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Re: Alpha blending with object graphics - different color palettes do not work [message #75782 is a reply to message #75780]

Wed, 04 May 2011 09:33

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Karl writes:

> As far as being in indexed mode goes, I don't think that the
> DECOMPOSED setting affects the way IDLgrWindows are created. (not
> sure). But you don't need to have an Indexed destination to use
> palettes in images.

Right. Nor do you want to use indexed color if you work
with Coyote Graphics image commands, although these commands
are a little more tolerant of conservative scientists
who learned to program in the 1970s and will let you
get away with it. Internally, though, the Coyote Graphics
commands *always* work in decomposed color if it is at
all possible. (It's not always possible, except on versions
of IDL starting in IDL 7.1 and higher.)

This is more or less the reason cgImage can display
images with alpha channels and with image transparency.

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: Alpha blending with object graphics - different color palettes do not work By: djh on Wed, 04 May 2011 09:43
		Re: Alpha blending with object graphics - different color palettes do not work By: David Fanning on Wed, 04 May 2011 09:33
		Re: Alpha blending with object graphics - different color palettes do not work By: Karl[1] on Wed, 04 May 2011 09:17
		Re: Alpha blending with object graphics - different color palettes do not work By: David Fanning on Wed, 04 May 2011 05:30
		Re: Alpha blending with object graphics - different color palettes do not work By: LNpellen on Wed, 04 May 2011 22:50

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