Compare 2 images

[imagetester]

Well I'd like to compare two images:
I 'd like to reach a point where i can say that the first image matches the second one at nearly NUMBER%.

Eventually the comparison criteria is the shape, but colors can also be be added on.
Is it too difficult? Is there any function that can achieve this task?!!

[magick]

To compare two images, use the compare utility. See http://www.imagemagick.org/script/compare.php.

[anthony]

for more information and actual technqiues see IM Examples, Comparing Images
http://imagemagick.org/Usage/compare/