DPCM is a lossless compression method used widely. A novel D 2PCM compression technique has been developed in this paper for more effective lossless compression of DSA (Digital Subtraction Angiography) image sequence

in which the correlation between subtraction images remains meaningful. By applying the lossless DPCM coder to the subtraction image

it constitutes a two order differential coding scheme in spatial and temporal space . This proposed method is able to sufficiently reduce the temporal spatial correlation. The high lossless compression ratio achieved by this technique will favor the transmission speed and storage space. The results in real applications prove it practicable and robust.