Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!ccu.umanitoba.ca!herald.usask.ca!telepro!tptbbs!James_Hastings-Trew From: James_Hastings-Trew@tptbbs.UUCP (James Hastings-Trew) Newsgroups: comp.sys.amiga.multimedia Subject: Re: DCTV digitized frames Message-ID: Date: 15 Jun 91 04:30:03 GMT Organization: TelePro Technologies Lines: 37 In a message dated Thu 13 Jun 91 09:07, Kdarling@hobbes.catt.ncsu.edu (kevi wrote: K> Sidenote: I thought the DCTV makers only claim 4 million colors, which K> is K> 22 bits. And a competitor's checking seems to show that the color K> changes K> are limited per line, and only apply to every other line (altho K> luminance K> changes can occur on every line). In any case, it's definitely not K> true K> "24-bit output". Probably better to just claim the total color range K> :-) Digital Creations does not like to quote resolutions and colours, as their device outputs a composite video signal, no more, no less. The colours are NOT "pixel" addressable. For a competitor to compare DCTV to a true frame buffer or other "pixel mode" box is unfair - it is comparing apples and oranges. In practice, the luminance changes for each pixel displayed (within the limits of composite video) but the chroma changes much more slowly. At a guess I would say that the chroma is at 1/2 to 1/3 the resolution of the luminance portion of the signal. If you want to see this in action, take a black screen, and draw a RED filled circle on the screen. You should see some MAJOR stairstepping taking place at the edge of the object. Now put a GREY circle on the screen. No stairsteps. The DCTV device can get away with this because this is actually a common video situation - VHS tapes from most consumer VCRs are like this. With a normal "picture" image the effect is invisible. For computer-generated imagery, all it takes is some care in the image creation to avoid extreme situations. Taken for what it is, the DCTV unit is a great box. Don't take it for what it isn't - a 24 bit display.