KR930003201B1 - Bit image data compressing method and apparatus - Google Patents

Abstract

The apparatus and method maintains data compressing ratio regardless of the type of bit image data by replacing 8x8 window by a code which is determined by a frequency of 1's in an 8x8 window. The method comprises the steps: (A) reading data in a bit image memory (100) by block units and storing the data on a block memory; (B) outputting the block data in series using a parallel to series converter (300); (C) transmitting the serial data to a counter; (D) counting the number of 1's in the serial data; (E) checking that a certain number of data is received by a counter; (F) storing a code transmitted from a counter according to the number of 1's on a compressed data memory (500); and (G) checking that all data is read from a bit image memory (100).

Description

Bit image data compression method and apparatus

1 is a schematic diagram of a conventional image pressure system.

2 is a block diagram of an image input system employing a bit image data compression apparatus according to the present invention.

3 is a flowchart illustrating a method of compressing bit image data according to the present invention.

4 is a block diagram of an apparatus for performing the bit image data compression method according to FIG.

5 is a decoding code table of a compressed signal according to the present invention.

* Explanation of symbols for main parts of the drawings

10: CCD 20: amplifier

30: sample / holder 40: analog / digital converter

50: Binarizer 70a, 70b: Bit image data compression device

80: data storage and transmission unit 100: bit image memory

200: block memory 300: parallel / serial converter

400: count compressor 500: compressed data memory

600: address generator 700: control unit

430, 440, 710: inverter

The present invention relates to a method for compressing bit image data and a device thereof, and more particularly to a method for compressing bit-substituted data in order to increase the transmission speed when storing or transmitting data efficiently in an image input system. And to the apparatus.

In general, an image input system using a data compression method used for an image scanner, a CCTV camera, a facsimile, and the like is shown in FIG. In FIG. 1, the analog signal through the Charge Coupled Device (CCD) 10 is amplified by the amplifier 20 constituting the data input unit and the sample / holder 30 and the analog / digital device. Digitized via the converter 40 and then converted by the binarizer 50 to binary image (or bit image) data having values of "0" and "1".

On the other hand, the data compression unit 60a stores and compresses the data according to the frequency of occurrence of the binary image (or bit image) data transmitted from the binarizer 50, thereby causing the data storage and transmission unit 70 to store the data. Allow to save or output data through the transmission line.

As described above, coding used for an image scanner, a CCTV camera, and a facsimile is performed by using typical characteristics of the pixel configuration. In other words, MH (Modified Huffman) coding is used as a typical compression method for the compression method according to the number of times "1" and "0" are repeated (Reference, Huffman code configuration In the form, the value of the coded encoded data is given as 64 × n + α, where n is the make-up code, and if there are more than 64 repetitions of "1" or "0", there is 1 for every 64. Causes α to represent one-dimensional Huffman code). Therefore, the data compression unit 60a does not have any drawbacks in performing the data restoring force. However, the data compression unit 60a compresses the data based on the frequency of data generation. That is, the compression method sequentially counts the number of " 1 " and " 0 " for each line and transmits the corresponding code value so that the receiving end decodes the code value transmitted from the code table to produce the corresponding bit pattern. In general, if the compression of a photograph or a dithering or halftone image with a complex background is good, the compression of the bit image is severe. More binary images appear. For example, if a pattern in which a bit image is repeated continuously such as "1" and "0" such as "10101010" occurs frequently throughout Mars (especially in a halftone image, this phenomenon is remarkable) and "1" and Since the "0" is repeated more times, the code value corresponding to the bit image becomes longer, which takes up more memory space.

In addition, the apparatus of the data compression unit 60a using the method of checking and compressing the number of data repetitions in byte unit also has a small number of times that "1" and "0" are repeated if the configuration of the input image is simple, and the amount of transmission is repeated. On the contrary, when the configuration is small and complicated, the number of repetitions increases, such that the amount of transmission is increased. Accordingly, an object of the present invention is to solve the above problems and to detect bit frequency data received by the image input apparatus and detect the frequency of " 1 " in an 8x8 window and replace the code with a corresponding code value. To provide a bit image data compression method and apparatus for maintaining a constant compression rate of a constant.

Bit image data compression method according to the present invention for achieving the above object, the first step of reading the data corresponding to a predetermined block from the bit image memory and stored in the block memory, and the predetermined block data in the first step After all the data are stored in the block memory, the block memory is put into a read mode, and the parallel / serial converter is enabled to output the block data in series, and the parallel / serial converter is performed after performing the second step. A third step of inputting the passed bit image data to the clock terminal of the constant bit count compressor; and after performing the above three steps, " 1 " A fourth step of counting the number and a predetermined number of ratios to the predetermined number of bit count compressors after performing the fourth step. A fifth step of determining whether image data has been input; and if the predetermined number of bit image data has not been input in the fifth step, returns to the third step and writes the compressed data memory when the predetermined number of bit image data has been inputted. Write) mode, and if the write mode is operated in the sixth step, the data value of a predetermined bit output from the count compressor of a predetermined bit is stored as a compressed code value and the count compressor of the predetermined bit is cleared. The seventh step of activating the stage to make the output of the count compressor " 0 " and whether there is any image data to be compressed to read a predetermined value of block image data from the bit image memory after performing the seventh step. If it is determined that image data remains, the process returns to the first step and no further If the kinds of data, characterized by configured by comprising an eighth step which is terminated.

In addition, the bit image data compression apparatus of the present invention for performing the bit image data compression method includes a bit image memory for storing bit image data passed through a data input unit, and data of a predetermined block transferred from the bit image memory. A block memory for storing and performing a read mode, a parallel / serial converter for storing all block data in the block memory and enabling the block data to be serially output, and bit image data passing through the parallel / serial converter. And a predetermined bit count compressor for counting the number of " 1 " present in the bit image data by inputting the clock terminal to the clock terminal. Bit data output from A compressed data memory for storing a value as a compressed code value, an address generator for generating an address to store data corresponding to a predetermined block from the bit image memory in a block memory, and the bit image memory and a constant bit counter compressor. And a control unit for transmitting the control signal to the controller and inverting the control signal to the block memory through the inverter.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 2 is a configuration diagram of an image input system employing a bit image data compression apparatus according to the present invention. 3 and 4 are flowcharts illustrating a bit image data compression method according to the present invention, and a block diagram of an apparatus for performing the compression method.

2 and 3 and 4, the bit image data compression method according to the present invention reads data corresponding to 8x8 blocks from the bit image memory 100 and stores them in the block memory 200. When all of the 8 × 8 block data is stored in the block memory 200 in the first step (1) and the first step (1), the block memory 200 is placed in read mode and the parallel / serial converter 300 is turned on. 6-bit count compressor 400 for bit image data passed through parallel / serial converter 300 after performing the second step (2) of enabling and outputting block data in series and enabling the second step (2). And a fourth step of counting the number of " 1 " present in the bit image data input to the clock terminal of the 6-bit count compressor 400 after performing the third step. 6 bits after performing step (4) and the fourth step (4) The count compressor 400 of FIG. 5 determines whether the 64th bit image data is input by the control unit 700. In the fifth step 5, the 64 bit image data is 6 bits. The sixth step (6) of returning to the third step (3) if it cannot be inputted to the count compressor 400 of the operation, and operating the compressed data memory 500 in the write mode if the 64-bit image data is inputted. When the write mode is operated in the sixth step (6), the 6-bit data value output from the 6-bit count compressor 400 is stored as a compressed code value and the clear stage of the 6-bit count compressor 400 is clear. Is activated so that the output of the count compressor 400 becomes " 0 " and the 8x8 block image from the bit image memory 100 after performing the seventh step (7). Image to compress to write data If it is determined whether the data remains and the image denier remains, the process returns to the first step (1). If there is no image data to be compressed, the process is terminated as is and the eighth step (8) is configured.

Meanwhile, an apparatus for executing the bit image data compression method includes a bit image memory 100 for storing bit image data passed through a data input unit and an 8 × 8 block transmitted from the bit image memory 100. A block memory 200 for storing read data and performing a read mode, and a parallel / serial converter 300 for outputting block data in series by enabling block data 200 when predetermined block data is stored in the block memory 200; The two counters 410 and 420 and the inverters 430 and 440 input the bit image data passed through the parallel / serial converter 300 to the clock terminal to count the number of " 1 " present in the bit image data. 6-bit count compressor 400, and when the 64-bit image data is input from the constant bit count compressor 400, the 6-bit count compressor 400 operates in the write mode. Compressed data memory 500 for storing 6-bit data and values output from the und compressor 400 as compressed code values, and data corresponding to 8x8 blocks from the bit image memory 100 are block memories. The control signal is transmitted to the address generator 600 generating the address to be stored in the 200, the bit image memory 100 and the 6-bit count compressor 400, and the block memory 200 through the inverter 710. And a control unit 700 for inverting and transmitting the control signal.

Referring to the operation and effects of the present invention having the configuration as described above are as follows. 2 and 3 and 4, the bit image data compression method and apparatus according to the present invention divide the entire image data input through the CCD 10 shown in FIG. If a code value suitable for the image existing in each block is detected, stored, and transmitted, the restoration side (not shown here) reproduces a specific bit image pattern corresponding to the code value. First, the amplifier 10, the sample / holder 30, the analog / digital converter 40, and the binarizer 50 constituting the CCD 10 and the data input unit shown in FIG. With respect to the bit image data stored in the bit image memory 100 of FIG. 3 constituting the bit image data compression device 60b according to the present invention, the control unit 700 controls the bit image data described above via the address generator 600. Step (1) is performed to read data corresponding to 8x8 blocks from the memory 100 and store the data corresponding to the 8 × 8 block in the block memory 200. In this case, the control unit 700 uses the inverter 710 to control the bit image memory 100 and the block memory 200 at the same time even if the R / W signal is transmitted only once. Allow the W signal to be input.

When the 8 × 8 block data is all stored in the block memory 200 by the above operation, the block memory 200 is put into read mode and the parallel / serial converter 300 is enabled to sequentially output all block data in a serial state. Perform step (2) if possible. After performing step (2), the bit image data passing through the parallel / serial converter 300 is input to the clock terminal CLK of the 6-bit count compressor 400 composed of two counters 410 and 420. Step 4 is performed to count the number of " 1 " present in the bit image data.

The 6-bit count compressor 400 performs step (5) of determining whether the 64th bit image data is input by the controller 700, and the 8x8 block memory 200 and the parallel / serial converter. When all 64 bits of image data through 300 are input, step 6 of operating the compressed data memory 500 in the write mode is performed. When the compressed data memory 500 is operated in the write mode by performing the step (6), the 6-bit data value output from the 6-bit count compressor 400 is stored as a compressed code value. Step 7 of activating the clear (CLK) stage of the counters 410 and 420 constituting the count compressor 400 to make the output side of the 6-bit count compressor 400 "0" is performed. At this time, the control unit 700 reads the 8 × 8 block data into the block memory 200 through the address generator 600 to write 8 × 8 block image data from the bit image memory 100 again. Are repeated, and if the bit image data cannot be compressed, step 8 is terminated as is. On the other hand, Fig. 5 shows an image pattern which is recovered according to the frequency of 8x8 block " 1 " as a decoding code table of the compressed signal according to the present invention.

In order to perform the present invention as described above, the resolution of the image input system is 300dpi or more, which is a good effect. If the method of the present invention is less than 200dpi, the image quality may be degraded. According to the process of performing the above steps, the compressed data can be converted into 64-bit at least 6-bit or 8-bit compressed data, so that the compression ratio can always be maintained at 1/8 or more. Playback is performed with the 8x8 bit image pattern of FIG. 5 as promised.

As described above, the present invention can obtain a constant data compression ratio, and has a dithering pattern, which has the effect of softening the original image, and can predict the amount and shape of the output signal by the image input system. There is an advantage that the amount of source data cannot be exceeded.

Claims (5)

A first step of reading data corresponding to a predetermined block from the bit image memory 100 and storing the data corresponding to the predetermined block in the block memory 200; and the predetermined block data is stored in the block memory 200 in the first step. A second step of outputting the block data in series by putting the memory 200 in the read mode and enabling the parallel / serial converter 300, and then performing the parallel / serial converter 300 after performing the second step. The third step of inputting the bit image data passing through the) into the clock terminal of the count compressor 400 of the predetermined bit, and the bit image input to the clock terminal of the count compressor 400 of the predetermined bit after performing the above three steps A fourth step of counting the number of " 1 " present in the data; and determining whether a predetermined number of bit image data has been input to the constant-count bit compressor 400 after performing the fourth step. In the fifth step, if the predetermined number of bit image data has not been input in the fifth step, the process returns to the third step. If the predetermined number of bit image data is input, the compressed data memory 500 is placed in the write mode. When the write mode is operated in the sixth step and the sixth step, the compressed code value of the data value of the predetermined bit output from the count compressor 400 of the predetermined bit is stored and the count compressor 400 of the predetermined bit is stored. The clear seek determines whether image data remains in order to write a predetermined value of block image data from the bit image memory 100 after performing the seventh step and the seventh step. And the eighth step of returning to the step and ending if there is no image data. Unknown data compression method. 2. The method of claim 1, further comprising: classifying image data formed by reading an image in units of N × N bit blocks, counting a number of predetermined logical values in the data in the divided blocks, and counting outputs of the predetermined logical values. And storing and transmitting a predetermined block of NxN bits corresponding to the stored and transmitted counting outputs. A CCD 10 for converting light into an electrical signal, a data input unit for digitally converting and storing an analog signal converted from the CCD 10 into an electrical signal, and data storage for storing or transmitting compressed data And a decoding unit for reproducing an image pattern stored by a compressed data code, comprising: a bit image memory (100) for storing bit image data passed through a data input unit; A block memory 200 which stores data of a predetermined block from the image memory 100, a parallel / serial converter 300 which converts and outputs predetermined block data of the block memory 200 in series, and the parallel / serial A count compressor 400 which inputs bit image data passing through the converter 300 to a clock terminal and counts the number of " 1 " present in the bit image data; The compressed data memory 500 stores the data value of the predetermined bit output from the count compressor 400 as a compressed code value, and the data corresponding to the predetermined block from the bit image memory 100 are stored in the block memory ( An address generator 600 for generating an address to be stored in the 200, and a control unit 700 for controlling the beam and read operation of each of the memory (100) 200 and 500 and the counting operation of the count compressor 400 Bit image data compression apparatus characterized in that it comprises a. 4. The bit image data compression apparatus as claimed in claim 3, wherein the count compressor (400) comprises two counters (410, 420) connected in parallel. 4. The bit image data compression apparatus as claimed in claim 3, wherein the block memory (200) comprises blocks of 8x8 bits in a storage unit.

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