[Numpy-discussion] image correlations

Todd Miller jmiller at stsci.edu
Fri May 21 12:50:04 CDT 2004


On Fri, 2004-05-21 at 15:01, John Hunter wrote:
> I have a series of luminance images that I want to do some correlation
> analyses on.  Each image is an MxN frame of a movie.  I want to
> compute the correlation between a given pixel i,j, and every other
> pixel in the image over each frame.  That is, if I assume
> xij is a numFrames length time series, and xkl is another numFrames
> length time series (the pixel intensities at two points in the image
> over time), I want to compute the 
> 
> corrcoeff(xij, xkl) for every kl with ij fixed.
> 
> I know I could do this by looping over the pixels of the image, but
> I'm hoping for something a bit faster.
> 
> Any suggestions?

For numarray try numarray.convolve.correlate2d and set fft=1.

Todd





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