🚀 go-pugleaf

In article <ck.713491034@iconix.oz.au> ck@iconix.oz.au (Chris Karadaglis) writes:

> Ok. Understood. But exactly what does it contain? I just can't seem to
> grasp what the phase information in a 2d FFT actually means. I'm after
> an intuitive answer, not a mathematical one. With 1d signals, it's a
> little bit easier.

I don't understand your confusion.  The meaning of phase in a 2-D
image is _precisely_ the same as that of phase in a 1-D signal: each
pixel (sample) in the image (signal) has a modulus component and a
phase component.  Think of it in a vector way: the modulus is the
length of an arrow with its blunt end at the origin, and the phase
gives the direction in which the arrowhead points.

This is why it's important not to fiddle with the phase when filtering
(which fiddles with the amplitude).  There are demonstrations of the
relative importance published, such as mixing the phase of one image's
FT with the amplitude of another image's FT and then inverting the
transform: the `phase image' is usually dominant.

--
 Dr Adrian F. Clark                                   JANET: alien@uk.ac.essex
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 Dept ESE, University of Essex, Wivenhoe Park, Colchester, Essex, C04 3SQ, UK.