Hi,
I am after some clarification to do with the background color that gets
set in a gif animation and what happens when it changes because a
decoder that I am working on seems to handle it differently to how
other web browsers handle it.
The image I am looking at has a background color index set to 25, and
then the first image in the animation has transparency on and the
transparent color index of 25 as well, hence the background is
transparent. The image is called moving_hole_lzw_gifsicle.gif and can
be found on:
http://www.cit.gu.edu.au/~anthony/graphics/imagick6/anim_basics/
In the next frame of the animation background disposal is used but in
the graphic control extension the transparency has been turned off. Now
because of this my decoder shows the part of the image that is to be
replaced with a solid color.
So the question is whether the decoder should remember the first color
that the background is set to and save this for all future frames or
can the background color change if the palette changes for subsequent
frames? It seems that many implementations remember what the background
color is set to for the first frame and apply this throughout but I
don't think this is entirly right and the gif speciation seems a little
unclear.
Thanks,
Tom
