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From: bpendlet@es.com (Bob Pendleton)
Newsgroups: comp.windows.x
Subject: Re: COLOR image sequences under X
Keywords: colormap, moving images
Message-ID: <1991Feb26.230843.26036@dsd.es.com>
Date: 26 Feb 91 23:08:43 GMT
References: <11371@pasteur.Berkeley.EDU>
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Reply-To: bpendlet@dsd.es.com
Organization: Evans & Sutherland Design Systems
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In article <11371@pasteur.Berkeley.EDU>, gilge@ICSI.Berkeley.EDU (Michael Gilge) writes:
|> 
|> Has anybody experience with dynamically changing colormaps or color animation
|> on 8-bit displays? I tried all tricks I know of, e.g. XFlush, XSync. I can 
|> stop the animation at any time and all colors are right. The effect is strictly dynamic and changes when I vary the frame rates. I have a feeling that there
|> is some kind of conflict between the screen refresh and the X-server update
|> of the colormap.

I would guess that the color map is only being loaded during vertical
retrace. This would cause a considerable pause, 1/60 of a second,
every time you change the color table. This might cause the effect you
are seeing.

|> Your suggestions are greatly appreciated.......

Instead of reloading the color table for each image try coming up with
an 8 bit true color color table and load it only once. A good approach
is to allocate 3 bits for red, 3 bits for green, and 2 bits for blue
in each of your 8 bit pixels. If the color table is set up correctly
you will get the effect of a true color display.

I'd hope that this would get rid of your flashing problem and speed up
your conversion from 24 bit RGB to your displayed images.



-- 
              Bob Pendleton, speaking only for myself.
   bpendlet@dsd.es.com or decwrl!esunix!bpendlet or utah-cs!esunix!bpendlet

                         Tools, not rules.