The technique of motion vector estimation can remove the information of temporal redundancy to reduce the bit rate for video coding. Due to the great computation required in motion vector estimation, many simplified search algorithms have been proposed. In particular, one-bit transform scheme can significantly reduce the search complexity. This paper proposes a dynamic threshold scheme to form the binary images with respective to each macro-block images. Motion vectors are calculated through a series of Boolean operations, such as ldquoXORrdquo, ldquoANDrdquo, and/or ldquoORrdquo. The experimental results show that better improvement on the coding quality can be achieved.