I. Introduction
With the requirement that a single video bitstream should flexibly provide several different spatial resolutions to satisfy various channel conditions and customers with different bitrate, computational, and power capabilities, spatial scalability has become an attractive feature in many video applications. The video bitstream is desired to be partitioned in such a way that the base layer is decoded independently to form a lower resolution sequence, and the enhancement layers, which contain additional refinement data, can be decoded to provide higher resolutions.