[Magick-bugs] Image Comparing (via "compare" or "convert") returns different results on ImageMagick 6.3.0 and 6.3.3

[Keith Bernstein]

If I run this command on ImageMagick 6.3.0:

                compare -metric MAE 00029501_001_aa_x_s.jpg  00150288_001_aa_x_s.jpg null:

I get this result:

                31.5874

Likewise, if I run this command:

                convert test.jpg test2.jpg -compose difference -composite -colorspace gray -verbose info: | grep Mean

I get this result:

                Mean: 31.38 (0.123059)

 

Those numbers are much lower than the "Comparison Statistics" section of this ImageMagick Examples page:

http://www.imagemagick.org/Usage/compare/

 

If, however, I run these same commands on my co-worker's ImageMagick 6.3.3 installation, I get results like:

                compare -metric MAE 00029501_001_aa_x_s.jpg  00150288_001_aa_x_s.jpg null:

I get this result:

                8117.97

Likewise, if I run this command:

                convert test.jpg test2.jpg -compose difference -composite -colorspace gray -verbose info: | grep Mean

I get this result:

                Mean: 8064.05 (0.12305)

 

Is there an explanation for this? Can I just take (e.g.) (8117.97 / 31.5874) and use that to normalize threshold values between
these two systems?

 

Thanks for any help.

 

- Keith