Robinson compass mask
A Robinson compass mask is a type of mask which is used for edge detection. It has eight orientations. It is also known as the direction mask. It extracts the edges with respect to its direction. Following are its eight orientations:
It does not have any fixed mask. We have to rotate the mask to find an edge in any one direction above mention. Masks are rotated from zero columns on the basis of direction.
Following is a mask which is in north direction and the rotated:
Example of Robinson compass mask applied to an image