JPH031868B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention encodes image data such as drawings and text processed in a computer system using a run-length encoding method, transmits the encoded data, and displays the encoded data on a display or the like. The present invention relates to a code conversion method in which a run-length code is converted into a run-length code at high speed, and particularly to a run-length code conversion method for converting a run-length code into a run-length code at high speed.

(b) Technical background Recently, image data such as drawings and texts processed by computer systems are often transmitted and displayed on display devices using telephone lines, etc. In this case, facsimile devices are used. Image data is transmitted using run-length codes. Normally, when displaying the image data on a display, it is necessary to display it in a short time because the drawings and text are indexed, so a code conversion method that can perform the process of converting run-length codes into run-lengths at high speed is required. There is.

(c) Object of the Invention Based on the above-mentioned needs, an object of the present invention is to provide a run-length code conversion method for converting a run-length code into a run-length code at high speed.

(d) Structure of the Invention The structure of the present invention is a storage means configured such that the number of bits constituting a white or black run length and a run length code is read out in response to an address input in units of 13 bits. and a shift register which sequentially shifts the input run length codes in the order in which they were input and sends out the upper 13 bits as an address to the storage means each time the input run length codes are input, and the run length code read from the storage means. and control means for controlling the shift register to shift sequentially by the number of bits.

(e) Embodiments of the Invention A run-length code is a code used in facsimile transmission according to the recommendations of CCITT, and one line of data consists of a series of variable-length codes. Each code represents a white or black run length, with white run length codes and black run length codes occurring alternately.
Every data line begins with a white run length code, and if the actual scan line begins with black, a zero length white run length code is sent. Also, the run length code consists of a minimum of 2 bits and a maximum of 13 bits. Since this run-length code is transmitted as a continuous code string, the code structure is devised so that the boundary between the white run-length code and the black run-length code can be recognized.

In the present invention, since the white run length code is always transmitted as described above and the code has a maximum of 13 bits, each code of the white run length and black run length is stored in a code conversion memory whose address is 13 bits. A table in which the combinations are determined is stored, and based on the table, each run length and the number of bits of the code are stored in correspondence. By indexing this code conversion memory, run-length codes can be converted into run-lengths at high speed.

The figure is a block diagram of a circuit showing one embodiment of the present invention. A run length code is input from terminal A, and 8 is input to shift register 1 under the control of shift control unit 2.
They are divided into bits and written simultaneously. The shift control unit 2 sends a data request to shift the shift register 1 eight times from the terminal C, takes in the next 8 bits of data from the terminal A, and writes it into the shift register 1. Shift register 1 has a capacity of 16 bits,
When a 16-bit run-length code is written, a 13-bit run-length code is sent to the code conversion memory 3 from the first bit under the control of the shift control section 2. The run-length code sent from the shift register 1 to the code conversion memory 3 is checked in the code conversion memory 3. First, the first line of one page has EOL, followed by a white run length code, and then a black run length code, so EOL is read out from code conversion memory 3 to the D terminal in 13 bits. At the same time, 13 bits are sent to the shift control section 2, and the shift control section 2 shifts the shift register 1 by 13 bits. Therefore, the next 13 bits sent out from the shift register 1 include run length codes specifying the white run length, starting from the first bit, and these 13 bits are sent to the code conversion memory 3. Here, it is verified that a plurality of bits match from the first bit, and when a white run length code is detected at the beginning of one line, the run length corresponding to the code is sent from terminal D, and the run length at that time is The number of bits of the code is sent to the shift control section 2. The shift control unit 2 sends a data valid signal from terminal B,
At the same time, shift register 1 is shifted by the corresponding number of bits. Therefore, the shift register 1 can send the run-length code to the code conversion memory 3 from the first bit of the next run-length code.
This time a black run-length code is detected. By repeating the above operations, run-length codes can be converted into run-lengths at high speed.

(f) Effects of the Invention As explained above, the present invention is capable of converting a run-length code into a run-length at high speed, so that image data processed by a computer system can be displayed on a display or the like at high speed. Therefore, the effect is great.

[Brief explanation of the drawing]

The figure is a block diagram of a circuit showing one embodiment of the present invention. 1 is a shift register, 2 is a shift control section, and 3 is a code conversion memory.

Claims (1)

[Scope of Claims] 1. A storage means 3 configured so that the number of bits constituting a white or black run length and a run length code is read out in response to an address input in units of 13 bits; The shift register 1 sequentially shifts the run-length codes inputted in the order in which they are input, and sends out the upper 13 bits as an address to the storage means 3 each time the shift is performed, and the run-length code read from the storage means 3. Control means 2 for controlling the shift register 1 to shift sequentially by the number of bits.
A run-length code conversion circuit comprising: