[SciPy-User] Numpy/Scipy: Avoiding nested loops to operate on matrix-valued images

tyldurd dhondt.olivier@gmail....
Thu Mar 15 03:59:28 CDT 2012



Hello,

I am a beginner at python and numpy and I need to compute the matrix 
logarithm for each "pixel" (i.e. x,y position) of a matrix-valued image of 
dimension MxNx3x3. 3x3 is the dimensions of the matrix at each pixel.

The function I have written so far is the following:

def logm_img(im):
    from scipy import linalg
    dimx = im.shape[0]
    dimy = im.shape[1]
    res = zeros_like(im)
    for x in range(dimx):
        for y in range(dimy):
            res[x, y, :, :] = linalg.logm(asmatrix(im[x,y,:,:]))
    return res

Is it ok? Is there a way to avoid the two nested loops ?
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