Is there such thing as a 'soft checksum' tool?

[parv at pair.com]

in message <44skf0c6zq.fsf at lowell-desk.lan>,
wrote Lowell Gilbert thusly...
>
> Modulok <modulok at gmail.com> writes:

(I am replyin to Lowell's reply for I do not have OP.)


> > I'm not even sure such a tool exists, but it's worth asking:
> >
> > I'm looking for a pseudo-checksum tool for use with catalogging
> > images. For example, a strict checksum algorithm, like the sha
> > family, will produce a dramatically different checksum for two
> > files which differ by only a single bit. I'm looking for
> > something where two images images, which are similar, get a
> > proportionally similar checksum. When I speak of similarities
> > I'm referring to their image patterns. i.e two images of
> > differing sizes, which are otherwise identical, would produce
> > very similar checksums. So the closer the checksums are, the
> > more similar two given images are.
> >
> > Does anyone know of anything like this?

See if this ...

  http://www.stonehenge.com/merlyn/LinuxMag/col50.html


... fits.


  - parv

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