Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!helios!bcm!dimacs.rutgers.edu!rutgers!cbmvax!raible From: raible@cbmvax.commodore.com (Bob Raible - LSI Design) Newsgroups: comp.sys.amiga.graphics Subject: Re: Colorburst and Animation Message-ID: <19919@cbmvax.commodore.com> Date: 15 Mar 91 22:44:55 GMT References: <13948@life.ai.mit.edu> <1991Mar15.193235.2926@cs.mcgill.ca> Reply-To: raible@cbmvax.commodore.com (Bob Raible - LSI Design) Organization: Commodore, West Chester, PA Lines: 31 In article <1991Mar15.193235.2926@cs.mcgill.ca> tinyguy@cs.mcgill.ca (Yeo-Hoon BAE) writes: > >One thing I always wondered about 24bit cards: > > Is it really necessary to use all 24 bits? > From quick calculation, 18 bits are more than enough to > display 640x400 screen with every pixel having different > colors. So why not have 24 bit palettes and use 18 bits > or less for the lower resolutions? This should give some > improvements to the overall animation performance... > > Unless I misunderstand your question, I believe you are confusing palette depth and width. 24 bits refers to the width of the palette output, in this case 8 bits of red,green, and blue. This means that over 16 million colors are displayable, and you are correct in stating that this greatly exceeds the 307,200 pixel positions on a 640 by 480 screen. However this is pretty much irrelevant since often what we desire to do is display 307,200 pixels in colors thta are indistinguishable from the colors of the original image. In this case there are two separate issues. First do we have sufficient DEPTH in the palette to display the image? Obviously in the case of VGA display systems 256 colors is spreading things pretty thin(256 vs 307200). The second issue is whether we have sufficient color resolution(palette width) to accurately display an individual pixel. Often in the case of flesh tones or solid modeling we have pixels in adjacent screen positions that are only slightly differeentiated. In this case palette width is extremely important and 24 bits might not be enough. I hope this has helped explain the roles of palette width and depth, and why 24bits really has no connection to display size.