System for encoding and decoding video signals.

摘要

In a raster scanned television system a high degree of correlation exists both in the luminance (L) and in the chrominance signals (H, S) of a pair of adjacent lines (11, 12, etc.). Because of this correlation, the difference between the luminance signals (L) of the two lines (11, 12, etc.) is much smaller than luminance signal (L) of either line (11, 12, etc.) alone, it has less bandwidth. A luminance carrier is amplitude modulated by the average value of two adjacent lines (11, 12, etc.), while the phase of the carrier is modulated by the difference of two adjacent lines (11-12, 13-14, etc.). The bandwidth of the resulting signal is comparable to that of a carrier that is amplitude modulated by a single raster line (11, 12, etc.). Since two lines (11, 12, 13, etc.) of information are being transmitted, however, it would be possible to take twice as much time to transmit them as when only a single line (11, 12, 13, etc.) is being transmitted. Stretching the time axis in this way results in about a factor of about two reduction in bandwidth. A simple average of chrominance signal (H, S) is used for both hue (H) and saturation (S). A chrominance carrier is amplitude modulated by the average value of two adjacent hue lines (11, 12, 13, etc.), while the phase of the carrier is modulated by the average of two adjacent color saturation lines (11, 12, 13, etc.). After synchronous demodulation of the carriers, inverse operations are utilized to reconstitute the luminance (L) and chrominance signals (H, S).