From: Axel Kohlmeyer (
Date: Wed Jun 09 2010 - 13:08:57 CDT

On Wed, 2010-06-09 at 18:18 +0200, maria goranovic wrote:
> Dear John

dear maria,

> It is not entirely clear to me what exactly will be required for the
> alternate method .. ? Are you talking about writing some lines to
> the .dat

yes, john was suggesting to help placing an alternate background
in the image.

> that is output by tachyon? Can a transparent background be saved in
> other image formats such as tga or tif?

no. there is currently no way to generate an image with a transparent
background (directly). this has nothing to do with the file format.

what i typically do to generate transparent images is to do
something similar to the "greenscreen" or "bluescreen" process
in TV and movies. you select a background color that does not
show up in your image, render, and then postprocess in gimp or
photoshop (add alpha channel, select by color, delete region).
the problem of this process is that you can get a small "halo"
in background color due to antialiasing. to some degree this
can be avoided by rendering the image at the correspondingly
large size and then doing the anti-aliasing after the background
has been converted to transparency. requires more memory and
storage, though.


> On Wed, Jun 9, 2010 at 5:06 PM, John Stone <> wrote:

Dr. Axel Kohlmeyer
Institute for Computational Molecular Science
Temple University, Philadelphia PA, USA.