Television – Image signal processing circuitry specific to television – Noise or undesired signal reduction
Patent
1994-01-14
1997-04-29
Peng, John K.
Television
Image signal processing circuitry specific to television
Noise or undesired signal reduction
348619, 348452, 348448, 348911, H04N 521
Patent
active
056254210
ABSTRACT:
Jagged vertical or diagonal transition artifacts in interlaced to line doubled progressive scan converted television signals are detected and areas of the television picture having such artifacts are subjected to vertical averaging such that the resolution of the jagged transitions is reduced, thereby softening, "greying" or "fuzzing" the jagged transitions and causing them to appear smooth. Thus, highly contrasted lines appearing in a sawtooth pattern, which are extremely perceptible, are replaced with a flash of what might be characterized as "fuzziness," which is not perceptible. The eye no longer perceives the jagged artifacts. Moreover, areas of reduced vertical and horizontal resolution, resulting from the vertical averaging, do not create any new artifacts and are not perceived by the eye. Artifacts are detected by comparing pixels in corresponding positions in the scan lines of the line doubled progressively scanned television signal. The detection scheme looks for sawtooth patterns by determining if there are differences among pixels in more than one set of three adjacent lines. When a sawtooth pattern is detected, the uncorrected signal in the sawtooth region of a scan line is faded to a vertically filtered or averaged signal just prior to the onset of the sawtooth artifact region and then faded back to the uncorrected signal just subsequent to the sawtooth artifact region. The sawtooth correction signal, which controls fading to and from a filtered video signal, is expanded in all directions horizontally and vertically somewhat beyond the region of the detected artifact in order to insure that all of the artifact is suppressed.
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Faroudja Yves C.
Swartz Peter D.
Faroudja Yves C.
Flynn Nathan J.
Gallagher Thomas A.
Peng John K.
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