The human visual system is highly space variant in sampling, coding, processing and understanding. The spatial resolution of HVS is highest around the point of fixation and decreases with increasing eccentricity. By taking advantages of this possible fact, we can remove considerable high frequency information redundancy from peripheral regions and still construct a good quality image. Great success has been obtained recently by a class of embedded wavelet image coding algorithms, such as the embedded zero tree wavelet (EZW) and set portioning in hierarchical trees algorithms (SPIHT). Embedded wavelet coding not only provides very good compression performance but also has the property that the bit stream can be truncated at any point and still is decoded to recreate a reasonably good quality image.

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