🚀 go-pugleaf

lake@cwjcc.INS.CWRU.Edu (Dr. Robin Lake) writes:


>One thing to watch out for is where the DC component of the 2-D FFT ends
>up in the result.  Very likely to be at the "corners" of the resulting
>array, requiring some reorganization to move to the "center".

What's wrong with the left upper corner? Index (0,0) is where it belongs.
If you want to somehow have a "logical" order with 0 in the middle, remember
that a frequency component of -1/N Hz is ABSOLUTELY indestinguishable
from (N-1)/N Hz due to sampling aliasing. The transform is based on
that fact (at least the fast algorithms), and why mangle up the indexing?

The only problem MAY be that people find graphical representations
of convolution masks or transforms irritating. I can live with that.
If you want to,
DISPLAY it shifted by whatever you want, but do not mangle the data
structure, because that tends to COMPLICATE things instead of making
them easier, especially since all the theorems of DFT are usually
formulated for indexes 0..N-1.