Date: Sat, 5 Sep 2009 21:21:07 -0400 (EDT) From: vogelke+unix@pobox.com (Karl Vogel) To: freebsd-questions@freebsd.org Subject: Re: Is there such thing as a 'soft checksum' tool? Message-ID: <20090906012107.E2731B7DD@kev.msw.wpafb.af.mil> In-Reply-To: <64c038660909050933h25a91edcw56688993f5557ad2@mail.gmail.com> (message from Modulok on Sat, 5 Sep 2009 10:33:03 -0600)
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>> On Sat, 5 Sep 2009 10:33:03 -0600,
>> Modulok <modulok@gmail.com> said:
M> I'm looking for a pseudo-checksum tool for use with cataloging images.
M> For example, a strict checksum algorithm, like the sha family, will
M> produce a dramatically different checksum for two files which differ by
M> only a single bit. I'm looking for something where two images, which
M> are similar, get a proportionally similar checksum.
This works pretty well with text, but I don't know about images.
http://ixazon.dynip.com/~cmeclax/nilsimsa.html
What's a nilsimsa code?
A nilsimsa code is something like a hash, but unlike hashes, a small
change in the message results in a small change in the nilsimsa code.
Such a function is called a locality-sensitive hash.
--
Karl Vogel I don't speak for the USAF or my company
Garlic gum is not funny. --written on blackboard by Bart Simpson
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