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Transparency in object_graphics [message #64704]

Tue, 13 January 2009 09:35

dcleon@gmail.com
Messages: 12
Registered: November 2007

Junior Member

All,
Hopefully I'm missing something obvious. IDL's help pages indicate
that its possible to get a 4-channel image using the IMAGE_DATA
keyword to IDLgrWindow:GetProperty and IDLgrBuffer::GetProperty
methods. Yet, whenever I try I end up with a 3-channel (RGB) image
despite the fact that I'm successfully using transparency in the
images I'm producing.

Does anyone know if its possible to get 4-channel output through the
IMAGE_DATA property ? What causes transparency to be disabled in
IDLgrWindow or IDLgrBuffer when it was being used in the graphics tree
being drawn ?

My goal is to output plots with transparent backgrounds using
WRITE_PNG (I'm aware that this will require conversion to an indexed
color model). Since the background color gets blended with the some
of the graphics elements it doesn't work to simply include the
background color in the TRANSPARENT array on the call to WRITE_PNG.

Thanks.
dave

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[Message index]

		Transparency in object_graphics By: dcleon@gmail.com on Tue, 13 January 2009 09:35
		Re: Transparency in object_graphics By: Karl[1] on Wed, 14 January 2009 14:40

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