Optics and Lasers in Engineering 37 (2002) 51–62 Fringe skeletonizing using an improved derivative sign binary method

A modified derivative sign binary method is proposed to extract fringe skeletons from interferometric fringe patterns. A fringe direction map ranging from 01 to 3601 is obtained with an unambiguous relationship between the grayscale and fringe tangent direction. Using this approach, the derivative sign binary map is detected without a fringe direction jump. The dark (light) fringe intensity minimum (maximum) can be extracted automatically to define fringe skeletons. In addition, two different anisotropic one-dimensional filters are described that can be used for further improving the fringe quality. Examples are provided for a holographic interferogram and a Moir!e fringe pattern to illustrate applications and benefits o