Maximum Area Triangle Operator for Edge Detection

Abstract

Currently images are more often noisy than regular, and universal contour extraction operators are few. The purely discrete operators are rather crude and inaccurate, while the more precise operators, which relying on the continuous approach, are complicated and rather slow. Using the restriction of gray level images to 3 x 3 masks interpreted as 30 digital surfaces, we present a new way of computing exactly the normal vector, or gradient, at regular points. Despite the fact that regular points are seldom on a general image, we deduce from this theoretical result a new discrete contour extraction operator, based on max area triangles contained in 3 x 3 masks (the MAT operator), which yields high quality results, comparable with those of continuous operators. © 1997 SPIE and IS& T. [S 1017-9909(97)00204-3]