Sharpness

[wa2ise]

Old color TV sets used a "notch filter" to separate the chroma subcarrier from the luma (black and white) video. In the 80s sets started to use comb filters to do that, and allowed more resolution from the luma thru. But you'd see crawling dots on color transitions, and you'd see large regions of crawling checkerboard patterns on colored areas if the set had no filtering. The notch filter would remove pretty much everything in the luma above 3 MHz, and that's the missing sharpness. I used to work for RCA doing better chroma luma separators in the 80s.