the state ST is a predetermined state (909), the value of the dominant symbol in the context CX is exchanged (91).
0). Next, the state ST in the context CX is changed to NLP.
Update to S. Next, a so-called normalization process of shifting the A register and the C register to the left is performed until the value of the A register exceeds 0x8000 (911). Also in this case, the bit string output from the left end of the C register becomes output code data.

FIG. 16 is a flowchart showing a process for decoding single-layer image data using the JBIG method. When the procedure INITDEC is started (40
0), after the first stripe or forced reset, clear the contents of the probability estimation table and initialize the internal registers.

Next, the context corresponding to the pixel to be decoded and TPVALUE are read (402). Here, TPVALUE is an amount determined for each line as in the case of encoding. When performing typical prediction, the line including the pixel to be decoded matches the immediately preceding line, that is, the value of one pixel differs. Takes a value indicating whether or not it should be. When the typical prediction is used, the information is encoded using a special context at the pseudo pixel position shown in FIG. 12, so that this value needs to be decoded in advance before performing the decoding processing of one line. There is. Actually, as described above, TPV
SLNTP is coded instead of ALUE.

In the next step, the value of TPVALUE is checked (403). If the value of TPVALUE indicates that the line including the encoding target pixel matches the immediately preceding line, the value of the pixel decoded at the same pixel position on the immediately preceding line is output. Since TPVALUE is determined for each line, in this case, decoding processing for all pixels in the processing line is omitted.

Otherwise, the next step DECODE
The arithmetic decoding is performed on the pixel value PIX to be decoded by the context CX (404). Thereafter, the procedure DECODE is activated (405), and a DECODE (decoding) process is performed.

FIG. 17 shows a flowchart of the DECODE process. First, the probability estimation value LSZ corresponding to the current state ST of the context CX is subtracted from the A register holding the agent (1000). Next, the contents of the code register C and the contents of the A register are compared (1001). If the value of the A register is larger, the value of the A register is compared with 0x8000 (1002). If the value of the A register is larger, the dominant symbol MPS is output as the value PIX of the pixel to be decoded (1006). To the processing of the pixel. If the value of the A register is smaller, the value of the A register is compared with the LSZ (1004). If the value of the A register is larger, the dominant symbol MPS is output as the value PIX of the pixel to be decoded, and the state in the context CX ST is updated to NMPS, and the process proceeds to the next pixel (1005).

If the A register is smaller than LSZ,
The value obtained by inverting the MPS is output as the value of PIX (100
6), the state ST in the context CX is updated to NLPS (1009), and if necessary (1007), the value MPS of the dominant symbol in the context CX is inverted, and the process proceeds to the next pixel (1008). Next, a normalization process of shifting the A register and the C register to the left is performed until the value of the A register exceeds 0x8000 (1020).

When the A register is smaller than the C register, the value of the A register is compared with LSZ (101).
0), if the value of the A register is larger, the value of the A register is subtracted from the value of the C register, and the value of the LSZ is loaded into the A register (1011). The value PIX of the pixel to be decoded
And outputs the inversion of the dominant symbol MPS (101
2) If necessary (1013), invert the value MPS of the dominant symbol in the context CX (1014),
The state ST in the context CX is updated to NLPS (1015), and the process proceeds to the next pixel. Next, a normalization process of shifting the A register and the C register to the left is performed until the value of the A register exceeds 0x8000 (1016).

If the A register is smaller than LSZ,
The value of the A register is subtracted from the value of the C register, and the value of the LSZ is loaded into the A register (1017). The dominant symbol MPS is output as the value of PIX, the state ST in the context CX is updated to NMPS, and the process proceeds to the next pixel (1018). Next, the value of the A register is 0x800
Normalization processing is performed to shift the A register and the C register to the left until the value exceeds 0 (1019).

The above operation is performed until the stripe is completed (406).

[0069]

[Other Embodiments] Another Embodiment 1 FIG. 18 shows another configuration example of the DMAC 209 ′. The feature of this embodiment is that the read control unit 704 and the storage device 20
3 ′ is provided with a cache memory 705. This cache memory temporarily stores information read from the storage device 203 ′, and preferably has a higher read / write speed than the storage device 203 ′. In general, a high-speed memory is expensive, so that the cache memory only needs to have a capacity that can hold one line of data. Of course, a larger capacity may be used.
The cache memory 705 holds the last line data actually read from the storage device 203 ′.

The operation will be described. First, when the line information determination unit 703 determines that the current line to be processed has been output to the storage device 203 ',
The pixel data read control unit 704 reads data corresponding to the current line from the storage device 203 ′ into the cache 705. Subsequently, the pixel data read control unit 704 reads the data held in the cache, and outputs the read data to the printer as data of the current line. On the other hand, when the line information determination unit 703 determines that the current line to be processed has not been output to the storage device 203 ′, the pixel data read control unit 702 stores the current line in the cache memory 705. Read the data that is stored. In this way, the data read from the cache is supplied to the printer as the data of the line where the output from the decompression unit is omitted. An advantage of this configuration is that since data to be output to the printer is always held in a high-speed memory, an improvement in processing speed can be expected as compared to accessing a low-speed memory every time. 2. Another Embodiment 2 FIG. 19 shows still another configuration example of the DMAC 209 ′. This configuration is characterized by a memory 7 for storing line information.
06 is different from the memory that holds the pixel data. In particular, since line information is frequently accessed on a line-by-line basis, an attempt is made to reduce the access time to the memory by holding the line information in the DMAC. Therefore, the line information holding memory 70
6 is desirably a high-speed reading. Since the line information is very small compared to the pixel data, it is considered that even if the line information holding memory 706 is a high-speed memory, the cost of the entire apparatus is not significantly affected. The capacity of the line information holding memory 706 may be at least a capacity that can store the line information.

Although not shown, the cache memory 705 and the line information holding memory 706 may be used at the same time. 3. Other Embodiment 3 In the embodiment of FIG. 18, a storage device 203 ′ is further provided.
May be pre-read in the memory 705 in advance. That is, the lines from which data is actually read from the storage device 203 'are limited to the lines actually output from the decompression device 210', and which line is read is specified by the line information. The data to be read next may be pre-read in the memory 705 with reference to the line information. As a result, processing can be performed at a higher speed than in the above-described embodiment. As a configuration, a new read-ahead control unit 707 (not shown) is provided in the DMAC 209 ′, and the line information read control unit 7
The line information read under the control of 02 is input to the prefetch control unit 707. The prefetch control unit 707 refers to the line information and prefetches the data of the line whose flag indicates the output line into the memory 705. This look-ahead
Since the operation is performed in parallel with the operation of the pixel data read control unit 704, the processing speed can be further increased by the amount of pre-reading. Note that in this case, the memory 705 is desirably large enough to simultaneously store data of a plurality of lines in order to enhance the effect of prefetching. In addition, it does not prevent implementation with a smaller size. 4. Others Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, and the like), a device including one device (for example, a copier, a facsimile device, and the like) May be applied.

Since the object of the present invention is to increase the processing speed, it is more effective to configure the DMAC or the like only with hardware. Of course, the DMAC or the like may be realized by a combination of software and hardware. Therefore, an object of the present invention is to supply a storage medium (or a recording medium) in which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or an apparatus, and to provide a computer (or a CPU And MPU) read out and execute the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. When the computer executes the readout program codes, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instructions of the program codes. It goes without saying that a case where some or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing is also included.

Further, after the program code read from the storage medium is written into the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, the program code is read based on the instruction of the program code. , The CPU provided in the function expansion card or the function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

When the present invention is applied to the above-mentioned storage medium, the storage medium includes the above-described storage medium shown in FIGS.
Program codes corresponding to at least one or a plurality of flowcharts shown in FIG. 17 are stored.

[0075]

As described above, according to the present invention,
When decompressing the compressed binary image data, the time required for the image decoding process can be greatly reduced.

For example, in a typical horizontally written office document whose line spacing is equal to the height of a character, the processing time can be reduced to about half.

The present invention is not limited to the above-described image compression, but can be widely applied to information compression. For example,
The present invention is also effective when applied to compression and decompression processing of audio, video, text, and the like.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a document processing / creation system.

FIG. 2 is a diagram illustrating a configuration of a printer that is a basis of the embodiment.

FIG. 3 is a diagram illustrating a configuration diagram of a printer according to the embodiment.

FIG. 4 is a diagram illustrating an example of a typical office document according to the present embodiment.

FIG. 5 is a diagram illustrating a case where a bitmap of a character “A” is arranged on a page in the embodiment.

FIG. 6 is a diagram illustrating line information according to the embodiment.

FIG. 7 is a diagram showing an outline of a configuration of the present embodiment.

FIG. 8 is a diagram illustrating an outline of a process according to the embodiment;

FIG. 9 is a diagram illustrating a configuration example of a direct memory access controller according to the embodiment;

FIG. 10 is a flowchart at the time of JBIG encoding.

FIG. 11 is a diagram illustrating a two-line template in JBIG.

FIG. 12 is a diagram illustrating a three-line template in JBIG.

FIG. 13 is a diagram illustrating virtual pixel positions when using typical prediction in JBIG.

FIG. 14 is a diagram illustrating an inter-line coincidence detecting device.

FIG. 15 is a flowchart of an ENCODE process in JBIG encoding.

FIG. 16 is a diagram showing a flowchart at the time of JBIG decoding.

FIG. 17 is a flowchart of a DECODE process in JBIG decoding.

FIG. 18 is a view showing another embodiment 1 of the present invention.

FIG. 19 is a view showing another embodiment 2 of the present invention.

[Explanation of symbols]

 Reference Signs List 101 terminal device 102 input means such as keyboard 103 document processing software 104 document data 110 printer 111 printer controller 112 printer engine 200 host such as computer 201 host I / F 202 control device 203 storage device 204 memory controller 205 rasterizer 208 engine I / F 209 DMA controller 210 Compression / decompression device 220 Printer engine 200 'Host such as computer 201' Host I / F 202 'Control device 203' Storage device 204 'Memory controller 205' Rasterizer 208 'Engine I / F 209' DMA controller 210 'Compression / decompression device 220' Printer engine 401 Line information stored in storage device 203 '301 Control unit 302 Line Address register 303 skip counter 304 pixel address register 305 line information address register 306 bus interface 307 buffer 308,309 multiplexer 310 adder 311,312,313 incrementer. 501 Line information stored in the storage device 203 '

Claims (21)

[Claims] 1. A first storage unit for storing second information generated by compressing first information, and a plurality of information elements constituting the second information from the first storage unit A decoding means for sequentially reading out information elements satisfying a predetermined condition among the read information elements, and a second means for storing the information elements output from the decoding means.
Reading the information elements stored in the second storage means, and for the information elements not output to the second storage means, the predetermined information stored in the second storage means. An information processing apparatus, comprising: reading means for reading an information element; and an output device for outputting a series of information elements read by the reading means. 2. The decoding means determines whether a plurality of information elements constituting the second information read from the first storage means are common or similar to each other. The information processing apparatus according to claim 1, further comprising a determination unit, wherein when the determination unit determines that the plurality of information elements are common or similar, at least one of the plurality of information elements is decoded and output. An information processing apparatus according to claim 1. 3. The decoding means outputs information indicating that the output of the information element has been omitted for the information element that has not been decoded, and the reading means has determined that the output has been omitted. The information processing apparatus according to claim 2, wherein, based on the information, for an information element whose output has been omitted, an information element common or similar to the information element is read from the second storage unit. 4. The information processing apparatus according to claim 1, wherein the decryption unit further includes a creation unit that creates management information indicating whether or not each of the information elements has been output from the decryption unit. Referring to the management information created by the creating means prior to reading,
The information processing apparatus according to claim 3, further comprising a determination unit configured to determine whether the information element to be processed needs to be read. 5. The information element stored in the first storage means includes main information and sub information, and the main information is obtained by compressing a main component of the first information. And the sub-information includes information indicating a relationship between adjacent information elements, and the decoding unit, when decoding the information element, prior to decoding the main information. And decoding the sub-information, and wherein the judging means judges whether or not the plurality of information elements are mutually common or similar based on the decoded sub-information. An information processing apparatus according to claim 1. 6. The apparatus according to claim 1, further comprising third storage means for storing said management information, wherein said determination means reads said management information from said third storage means and makes said determination. 5. The information processing device according to 4. 7. The information processing apparatus according to claim 6, wherein said third storage means can read out data at a higher reading speed than said second storage means. 8. The information processing apparatus according to claim 1, wherein the first information is a binary image. 9. The method according to claim 1, wherein the first information includes a sound, an image, a moving image,
2. The information processing apparatus according to claim 1, wherein the information processing apparatus is a text or a data file. 10. The information processing apparatus according to claim 1, wherein a compression method used for information compression of the first information is a JBIG method. 11. The information processing apparatus according to claim 1, wherein said output means is an output interface to a printer, a facsimile, a display device, or a personal computer. 12. The information processing apparatus according to claim 1, wherein said output means is another information processing apparatus itself such as a printer, a facsimile, a display device, or a personal computer. 13. A decoding means for decoding compressed image data composed of a plurality of lines, a storage means for accumulating the relevance of the plurality of decoded lines, and If there is a relationship, a storage unit for storing at least one of the lines having a relationship, and a line of the decoded image data stored in the storage unit is read out from the storage unit and transferred to the outside. On the other hand, for an unstored line, a delivery unit that reads out data of another line based on the relevancy accumulated in the accumulation unit and transfers the data to the outside, and a delivery unit. 14. A first storage means for storing second information generated by compressing first information, and a plurality of information elements constituting the second information from the first storage means. A decoding means for sequentially reading out information elements satisfying a predetermined condition among the read information elements, and a second means for storing the information elements output from the decoding means.
Storage means for temporarily storing information elements read from the second storage means; and for the information elements stored in the second storage means, the second storage means The information element is read out from the storage means and once held in the holding means, and then the information element is read out from the holding means. For the information elements not stored in the second storage means, the information elements which are currently stored An information processing apparatus, comprising: a reading unit that reads an information element being read; and an output device that outputs a series of information elements read by the reading unit. 15. The information processing apparatus according to claim 14, wherein said holding unit can read data at a higher reading speed than said second storage unit. 16. The information processing apparatus according to claim 15, wherein a capacity of said holding means is equal to or larger than a capacity corresponding to a processing unit in said reading means. 17. Management information creating means for creating management information for managing which information element has been output to the second storage means, and based on management information created by the management information creating means. 15. The information processing apparatus according to claim 14, further comprising: a pre-reading control unit that causes the holding unit to pre-read an information element to be read by the reading unit in advance. 18. A step of storing second information generated by compressing information of the first information, sequentially reading a plurality of information elements constituting the second information, and Decoding only the information element that satisfies a predetermined condition, storing the decoded information element, reading out the information element that has been decoded and stored, and not storing the information element that has not been stored. Instead, reading the stored predetermined information element; and outputting the read series of information elements. 19. The decoding step includes: determining whether a plurality of information elements constituting the second information are common or similar to each other; and determining whether the plurality of information elements are common or similar. 19. The information processing method according to claim 18, further comprising the step of decoding and outputting at least one information element of the plurality of information elements when it is determined that they are similar. 20. The decoding step includes the step of outputting information indicating that the output of the information element has been omitted for the information element that has not been decoded, and the reading step includes omitting the output. 20. The information processing method according to claim 19, wherein the information element is a step of reading an information element common or similar to the information element based on the information indicating that the output has been omitted. Method. 21. The decoding step further comprises the step of creating management information as to whether or not each of the information elements has been decrypted. The reading step includes reading information elements to be processed. 21. The method according to claim 20, further comprising a step of determining whether or not it is necessary to read out the information element to be processed by referring to the management information created in the creation step in advance. Information processing method.