Attached is a patch for swfextract.c allowing you to extract the alpha mask from DefineBitsJPEG3 tags. It is against the latest 2009-08-24-2042 source.
When extracting a JPEG with "-j", the new "-a" option can be used to specify the file to save the alpha channel into (if found). The file is output as a 8bpp greyscale PNG. This can then easily be combined with the JPEG as required, for example using ImageMagick: $ ./swfextract source.swf -j 6 -o extracted-image.jpg -a extracted-alpha.png $ convert extracted-image.jpg extracted-alpha.png -compose copy_opacity -composite out.png Example output: http://www.davidc.net/~david/pics/swftools/ Please accept this patch for the next version of swftools. Regards, David Croft
swftools-swfextract-alpha.patch
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