SU605335A2 - Arrangement for coding and decoding screened image video signal - Google Patents

Description

one

The invention relates to radio engineering and can be used in the transmission of screened images, such as illustrations of newspapers.

According to the main author. St. No. 488360, a device for encoding and decoding video signals of rasterized images is known, comprising, on the transmitter side, a subtraction unit, a selector, a delay unit, and a code-block unit, and on the receiving side a decoding unit, two delay units, a subtraction unit, a prohibition element, and a symmetric trigger; between the coding block on the transmitting side and the decoding block on the receiving side, the communication channel is switched on.

However, the known device has a low transmission rate due to the presence of pulses in the video signal that are different in duration from neighboring ones in monochromatic areas of the image.

The aim of the invention is to increase the transmission rate.

To do this, the device for encoding and decoding video signals of rasterized images, contains on the transmitting side a subtracting unit, a selector, a delay unit and a coding unit, and on the receiving side a decoding unit, two delay units, a subtracting unit, a prohibition element and a symmetric trigger, between the encoding unit at the transmitting side and the decoding unit at the receiving side, the communication channel is switched on; a rasterization period equalizer is inserted at the transmitting side, the output of which is connected to the input of the subtraction unit neither the input of the selector and the input of the delay unit, and the delaying period corrector contains two delays connected in series, the output of each of which is connected respectively to the first and second inputs of the controlled switch, the third input of which is connected to the output of the decision block, the first and second inputs of which are connected respectively, with the input of the first delay line and the output of the second delay line, the video signal is fed to the input of the first delay line, and the output of the controlled switch is the output of the corrector Ktorov periods scan conversion.

The drawing shows a structural electrical circuit of the proposed device.

A device for encoding and decoding video signals of the raster image contains, on the transmitting side, a block I subtract, a selector 2, a block 3 delay and a block 4 encoding, and on the receiving side a block 5 decoding, two blocks b and 7 delay, block 8 subtraction, prohibition element 9 and symmetric trigger 10, while between

the encoding unit 4 on the transmitting side and the decoding unit 5 on the receiving side enabled communication channel 11. The device also contains on the transmitting side a corrector for 12 periods of rasterization, the output of which is connected to the input of the subtraction unit 1, the input of the selector 2 and the input of the delay unit 3, and the corrector 12 contains two series-connected delay lines 13 and 14, the output of each of which is connected respectively to the first and second inputs of the controlled switch 15, the third input of which is connected to the output of the decision block 16, ne The second and second inputs are connected respectively to the input of the first delay line 13 and the output of the second delay line 14, the video signal is fed to the input of the first delay line 13, and the output of the controlled switch 15 is the output of the equalizer 12, the input of the first delay line 13 is input 1M corrector 12.

The device works as follows.

When analyzing a line with raster dots is formed. video signal, which is a sequence of pulses corresponding to the black points of the image. The video signal is processed in an equalizer 12 rasterization periods. In the corrector 12, the impulse corresponding to a point that appears to be different from its neighbors due to the imperfection of the printing technology is equalized in duration with the adjacent right and left pulses. After such a conversion, a signal containing a smaller number of transitions is fed to the input of coding unit 4.

As a result, the total number of transmitted code combinations decreases, the efficiency of the device increases (the transmission rate increases).

Claims (2)

1. Device for encoding and decoding video signals of rasterized images by author. St. No. 488360, characterized in that, in order to increase the transmission speed:, a rasterization period corrector is inserted on the transmitting side, the output of which is connected to the input of the subtracting unit, the input of the selector and the input of the delay unit. 2. The device according to claim 1, characterized in that the offset rasterization period contains two series-connected delay lines, the output of each of which is connected respectively to the first and second inputs of the controlled switch, the third the input of which is connected to the output of the decisive unit, the first and second inputs of which are connected respectively to the input of the first delay line and the output of the second delay line, moreover to the input of the first delay-line the video signal, and the output of the controlled switch is the output of the rasterization period offset. VC. H-EIHZh