When we had this thread starting on 2004/5/18, I suggested to make
"transparent" regions white and then to use "convert -transparent white".
Roy suggested to use Gimp's "color to alpha" filter. Indeed, this filter
gives much better results, but it was a pain to use interactively.
Now I wrote this little script ("trans-white") to let gimp cut out
white parts non-interactively. Of course, other colors ccould be used,
too (e.g. ugly pink). Parts that should remain white and non-transparent
can still be colorized 254/254/254 (-> white enough :-).
if [ $# != 2 ]; then
echo "USAGE: `basename $0` <infile> <outfile>"
cat <<-EOF |gimp -i -c -d -f -b -
(img (car (gimp-file-load 1 "$INFILE" "$INFILE")))
(drawable (car (gimp-image-active-drawable img)))
(plug-in-colortoalpha 1 img drawable '(255 255 255))
(gimp-file-save 1 img drawable "$OUTFILE" "$OUTFILE")
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