How to compare 2 images from command line

FreeBSD freebsd at
Tue Sep 2 15:24:35 UTC 2008

Tom Marchand a écrit :
> Hash the images and compare the hashes.
>  -------------- Original message ----------------------
> From: FreeBSD <freebsd at>
>> Hi everyone,
>> I'm trying to determine if 2 jpeg images are identical. The images are 
>> screenshots taken with scrot at different times. The point is to know if 
>> the display is working correctly. I tried to use 'diff' but without 
>> success, probably because of the metadata included in the image. I also 
>> tried the 'compare' command from imagemagick, but it produce an image 
>> containing the difference between the 2 images instead of telling me if 
>> both images are identical.
>> So, my question is what are you using to determine if 2 images are 
>> identical?
>> I'm using FreeBSD 7.0 and I need to be able to script this comparaison 
>> for an integration in Nagios.
>> Thank you,
>> Martin

I just tried it and it doesn't work. The hashes are different. I can't
say that I'm surprised since 'diff' is "seeing" a difference between the
two identical images.

Thanks for the suggestion

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