Re: transparent GIF pixels

[Craig Markwardt <craigmnet(at)cow.physics.wisc.edu>]

davidf@dfanning.com (David Fanning) writes:

> Kenneth Mankoff (mankoff@lasp.colorado.edu) writes:
> 
> > Is it possible to create transparent pixels? 
> > 
> > It appears from the help that you can, but only when you write png's to
> > disk. I have tried this and have been unsuccessful.
> > 
> > Anyways, i want to do it in a situation where i don't write and immediatly
> > read just to get my transparencies. I would like to make them transparent
> > while the image is in memory. And i would prefer gifs, not png's.
> > 
> > thanks for any clues or pointers.
> 
> I'd try something like this with a 2D image:
> 
... deletia ...

David, I think he's talking specifically about GIF transparent pixels.
I understand that you can reserve one GIF color to be transparent, so
to speak.  Any pixels with that color are not rendered, so any
background graphics can show through.  This can be especially useful
in web programming.  I don't think he's actually trying to render it
on the screen himself.

Unfortunately, the answer to the question appears to be that there is
no way to assign transparent GIF pixels in IDL.  There are no options
to WRITE_GIF that would satisfy this requirement.

Craig


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Craig B. Markwardt, Ph.D.         EMAIL:    craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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