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CPP100
SECTION 9
CPP1OPS
25/10/06
www.snellwilcox.com
Version 1 Issue 6
9.21
Enhancer cont.
Mode - Decoder Matching
The aim of decoder matching is to reduce the artefacts produced by composite decoding. This is done by
applying filters that complement the comb filters in the decoder to produce a larger overall aperture.
A composite comb decoder will use a spatial or a vertical/temporal aperture to separate luminance from
chrominance. With knowledge of the comb structure the decoder matching filters in Prefix filter areas of the
spectrum which have not been previously filtered by the composite decoder. Cross-effects such as cross-
colour (high frequency luminance in chrominance) and cross luminance (residual chrominance in luminance)
are reduced in amplitude.
The line comb setting is used for decoders which utilise a line comb structure for Y/C separation. The Field
Comb setting is used for decoder which utilise a field comb structure based on 312H (PAL) or 263H (NTSC)
diagonal vertical/temporal filters such as the Prefix internal field comb decoder.
For simple or notch decoders which do not utilise a comb decoder strategy for Y/C separation or where the
Y/C separation strategy is unknown, the
Other
setting provides good suppression of high frequency diagonal
components which may have originated from cross-effects.
Luminance Decoder Matching
Chrominance decoder matching
delay
delay
Complementary
Filter
Horizontal
bandpass
filter
centre tap
centre tap
taps
taps
Complementary
Filter