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From: Bob Friesenhahn <bfriesen@simple.dallas.tx.us>
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To: "Gil, Debora, VF-ES (dgilalv) STU" <debora.gil@vodafone.com>
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Subject: Re: [Tiff] FFT on two TIFF images
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On Tue, 9 Feb 2010, Gil, Debora, VF-ES (dgilalv) STU wrote:
>
> This is what made me thing about using the correlation to measure the
> resemblance. Doing the FFT with FFTW looked quite simple, but my lack of
> experience dealing with images is the main obstacle. I started reading
> about TIFF and tiles, scanlines, grayscale, rgba... but I didn't really
> understand many of the concepts... and still don't.

As John Cupitt points out, there are much easier ways to compare two 
images (assuming that pixel row/columns line up) than advanced 
programming with a FFT.  The free software I maintain (GraphicsMagick) 
also provides ready-made algorithms for comparing images.  I didn't 
mention it because it is not optimized for FAX images (but usually 
works fine).  Common comparison metrics are MAE, MSE, PAE, PSNR, and 
RMSE, as well as annotated difference images.

Bob
--
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
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