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Re: color mapping question [message #6810 is a reply to message #6806]

Thu, 29 August 1996 00:00

Christian Soeller
Messages: 46
Registered: August 1996

Member

gennari@universe.Hawaii.edu (Scott Gennari) writes:

> I have a 256 color grayscale image and i'd like to overlay a
> coastline with some color (red). How would I strech the grayscale
> data values to fit 0-254 and reserve value 255 for a certain rgb
> color? I'm Not having much luck with STRETCH,0,254 and then assigning
> a rgb color to 255.

Even on a 256 color display IDL will in general only have a subset of all
those colors as a few are normally already allocated by other applications.
The actual number of colors available to IDl can be found in the sys var
!D.TABLE_SIZE. So you might try to scale your data to 0...!D.TABLE_SIZE-2
and assign the color number !D.TABLE_SIZE-1 to red (colors 0...!D.TABLE_SIZE-2
set to shades of grey from 0 to 255). You get the idea. See also documentation
for the TVSCL procedure.

Hope this helps,

Christian

------------------------------------------------------------ --------
Christian Soeller mailto: csoelle@sghms.ac.uk
St. Georges Hospital Medical School Dept. of Pharmacology
Cranmer Terrace London SW17 0RE

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[Message index]

		color mapping question By: gennari on Thu, 29 August 1996 00:00
		Re: color mapping question By: Liam Gumley on Thu, 29 August 1996 00:00
		Re: color mapping question By: Christian Soeller on Thu, 29 August 1996 00:00
		Re: color mapping question By: David Foster on Thu, 29 August 1996 00:00

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