充分利用数字减影（DSA）图象序列在时间域上的减影图象之间仍然存在一定的相似性，提出了一种基于二阶差分PCM（D＾2PCM）的编码方式。方法在空间坐标与时间坐标上构成了一个二阶差分，能够有效地减少图象在空间以及时间域上的冗余度，从而实现对DSA序列的无损压缩，减少了存储空间与传输时间。实际应用证明该处法是稳定和实用的。

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.