For analog color television standards such as PAL and NTSC, the requirement of backward compatibility to existing black-and-white televisions dictates that the transmission of color has to take place within the band available for the gray-scales. For that purpose, the color component (C) is modulated onto a subcarrier and added to the gray-scale component (Y), and the resulting composite color video signal is used for transmission.
At the television receiver, the required separation of Y and C can only be imperfect as both components now share the same frequency space. Modern televisions apply so-called comb-filters that exploit the opposite chrominance phase of adjacent samples to separate both components. However, cross-talk artifacts and loss of resolution continue to appear in situations where few samples meet the strict requirements of the used comb-filter kernel.
In this report, a novel comb-filter kernel
is proposed that uses samples with non-opposite chrominance phases for
Y/C separation. To exploit these additional decoding options, a comb-filter
is proposed that locally selects the comb-filter kernel that yields superior
results. Subjective and objective evaluations have shown that the proposed
comb-filter achieves a significant increase in luminance resolution and
reduction of cross-talk artifacts when compared to current high-end comb-filters.