Transparency in sub-image search result
Posted: 2013-02-28T21:59:16-07:00
If I do a sub-image search on a GIF image which has a transparency channel the resulting 'map' has random transparency in the result...
This downloads a GIF image, crops a 50% sub-image and feeds them to compare.
The second 'map' image (which is what we are interested in) that is generated by compare has some random transparency in it.
There should be no transparency as it is a grayscale map of 'color distances'.
The transparency in that map should not exist, and looks like undefined random memory data.
Turning off the alpha channel before the final save works, but should have been performed by the "compare" program...
ASIDE: compare, and sub-image compare should be merged into IMv7 "magick".
Code: Select all
convert http://www.imagemagick.org/Usage/images/colortable.gif \( +clone -crop 50%x+0+0 \) miff:- | compare -subimage-search - | convert - -delete 0 result.pngThe second 'map' image (which is what we are interested in) that is generated by compare has some random transparency in it.
There should be no transparency as it is a grayscale map of 'color distances'.
The transparency in that map should not exist, and looks like undefined random memory data.
Turning off the alpha channel before the final save works, but should have been performed by the "compare" program...
ASIDE: compare, and sub-image compare should be merged into IMv7 "magick".