Xref: utzoo comp.graphics:10176 comp.sys.ibm.pc.programmer:198
Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!samsung!brutus.cs.uiuc.edu!jarthur!jseidman
From: jseidman@jarthur.Claremont.EDU (James Seidman)
Newsgroups: comp.graphics,comp.sys.ibm.pc.programmer
Subject: Re: 256 GrayScale Matching to 256 Colors
Keywords: Look Up Table Needed
Message-ID: <4767@jarthur.Claremont.EDU>
Date: 2 Mar 90 05:34:14 GMT
References: <858@dukempd.phy.duke.edu>
Followup-To: comp.graphics
Organization: Harvey Mudd College, Claremont, CA 91711
Lines: 23

In article <858@dukempd.phy.duke.edu> fang@dukempd.phy.duke.edu (Fang Zhong) writes:
>	I have some 640x480x8bit gray scale images.  I want to analyze them on
>PC with 640x480x256 color capability.
>	Can someone tell me if there exists a look up table somewhere? Or even
>there has been an existing program?
>	Thanks in advance.

You don't say what kind of video card you have, but I'm going to assume that
it's either a SuperVGA or an 8514/A.  In either case you're out of luck,
because both have palette selectors which only support 6 bit values for red,
green and blue levels.  Therefore you can only get 64 shades of gray.  You
could use "false color," i.e. make a variety of hues to represent the
different gray scales.  How well this works depends on what your pictures
are.

By a "look up" table do you mean a palette?  You can make one of these
really easily with a quickly hacked program.  I won't post details because
the format depends on what graphics card you are in fact using.
-- 
-------------------------------------------------------------------------------
Jim Seidman, Harvey Mudd College, Claremont, CA 91711.  (714) 621-8000 x2026
DISCLAIMER: I don't even know if these are opinions, let alone those of
            anyone other than me.