Guy Rutenberg » ImageMagick http://www.guyrutenberg.com Keeping track of what I do Sat, 21 Aug 2010 11:44:14 +0000 en hourly 1 http://wordpress.org/?v=3.0.1 Alpha Channel Problems When Creating .ico Files Using ImageMagick http://www.guyrutenberg.com/2008/10/05/alpha-channel-problems-when-creating-ico-files-using-imagemagick/ http://www.guyrutenberg.com/2008/10/05/alpha-channel-problems-when-creating-ico-files-using-imagemagick/#comments Sun, 05 Oct 2008 15:30:42 +0000 Guy http://www.guyrutenberg.com/?p=102 I’ve tried to use ImageMagick to create .ico files for Open Yahtzee, out of PNGs of various sizes. The command as it should have been:

convert openyahtzee16.png openyahtzee32.png openyahtzee64.png openyahtzee.ico

resulted in the alpha channel being reversed. I’ve used ImageMagick 6.4.0, and I didn’t remember this misbehavior happening in the previous versions.

While this annoyed, and was due to no apparent reason, it could be easily solved using the ImageMagick switches to reverse the alpha channel:

-channel Alpha -negate

So the command that produces a correct .ico file was:

convert openyahtzee16.png openyahtzee32.png openyahtzee64.png -channel Alpha -negate openyahtzee.ico
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