Why is it that on some TVs, when I'm watching something in black and white, color blotches will randomly appear. For example, if someone has a checkered shirt on, sometimes there will be a haloed prism of color on and around the shirt. This also happens during the closing credits of a movie (black background, white text). What is this and what causes it? I've noticed it since I was a kid. It annoys me so much that when I watch something in black and white, I turn the color all the way down on my TV.
It's most likely an artifact of composite video. In order to make TVs compatible when they moved from black and white to color, the broadcast signal contained a "luminance" (or Y) component that contained the B&W content and two "chrominance" (or C) components. The signals are converted into RGB values for your CRT. With standard broadcast or other composite video sources, your TV has to apply filtering to separate the Y and C video components out of the continuous signal. Noise in the source and/or inadequate filtering can result in color artifacts like you described. You should never see such artifacts if you are watching a component video source (such as DVD) with either an S-Video or component video connection to your TV. If you do, it usually means that either the source used for mastering the disc was a composite master or that the player or DVD is doing an undesirable component to composite to component conversion at some point in the chain. TVs with "3-line comb filters" are supposed to be better at separating the Y and C components than standard TVs. TVs with "3-D comb filters" are supposed to be better still. Regards,
Also, NTSC doesn't handle close checkered patterns very well. Watch some episodes of Bob Newhart. I think Johnny Carson did a skit with a fine-lined new coat on to make fun of the video results.... Todd
The MGM DVD of Billy Wilder's "The Fortune Cookie" (a black and white film)has some particularly gruesome examples of this. Keith Jackson plays a football announcer (not a big stretch) who wear's a hat with a plaid pattern. It just pulses with flickering aliasing noise (but no color). Regards,
Yes, I watched the DVD the other week and saw that too. A lot of transfers still suffer from this problem.... Todd
