Showing papers on "Video quality published in 1981"

Picture information coding method

Abstract: PURPOSE:To make coding the information including the halftone, by grasping the video element for the part from each video element information consecutive sequentially through multivalue sampling of picture dissolving into video element unit and executing the optimum coding according to the video quality. CONSTITUTION:The video signal read in the video element unit at the scanner is made to N-value quantization at the quantizing unit 1, and this quantized signal is fed to the delay circuit 2 for one video element's share and the differential unit 3. The difference between the concentration level of delayed video element with this differential unit 3 and that of the noticed video element is detected and the difference is fed to the coding table 4 and the output of the quantizing unit 1 is directly fed to the table 4. At this table 4, the concentration level of the first video element of the unit block from the quantizing unit 1 is coded with the combination of binary code from a given rule, and when the concentration level value of the video element consecutive is minumum or maximum level, run length coding is made, and when the concentration level is at halftone level, the differential coding is made and the result is fed to RAM5 of the reception side II.

Playback device for color video signal

Abstract: PURPOSE:To playback color video signal in excellent manner, by preventing the deterioration of video quality, by changing the cancellation of components 2 times the carrier frequency in response to the level of playback carrier chrominance signal. CONSTITUTION:Luminance signal is in angular velocity modulation, and charrier chrominance signal is in frequency-conversion to low band, and the subcarrier frequency is selected to be 1/4 line offset and reproduced for the recorded color video signal. The output of a frequency demodulator 5 is fed to a subtractor 16 as it is, and the demodulated output delayed by 1 horizontal period is fed to the subtractor 16 through the delay circuit 15 for one horizontal period. Further, the luminance signal which has no vertical correlation with the components 2 times the frequency of the carrier frequency is fed to a limiter 18 through an amplifier 17 to suppress the luminance signal without vertical correlation and to pick up 2 times frequency components to be fed to a subtractor 19. The luminance signal cancelling double frequency component from the subtractor 19 is fed to a synthesizer 20, it is mixed with the playback charrier chrominance signal from BPF8, and the deterioration of playback video quality can be avoided.