Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!samsung!uakari.primate.wisc.edu!caen!news.cs.indiana.edu!arizona.edu!ece.arizona.edu!dan From: dan@ece.arizona.edu (Dan Filiberti) Newsgroups: comp.sys.next Subject: Re: ColorStation questions Message-ID: <1991Apr25.221947@ece.arizona.edu> Date: 26 Apr 91 05:19:47 GMT References: <1991Apr24.082948.17763@cs.ucla.edu> <559@rosie.NeXT.COM> <1991Apr24.231003@ece.arizona.edu> <1991Apr25.180420.9712@menudo.uh.edu> Reply-To: dan@ece.arizona.edu (Dan Filiberti) Distribution: usa,local Organization: University of Arizona Dept. of Electrical and Computer Engineering Lines: 71 Nntp-Posting-Host: dialsun.ece.arizona.edu Alright, this is to all the smartass comments I've been getting. Almost all the news in this newsgroup that I've been reading claimed that the ColorStation has 4096 color "palette" and 16 some odd million colors to choose (that's 8bits, rgb, for you illiterates who have responded to my previous posting). This implies that the palette can be modified. My posting was in repsonse to the statement that there are 3 LUTs, rgb, each adressed by 4 bits and returning an 8bit value. I assumed that the 8bit value was modifiable. Thus, you can choose 16 colors ( thats one per 4bit address, rgb), and the rest are permutations of those 16...ok, understand what I was saying now? Sorry if my typo (six instead of sixteen) confused you that much. This allows for only 16 shades of grey, red, green or blue. Now, people are posting that the Colorstation has a static CLUT of 4096 colors... that means that 4bits rgb divide the 16.7 million colorspace into 4096 colors. Which means that the statement that the ColorStation has 16.7million colors to choose is a LIE. There are only 4096 colors available, and unfortunately only 16 shades of pure red, green, blue, or grey. And, if this is true, then why do they even need CLUTs or palletes? It completely defeats there purpose. As to why this is a problem, here it is. Our research involves determining whether diagnosis of images by dermatologists is affected by things such as color quantization, image coding, compression, etc... Unfortunately, you can't determine this by showing dermatologists dithered pictures all of the time. You must show them "ideal" images, 24bit truecolor. So, the Next ColorStation is useless for this purpose, except for showing the dithered and quantized images. And, as you can see, with only 16 pure shades of red available, this may not work either, (since skin is predominately red). As for upgrading to the NeXTDimension board, that would be fine, for 24bit color. But, how you going to get the highest resolution images into the frame grabber without RGB input? S-Video and NTSC are degraded signals, and once again, for our research you must start with the best. There are many others who require RGB input also, especially since its the only way to get the highest quality image into the frame buffer from a camera. And there are no other feasible hardware solutions that I have heard about for the NeXT Cube. No, I don't need to consult a Raster Graphics Manual. I work with image processing every day, and completely understand the concept of a frame buffer, CLUT, and palletes. So, eat all your dumb comments, and instead post the truth about the hardware, and suggest some solutions to the problem... For all who replied politely, thanks...:) Daniel Filiberti dan@helios.ece.arizona.edu [:)} ------------- "If you want to flame, post on rec.games.mud..." -------------