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Re: overlaying a transparent 24-bit image with different pixel scale [message #73231 is a reply to message #73230]

Fri, 29 October 2010 11:36

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Jeremy Bailin writes:

> I can calculate the appropriate normalized coordinates corresponding
> to the corners of where the image should be placed. I've tried feeding
> that and the 24-bit image into TVIMAGE, but it uses a white background
> for the alpha channel, not what already exists on the display. And
> David's example for overlaying things (http://www.dfanning.com/ip_tips/
> transparentpng.html) assumes a relative pixel scale of 1.

Well, a new keyword will probably fix that up! :-)

I was going to make a change to TVImage today anyway,
so I might as well do this at the same time. My only
concern is that if I take what's in the display window
as the background for the alpha channel, this will NOT
make it possible to display the image in PostScript.
(No window to read from.) Is this a limitation you
can live with?

Cheers,

David

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

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[Message index]

		Re: overlaying a transparent 24-bit image with different pixel scale By: David Fanning on Fri, 29 October 2010 13:35
		Re: overlaying a transparent 24-bit image with different pixel scale By: Jeremy Bailin on Fri, 29 October 2010 13:13
		Re: overlaying a transparent 24-bit image with different pixel scale By: David Fanning on Fri, 29 October 2010 12:24
		Re: overlaying a transparent 24-bit image with different pixel scale By: Jeremy Bailin on Fri, 29 October 2010 11:47
		Re: overlaying a transparent 24-bit image with different pixel scale By: Jeremy Bailin on Fri, 29 October 2010 11:44
		Re: overlaying a transparent 24-bit image with different pixel scale By: David Fanning on Fri, 29 October 2010 11:41
		Re: overlaying a transparent 24-bit image with different pixel scale By: David Fanning on Fri, 29 October 2010 11:36

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