A phase decoding technique is proposed to solve the problem of phase retrieval from an optical interferogram that is overlaid with random noise and segmented discontinuity. The technique is on the basis of a composite mask matching combined with a special phase unwrapping algorithm. The computer aided analysis and experimental interferograms show that the technique can be quite efficient in phase unwrapping procedure for interferograms in which speckle noise or true phase discontinuities or both may exist.