[SciPy-Dev] scipy.signal.correlate2d extremely slow

Malcolm Reynolds malcolm.reynolds@gmail....
Mon Mar 5 10:57:40 CST 2012


I've been compiling numpy and scipy from source for a while, and as
far as I was aware everything was configured correctly. However I
noticed today that scipy.signal.correlate2d is enormously slow,
several orders of magnitude slower in that it takes many minutes to
compute the correlation for two 216x384 matrices. For the same size
matrices, matlab's normxcorr2 (which I know is not entirely
equivalent, due to the added normalisation, but much of the
computation is analogous surely?) takes under half a second.

Is this a known issue with the underlying algorithm, or does it
indicate that my scipy has not linked correctly with some optimised
routines from atlas / blas / etc, or that I have made some other
mistake in the compilation?

Any help on this issue would be appreciated, I was relying on being
able to compute 2d cross correlations pretty fast.. Thanks!


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