[magick-users] Problem resizing animated gif

[Anthony Thyssen]

"Marcel Wouterse" on  wrote...
| Hi IM Team,
| 
| I have installed Version 6.2.9 yesterday (I was still on 6.2.6).
| 
| Now I have a problem with rezising animated gifs with transparency in
| it.
| 
| If I take the following picture:
| http://www.online-image-editor.net/examples/imagemagick/kitty.gif
| 
| And resize it with the command:
| convert kitty.gif -coalesce -resize 50x40! Out.gif
| 
| I get the following result:
| http://www.online-image-editor.net/examples/imagemagick/out.gif
| 
| (Transparency is gone and turned black)
| I have also seen that transparency sometimes turns to gray.
| 

I can verify that this is also the case in the latest Beta version of IM
too.

This should not have happened, but I am also not suprised either...
At this time a lot of work is being done with color quantization,
especially transparency, and GIF handling.  That would be the cause of
the loss of transparency.

Basically color quantization (picking a reduced number of colors for an
image) may need some twinking to allow boolean transparency to be
handled correctly.

For example see my transparency quantization
   http://www.cit.gu.edu.au/~anthony/graphics/imagick6/quantize/#color_trans

Leave the images online, and we will look at the problem further
once the current bug problem round is finished.

At that time I should be able to get back to the GIF animation resize
examples area.
   http://www.cit.gu.edu.au/~anthony/graphics/imagick6/animations/#resize


  Anthony Thyssen ( System Programmer )    <A.Thyssen at griffith.edu.au>
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     Anthony's Home is his Castle     http://www.cit.gu.edu.au/~anthony/