Grass Valley DD10 part 1 - Manual (Page 49)

2.7 Keyers Diamond digital DD10
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When should Luminance Key be used?
Luminance Key has always to be used when the key fill signal is not available on
a black background. A further application for Luminance Key is in the Coupled/Split
Key mode when the key signal does not match with the fill signal with regard to
contour (e.g. DVE key signals with soft border).
A so-called ”linear luminance key” (Lin Key) can be selected by simultaneously ac-
tuating the keys Add/Lin and Lum/Lin, thus achieving that the maximally possible
luminance value range is completely and ”linearly” reproduced on key signal value
range, regardless whether these extreme values also occur in the picture.
Actuating the Auto key achieves that the momentarily darkest luminance value is
reproduced on KEY=0 and the momentarily brightest value on KEY=1. Deviating
from that, the found adjustment can at any time be manually optimized by Clip/
Gain or Clean up/Density.
The new key processor II overcomes the traditional disadvantage of the Luminance
Key that in the Self Key mode, square-distorted edge shapes or erroneously eva-
luated levels are obtained. Now, a fill signal is generated which has been complete-
ly equalized. Thus is ensured that no dark edges are obtained at bright objects. Un-
proportional darkenings with plane luminance intermediates are not obtained
neither.
When, however, by adjustment of Clip and Density, deviating from adjustment of
Lin and Auto, a relatively dark luminance level is declared to be the foreground
level, this will of course also be reproduced, with the effect of fresh dark edges.