This is also equivalent and may make more sense to use -channel a rather than -channel o.
transparency=`convert yourimage -resize 1x1 -alpha on -channel a -format "%[fx:u.a]" info:` examples: convert -size 100x100 xc:black -resize 1x1 -alpha on -channel a -format "%[fx:u.a]" info: 1 convert -size 100x100 xc:none -resize 1x1 -alpha on -channel a -format "%[fx:u.a]" info: 0 convert -size 100x100 gradient: -alpha copy -resize 1x1 -alpha on -channel a -format "%[fx:u.a]" info: 0.499992 _______________________________________________ Magick-users mailing list [email protected] http://studio.imagemagick.org/mailman/listinfo/magick-users
