Video signal luminance and chrominance separation

Details Video signal luminance and chrominance separation Video signal luminance and chrominance separation

1999-05-17

2001-12-25

Luu, Matthew (Department: 2672)

Television

Image signal processing circuitry specific to television

Chrominance-luminance signal separation

C348S607000, C348S609000, C348S665000, C348S667000

Reexamination Certificate

active

06333764

ABSTRACT:

The invention relates to an improved method and apparatus for separating composite colour video signals into separate luminance and colour components. It applies to colour encoded signals in which the colour information is amplitude modulated on a high frequency subcarrier. Such systems include NTSC and various forms of the PAL system.
Many forms of comb filters have been described which when incorporated in a colour television decoder provide improved separation of the luminance and colour difference components of the signal. Such comb filters incorporating video delays of television lines, fields or frames usually fail to provide adequate separation of the luminance and chrominance components of the signal where the colour information changes from one scanning line to the next or from one field to the next, ie where the picture contains vertical colour detail or motion, or contains scene changes.
Another aspect of decoders incorporating comb filters is that the inclusion of delay lines within the comb filter usually means that the output decoded picture signals are significantly delayed with respect to the input signal. Such delays are very inconvenient in decoders used in the professional studio environment where signals are usually co-timed to enable such operations as video mixing and keying to be performed. Video delays in excess of one field may also cause problems with sound synchronisation.
The present invention provides a high degree of separation of the luminance and chrominance components of the input signal, yet introduces minimal delay in its processing. It is applicable to any device requiring the luminance and colour difference components of a television signal to be separated and can operate with any form of NTSC or PAL encoded signal.


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