Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!usc!apple!sun-barr!newstop!texsun!pollux!attctc!chasm From: chasm@attctc.Dallas.TX.US (Charles Marslett) Newsgroups: comp.sys.ibm.pc Subject: Re: Super Duper VGA boards Summary: Gotta talk to the monitor Message-ID: <10414@attctc.Dallas.TX.US> Date: 30 Nov 89 14:58:35 GMT References: <8911250811.AA26716@cie.uoregon.edu> <10401@attctc.Dallas.TX.US> <4033@peora.ccur.com> Organization: The Unix(R) Connection, Dallas, Texas Lines: 38 In article <4033@peora.ccur.com>, joel@peora.ccur.com (Joel Upchurch) writes: > In article <10401@attctc.Dallas.TX.US>, chasm@attctc.Dallas.TX.US (Charles Marslett) writes: > > > The Tseng Labs ET4000 chip (going into full production early next year) > > will support 65536 colors and is a VGA chip, so it will handle all the > > standard VGA modes as well. The 16-bit/pixel modes do require some .... > > It seems to me that if a board supports 16-bits/pixel that it would be > better to have the colors map directly rather than going through a > mapping table. With 5 bits each for red, green and blue that would > give you 32k colors to work with one bit left over. This would eliminate > the overhead of setting up the color mapping table as well the > hardware to do the mapping. The problem here is that the mapping I was talking about was going from 16-bit binary (digital) information in the video card's RAM to a 3-wire analog signal at the monitor. The DAC, that is. A problem with eliminating random mapping comes up when you want to do gray scaling (check recent messages in the comp.sys.atari.st group) -- with a fixed 5-bits/color map you only get 32 gray shades, even with 16 bits per pixel. > Does anyone know how many different colors a normal monitor can display > that the human eye can actually tell apart? It depends a whole lot on the patterns (a smooth gray ball requires perhaps 100 -- I see lines with 64), whether there are really boundaries in the image or not. The human eye is very good at extracting structure from a field of view, and sometimes we don't want it to (as in smooth shading). > -- > Joel Upchurch/Concurrent Computer Corp/2486 Sand Lake Rd/Orlando, FL 32809 > joel@peora.ccur.com {uiucuxc,hoptoad,petsd,ucf-cs}!peora!joel > Telephone: (407) 850-1040 Fax: (407) 857-0713 Charles Marslett chasm@attctc.dallas.tx.us [VGA BIOSes, DOS drivers, X servers, what comes next!]