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Re: COLOR_QUAN question [message #16776 is a reply to message #16763]

Thu, 19 August 1999 00:00

Struan Gray
Messages: 178
Registered: December 1995

Senior Member

David Fanning, davidf@dfanning.com writes:

> There is no requirement, I don't think, that the
> same value be assigned the same color in two different
> instances. Only that the pixel values and the colors
> fairly represent the colors in the 3D image.

A while back someone asked for a way to force COLOR_QUAN to use a
particular color table. I tried seeding it with a dummy image
containing 256 pixels and a simple ramp through the desired table,
hoping to use /MAP_ALL and /GET_TRANSLATION to force subsequent calls
to use the same colour map.

I gave up because the colour map returned by the first call was
always different from that used to generate the dummy image. That is,
even if you feed COLOR_QUAN an RGB image with only 256 pixels (which
it should be able to reproduce exactly with an 8-bit colour table) the
RGB values of the colour map it generates are different from the
pixels' RGB values.

Struan

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[Message index]

		Re: COLOR_QUAN question By: steinhh on Thu, 19 August 1999 00:00
		Re: COLOR_QUAN question By: Liam Gumley on Thu, 19 August 1999 00:00
		Re: COLOR_QUAN question By: Struan Gray on Thu, 19 August 1999 00:00
		Re: COLOR_QUAN question By: Daniel Peduzzi on Thu, 19 August 1999 00:00
		Re: COLOR_QUAN question By: davidf on Thu, 19 August 1999 00:00
		Re: COLOR_QUAN question By: davidf on Thu, 19 August 1999 00:00
		Re: COLOR_QUAN question By: Struan Gray on Thu, 19 August 1999 00:00
		Re: COLOR_QUAN question By: davidf on Thu, 19 August 1999 00:00
		Re: COLOR_QUAN question By: Struan Gray on Thu, 19 August 1999 00:00
		Re: COLOR_QUAN question By: davidf on Wed, 18 August 1999 00:00

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