Orientation accuracy of edge detection operators acting on binary and saturated grey-scale images

The orientation accuracy of a general class of edge detection operator acting on binary and saturated grey-scale images is studied. An operator similar to the Sobel operator is found to have the best available accuracy, of about +or-9.6 degrees , which is remarkably close to the figure of +or-1.2 degrees for grey-scale images. In addition, performance necessarily degrades gracefully in the presence of noise.