Comments

JumboTech wrote on 10/6/2002, 10:02 PM
I assume that you mean what I call "Dot crawl"? It is a limitation of the NTSC system as far as I am aware caused by the chroma information affecting the luminance info as opposed to cross color (the sort of moire patterning on fine checks and plaids which is the other way round). You could perhaps soften the image (which I can understand that you would hate to do) or change the combinations of colors in your animation if possible since it is worse between certain color combinations. How is the anim going to be presented? Using S video for instance, reduces it while component should get rid of it completely. Also watch that your colors are not too hot for NTSC and keep the sharpness down on the final display monitor if you have to use composite video. Not very good news, I'm afraid but on the plus side, I always blame the monitor not the artist when I see dot crawl. You can even see it from a Tektronix NTSC generator if the monitor permits.

Al
edna6284 wrote on 10/7/2002, 10:11 AM
Thanks JumboTech, I appreciate your feedback. It's very helpful, although I hope I don't have to change anything at this stage! DE
riredale wrote on 10/7/2002, 11:33 AM
JumboTech is correct. Actually, dot-crawl is an artifact created by the use of a simple NTSC codec model. A more sophisticated version keeps the luminance and chrominance information completely separated, and dot crawl is eliminated. Alas, the folks in charge at the FCC don't care, which is why back in 1990 they decided to throw out the NTSC system and start from scratch with the new DTV model. As the past 5 years have demonstrated, this will be a much more difficult transition than they envisioned.

There are lots of ways to greatly improve the NTSC system. We were proponents back in 1988 of introducing an HDTV version of it (called HD-NTSC) which was completely forwards- and backwards-compatible with current NTSC. For several reasons the feds said no. To me, at least, it's a fascinating story, but the "bottom line," as usual, was money--namely, money in the form of broadcast spectrum. Someone should write a book.
HPV wrote on 10/7/2002, 2:19 PM
You're going to have to rerender to drop the color saturation via the HSL filter or use an external tbc with proc. amp section. The broadcast colors filter doesn't do it, that just adjust the luma range. Contrast adjustments can help also.
Craig H.