Abstract: In this paper, two fast algorithms of BLI correlation are proposed. One is based on the accumulative difference vector and the other is based on the use of run-length encoding. Their computational complexity is analyzedand it is proved that the proposed fast algorithms can efficiently reduce the computation for correlationcalculation. An interpretation of the continuity and unicity principles is also given for the stereo vision by BLI correlation.These methods are tested for real images and the experimental results show the efficiency of the proposedmethods.