Re: [MacPerl] comparing image files

[jean-michel meyer <mjm@aix.pacwan.net>]

>I'm interested in comparing image files, in order to find duplicates.
>Because there are several thousand files, an NxN comparison is out of
>the question.  Also, it is quite possible that some of the images may
>have been resized or tweaked in other manners, so the comparison will
>not be an exact one.  Finally, the images are mostly in JPEG format,
>so they will have to be expanded into pixels before any comparison
>can be done.
>

Hello,

I did work on such a problem when i was student (working on landscape's
elements cognition in the geographic dept.)

One way we did work was to  use a simple statistical comparision, sometime
on one random part, sometime on the whole image, of any image file pairs,
with a simple correlation on one composent of the image. If the image file
are CMYB, the black composent is enought to made a correlation check.

Anyway you 'll have to human check the quality of the result, but it did
work very well on similary sized (in pixels) image files.

The code is probably lost but it wasprobably  not so difficult because we
did it ;-)

Hope it help.
MJM




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