JP2001111844A - Coding processing method and coding processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coding processing device that attains coding processing at a higher speed. SOLUTION: In parallel with coding processing of a just preceding line, image data by a newest line received by a 1st line memory are compared with image data by one just preceding line received by a 2nd line memory. Then the image data are coded based on the result of comparison.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoding processing method for encoding image data using a plurality of line memories connected in series.

[0002]

2. Description of the Related Art Conventionally, as a compression coding method of image data used for facsimile communication or the like, MH (Modified
Huffman) method, MR (Modified Read) method, MMR
(Modified Modified Read) method was used. M
The H method is a method of encoding the number of continuous white or black pixels, and is a one-dimensional compression encoding method in which each scanning line is compressed. The MR method is a compression coding method in which the efficiency is improved by utilizing the correlation between two scanning lines (lines) in the vertical direction, that is, adjacent to each other. The MMR system is a system in which the compression efficiency is further improved by partially improving the MR system, and is in principle the same as the MR system. Each of the MH, MR, and MMR systems is a reversible system, that is, a system that can restore 100% to the original state.

On the other hand, with the development of computer technology, especially digital image technology in recent years, various image compression coding systems have been desired and developed. Among them, as a reversible method, that is, a method capable of 100% restoration to the original state, a so-called JBIG (Joint Bi-level Image coding expert Grou
p) method is ITU-T (International Telecommunication
on Union-Telecommunication recommendation). 82 as a standard for applying it to facsimile communication. 85
Is stipulated.

[0004] By the way, in encoding by the JBIG method, an image to be encoded is divided into a plurality of sub-scanning lines (lines) and divided into sections called stripes. The binary image data (dot data) directly obtained from each stripe is encoded according to the correlation between the target pixel, the line where it is located, and one or two lines immediately before the target pixel in a predetermined range. Into SCD (striped encoded data). Further, the SCD is converted into PSCD (protected stripe coded data) by a predetermined process. Then, an end marker indicating the end of one stripe of data is added to the PSCD, and an SDE (striped data entity) is generated. FMS (floating marker segment) is added to each SDE, and BID (binary image data) of one image is used by using a plurality of sets.
To form Further, the BID is added with a BIH (binary image header) recording various parameters when the BID is generated, thereby forming a BIE (binary image entity).

[0005] In the encoding process of the JBIG system, encoding is performed using two lines of pixels including a line including a pixel to be encoded and a line immediately before the line. In some cases, encoding is performed using pixels of three lines. When typical prediction of the lowest resolution layer is performed (TPBON), exception processing is performed when the line including the pixel to be encoded matches the line immediately before. That is, SLNT is added to the beginning of all lines.
P data is added, and if they match, SLNTP
Only data is encoded, and if they do not match, SLNT
Encode the entire line containing the P data. Conventionally, in order to realize such processing, a line buffer for three lines is prepared, and data read from the line buffer is compared. After the comparison between the line including the pixel to be encoded and the line immediately before the line is completed, the encoding process according to the result is performed.

[0006]

In the above-described conventional method, the encoding processing unit is stopped while comparing the lines. Further, two reading operations are required at the time of comparing data stored in the line memory and at the time of encoding. Such a procedure has been one of the obstacles to speeding up the encoding process.

[0007] The present invention has been made in view of the above situation, and has as its object to provide an encoding method and an encoding apparatus which contribute to speeding up of encoding processing.

[0008]

In order to solve the above-mentioned problems, in an encoding processing method according to the present invention, input image data is stored in units of lines, and at the same time, a target pixel to be coded before being stored is included. The line data to be encoded is compared with the line data immediately before. Then, encoding processing of the input image data is performed based on the result of the comparison.

Further, an encoding processing device according to the present invention includes a line memory for holding input image data in line units;
Comparing means for comparing the line data to be encoded including the pixel to be encoded before being held in the line memory with the immediately preceding line data; and performing encoding processing of the input image data based on the result of the comparison by the comparing means. Encoding processing means.

In the present invention as described above, line comparison is performed using the line data to be encoded before being held in the line memory. Therefore, the encoding processing of the immediately preceding line and the line comparison processing can be performed in parallel. Further, it is not necessary to read the data for comparison from the line memory each time. As a result, it is possible to further speed up the encoding process.

[0011]

FIG. 1 shows the configuration of an encoding apparatus according to an embodiment (embodiment) of the present invention. This encoding processing device includes line memories 12a, 12b, 1 that hold image data supplied from an image bus 10 in line units.
2c, a line coincidence detecting unit 14, and an encoding processing unit 16. The line memories 12a, 12b, 12c are connected in series. The image bus 10 is connected to an input terminal of the line memory 12c and one input terminal of the line coincidence detecting unit 14. The output terminal of the line memory 12c is connected to the encoding processing unit 16, the input terminal of the line memory 12b, and the other input terminal of the line coincidence detection unit 14.

The output terminal of the line memory 12b is connected to the encoding processing unit 16 and the input terminal of the line memory 12a. The output terminal of the line memory 12a is connected to the encoding processing unit 16. An output terminal of the line coincidence detecting unit 14 is connected to the encoding processing unit 16. The line coincidence detecting unit 14 compares the pixel value of a line including an encoding target pixel (hereinafter, referred to as “encoding target line”) with the pixel value of the immediately preceding line, and outputs a signal corresponding to the comparison result to the encoding processing unit 16. To supply. The encoding processing unit 16 performs an encoding process based on a signal from the line coincidence detection unit 14. In other words, the encoding processing unit 16 performs different processing depending on whether the pixel value of the line to be encoded and the pixel value of the immediately preceding line completely match or different even by one pixel.

FIG. 2 shows the configuration of the line coincidence detecting section 14. In the line coincidence detection unit 14, the line memory 1
2c and data of the same number of pixels from the image bus 10 and exclusive-ORed data for one line are collected and "l
and ntp _y ". Here, the number of pixels read at a time is
Line memory (12a, 12b, 12c) and image bus 1
0 is determined. The circuit configuration other than the number of generations of the read signal of the line memory 12c and the image bus 10 does not depend on the number of pixels read at one time.

One of the JBIG coding modes uses typical prediction. In this case, assuming that _y is a line to be encoded, if the y line and the line immediately before (y-1 line) match, lntpy = 0, and if even one pixel does not match, , lntp _y = 1
Becomes Slntp _y is defined by the equation of FIG.

[0015] As shown in FIG. 3, Slntp _y is placed at the beginning of the y line. For this reason, the image to be encoded has a width one pixel larger than the original image. If the result of the comparison by the line coincidence detecting unit 14 shows that the line to be encoded and the line immediately before it match, the encoding processing unit 1
In 6, encodes only Slntp _y, and terminates the encoding of the line. On the other hand, if even one pixel does not match as a result of the comparison in the line match detection unit 14,
The encoding processing unit 16, after encoding the Slntp _y,
All pixels for one line are encoded. As described above, the processing method differs depending on whether the line including the encoding target pixel completely matches the previous line or not. Since Slntp _y is placed at the beginning of the line, in this embodiment, to detect whether the line before match to start processing of the line that contains the coded pixel.

The embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments, but can be modified within the scope of the technical idea described in the claims. is there. That is, the present invention can be applied to all encoding systems in which data comparison is performed for each line when encoding image data, and the subsequent processing is determined by the result. In the case of performing the process by comparing two lines, it is sufficient to provide two line memories.

[0017]

As described above, according to the present invention,
The line data to be encoded before being held in the line memory is compared with the line data immediately before. Therefore, the encoding processing of the immediately preceding line and the line comparison processing can be performed in parallel. Further, it is not necessary to read data for comparison from the line memory. As a result, it is possible to further speed up the encoding process.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of an encoding processing device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a line coincidence detection unit used in the embodiment illustrated in FIG. 1;

FIG. 3 is an explanatory diagram for explaining an operation of the embodiment;

[Explanation of symbols]

 12a, 12b, 12c Line memory 14 Line match detection unit 16 Encoding processing unit

Claims (4)

[Claims] A step of holding input image data in units of lines; a step of comparing line data to be encoded including the pixels to be encoded before being held with line data immediately before; Encoding the input image data based on the result. 2. A first line memory for holding encoding target line data including an encoding target pixel in input image data, and a second line for holding line data output from the first line memory. In an encoding processing method for performing encoding processing of image data using a memory, a pixel included in the encoding target line data before being input to the first line memory; An encoding processing method, comprising: comparing pixels included in line data immediately before input; and encoding the input image data based on a result of the comparison. 3. A line memory for holding input image data on a line-by-line basis; comparing means for comparing line data to be encoded including a pixel to be encoded before being held in the line memory with immediately preceding line data Encoding processing means for encoding the input image data based on the result of the comparison. 4. A first line memory for holding encoding target line data including an encoding target pixel in input image data; and a second line for holding line data output from the first line memory. A memory; a pixel included in the line data to be encoded before being input to the first line memory and a pixel included in the line data immediately before input to the second line memory completely match A coding means for performing a coding process on the input image data based on a detection result by the comparing means.