"Marcel Wouterse" on wrote...
| What i am actually trying to do is add transparency to an animated gif:
|
| This is the original:
| http://www.online-image-editor.nl/examples/trans_original.gif
| (has a white background)
|
| This is my result after I make white the transparent color:
| http://www.online-image-editor.nl/examples/trans_bad.gif
|
| And this is how it should be, but I don't know how to get this with IM:
| http://www.online-image-editor.nl/examples/trans_good.gif
|
| Anybody know the difference between the "bad" and the "good" version?
|
The problem, is two fold.
1/ Because your GIF image now contains transparency, the GIF dispose
methods will need to be modified to correctly handle the clearing
of the transparency.
The simplist way would be to -coalesce your image first, then use a
-fill none -draw 'color 0,0 floodfill'
options to clear the area areound the transparency.
Now if you have the latest IM version you can now use
-layers Optimize
to optimize your animation and set the appropriate dispose method
so the animation works as defined by its coalesced form.
For full details see
http://www.cit.gu.edu.au/~anthony/graphics/imagick6/anim_basics/
2/ The other problem is the shadow outline, and other white edges.
This is because the animation was overlayed onto a white background
before shrinking to allow the image to be correctly anti-aliased.
Unfortunatally while GIF can anti-alias an edge to a color, it can
not do so to a transparency as transparency is purely an on/off
relationship in the format.
Solutions for this is basically to try and overlay the original
transparent image onto a color simular to the background color of
the page you are planing to use it on.
This becomes a particular problem when deailing with shadows which
were generally originally created using a semi-transparent black.
See
http://www.cit.gu.edu.au/~anthony/graphics/imagick6/formats/#trans
for more information and techniques.
Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]>
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Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/
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