An algorithm for automatic extraction of contour lines from Moire image

Noise reduction is one of significant problems for Moire image processing. The detection of true con-tour lines in a noisy Moire image often requires to rejoint contours split by noises. We developed a recursive search method and a loop controlled method which identify the direction of short segment of lines in a small area to connect and repair contour lines. Unfortunately, these two mehtods can not connect contour lines without errors. When they accept human judgements, however, they are efficient and useful enough to find contour lines because the human effort to indicate whether to connect two lines or not is very slight. With these methods we can obtain contour lines more easily, faster, more accurately than before.