Dear R-users,

 

I have seen many times posts about Fourier transform, and I
am trying to do one right now. Before to apply any scripts, I wonder whether it
could properly apply to my problem, and even though it’s not a
statistics-helpers mailing list maybe one of you would be able to answer my
question without struggling to much (like I’m doing now…). 

 

I would like to apply 2-Dimensional Fourier Transform to a
square 63 x 63 pixels image. I made a bit a bibliography about this whole
thing, it is possible to express the output periodogram in polar form (i.e. instead
of Ipq values with 1 < p < 31 and -31 < q < 31 I would
have Irθ values with r = sqrt (p2 + q2) and θ
= tan-1 (p/q)), this allow me to average the Irθ values
among all θ directions and end up with only Ir values. However to
make some tests on the spectrum, I have to know how many θ directions I have
averaged per Ir values (basically, all the directions possible for
the pattern length “r”) but I cannot find a way to calculate or find out this
number. So my question is, do one of you know how to compute the directions
(never did FT by hand…) or is there any formula that would give the number of directions
for a given image size… don’t know if I made myself clear. 

 

Thanks 

 

With regards  





      
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