Image data compression methods to improve the efficiency of image transmission and storage can be classified in two basically different categories : intraframe and interframe codings. The former is to exploit the spatial redundancy, while the latter is to reduce the frame-to-frame redundancy. The emphasis of this work is on the interframe coding methods, especially simple systems such as partitioned hybrid coding and motion-compensated coding.
Interframe 3-D DCT and 2-D DCT/DPCM codings are shown to have superior performance but higher system complexity to the intraframe codings. Based on a generalized 3-D covariance model, the performance of various coding methods is compared to 3-D RDF (rate distortion function), and the usefullness of the model for 3-D real image sequences is shown.
At low bit rates below 1.0 bit/pel, the partitioned hybrid coding is found to be an effective method for slowly changing image sequences. The coding performances are compared for the conditional replenishment method and the motion-compensated DPCM method.
