Fringe-orientation maps and fringe skeleton extraction by the two-dimensional derivative-sign binary-fringe method

The fringe-orientation information of an interferometric fringe pattern is provided in the form of a fringe-orientation map by spin filtering. The fringe-orientation information is an important feature of fringe patterns and is helpful in many fringe-pattern processing algorithms. With the help of a fringe-orientation map the two-dimensional derivative-sign binary-fringe method is developed to extract fringe skeletons from a fringe pattern with an arbitrary fringe distribution. This fringe skeleton extraction method does not require thresholds and a thinning process. It is relatively robust and highly accurate.