[Numpy-discussion] Sobel question

[Bob Klimek]

Hi,

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.

Bob