White dots become coloured on TV

philfort wrote on 10/16/2002, 10:22 PM

I've got a project that contains some "white dots", both in the form of a star field, and dots connecting names in a credit roll. When I print to tape (DV) and watch it on a TV, what were white dots (on a black background) are now coloured. It gets much worse when the dots are moving... what is supposed to be a smoothly scrolling star field turns into a field of dots constantly changing colour. Likewise, the dots in the credit roll shimmy up and down a little (and change colour) as they scroll. Very distracting.

I've recaptured the movie from DV back into the computer, and I don't see this effect on my computer screen in the recaptured video. All the dots are white again.

I am using the NTSC DV (720x480, 29.970) template, lower field first.

Is it just because I have a crappy TV? It's small (12 inches), so maybe a white dot resolves to just part of one RGB pixel? Has anyone seen this before?

Comments

John_Cline wrote on 10/16/2002, 11:22 PM

Yeah, it's the TV. Your dots are probably too small. Plus, they are white, which means that the red, blue and green guns in the TV are all pretty much full on simultaneously. This is a worst case situation for a TV whose convergence adjustments are out of whack.

John

SonyDennis wrote on 10/18/2002, 10:56 PM

All that, and if you're using a composite (or worse, RF) connection instead of s-video or component, you're going to get crawling colors, which on white dots would probably be a flicking effect.

Try applying a little Gaussion Blur to the star field. This will reduce the high spacial frequencies and reduce chroma artifacts.

///d@