CMOS cameras are used more often nowadays to obtain planar information.To improve the tolerance of electromagnetic interference and measurement precision,they are utilized to measure in optical domain.Here three algorithms luminance extremum algorithm,point number comparison algorithm,and covered area comparison algorithm are proposed.With a proper design of a low-coherence fiber interferometer,these algorithms are tested experimentally.The result shows that covered area comparison algorithm is most efficient and the center fringe is marked accurately.In addition,it is suitable to real time information display systems.