[Numpy-discussion] Sobel question

Bob Klimek klimek at grc.nasa.gov
Wed Nov 10 13:54:02 CST 2004


I recently started playing with numarray and especially nd_image for 
processing grayscale and RGB images. nd_image looks very interesting and 
I'm looking forward to checking.

My question deals with the axis parameter of the Sobel filter. What does 
the function return when axis=-1?

I figured out that when axis=0, the function returns the vertical 
gradient component and when axis=1 the horizontal gradient component. 
Since -1 is the default I expected that it would return the gradient 
magnitude (sqrt(x*x + y*y)) but that's not the case.


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