| 摘要 |
PCT No. PCT/FR78/00031 Sec. 371 Date Jun. 11, 1979 Sec. 102(e) Date Jun. 8, 1979 PCT Filed Oct. 11, 1978.In order to suppress interferences in the display of a picture composed of electronically generated image points or dots, such as that of a television receiver, luminance signals determining the brightness of dots occupying adjacent positions in the picture are compared and are modified in the presence of excessive contrasts before being fed to a brightness-control electrode of a cathode-ray tube. When a given luminance signal S(i,j), pertaining to an image point P(i,j) where i indicates the order number of a line in a scanning frame and j indicates the position of the point in that line, differs in absolute value by more than a predetermined threshold from a corresponding signal S(i-k,j-p) pertaining to at least one adjacent image point P(i-k,j-p), where k and p may have values +/-1 or 0, the signal S(i,j) is replaced by the signal S(i-k,j-p) incremented or decremented by a corrective signal Sc of predetermined magnitude, depending on whether signal S(i,j) is larger or smaller than signal S(i-k,j-p). The magnitude of the corrective signal Sc may be equal to the most frequently occurring contrast between adjacent image points according to a histogram which is either statistically predetermined or stored in a frame memory on the basis of quasi-instantaneous calculations performed on the actual signal levels.
|
