Hi,
to extract edges of any direction, you just need to choose the right structuring element for a morphological opening. E.g. to extract vertical edges:
BWv = imopen(BW,[1 1 1]');
horizontal:
BWh = imopen(BW,[1 1 1]);
top left to lower right
BWd = imopen(BW,[1 0 0; 0 1 0; 0 0 1]);
and so on.
Hope this helps, W.
