| 摘要 |
<p>RCA 72,007 First l-H type comb filter provides an output representative of the sum of current line video signals and preceding line video signals, which is delivered to an adder via a wideband signal path, as a wideband combed luminance signal input occupying a given band of frequencies. Second 1-H type comb filter provides an output representative of the difference between current line video signals and preceding line video signals which is delivered to said adder, via a signal path with a pass band restricted to only a low frequency portion of the given band, as a restricted band vertical detail signal input. Latter signal path translates at least portions of said vertical detail signal with a gain which is enhanced relative to the gain with which said combed luminance signal components are translated by said wideband signal path, and delivers said difference representative output with such polarity that the current line video signal contribution to said difference appears at the adder with the same polarity as the constituents of the sum representative output delivered thereto. The adder output forms a luminance signal with an asymmetrical form of vertical peaking in which overshoots only appear at transitions in the direction of vertical scanning of the black-to-white type, and undershoots only appear at transitions in the direction of vertical scanning of the white-to-black type.</p> |
