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Article #609

HELP! Its Those Damned Colormaps!

#609
From: Jeff Michel
Date: Tue, 22 Dec 1992 19:57
24 lines
1759 bytes
I *hope* this is a FAQ.

I'm doing frame-by-frame animation on Sun-4's.  My approach is to
put up sequences of images converted to the Sun-specific, video-RAM specific
(pixrect) format and colormap format (pixrect) of the graphics hardware (cg6) of
the machine.  (This graphics architecture makes use of a 24-bit, 256 color
colormap.)

The problem with this approach has been that when the colormaps of two
consecutive images in the sequence differ, there is a brief instant during which
the colormap for the previous image is loaded, but the image loaded on the screen
needs a different colormap.  The result of this is an annoying *flicker*.  Are
you nodding your head?  Have you seen this problem?

What I'd like is for all of the video-RAM format images to have the *same*
colormap so that the problem of flicker never arises.  So, after three
paragraphs, my question is: "Is there any software available which will allow me
to normalize the colormaps of a sequence of Sun rasterfile images into *one*
common colormap including all or most of the colors of the images of the
sequence?"  If not for Sun, then is there source code for the normalization of
*any* colormap-oriented graphics architecture (eg. VGA)?

Thanks,
Jeff Michel	jrm2k@Virginia.EDU
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Message-ID: <1992Dec22.195753.8789@murdoch.acc.Virginia.EDU>
Path: arc1-ca.pugleaf.net!sparky!uunet!gatech!concert!uvaarpa!murdoch!uvacs.cs.Virginia.EDU!jrm2k

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Newsgroups: comp.graphics.animation
Path: arc1-ca.pugleaf.net!sparky!uunet!gatech!concert!uvaarpa!murdoch!uvacs.cs.Virginia.EDU!jrm2k
From: jrm2k@uvacs.cs.Virginia.EDU (Jeff Michel)
Subject: HELP! Its Those Damned Colormaps!
Message-ID: <1992Dec22.195753.8789@murdoch.acc.Virginia.EDU>
Keywords: sun-rasterfile, vga, colormap, normalize
Sender: usenet@murdoch.acc.Virginia.EDU
Organization: University of Virginia Computer Science Department
Date: Tue, 22 Dec 1992 19:57:53 GMT
Lines: 24