Rate-distortion modeling of binary shape using state partitioning

In this paper, the rate-distortion (R-D) characteristics of binary shapes are modeled. Specifically we are interested in predicting the rate and distortion that is produced by the shape coding techniques that have been adopted into the MPEG-4 standard. The shape coding algorithm is a context-based arithmetic encoder and operates on a per block basis. Currently, there is no efficient way of estimating the rate and distortion at various levels of resolution. Consequently, we propose a model that is based on a set of parameters that can be easily extracted from the binary blocks. The parameters represent states that arise from the possible binary patterns that can occur in a small neighborhood around the current pixel. Symmetry is exploited to keep the number of states to a minimum. It is shown that the proposed model is computationally efficient and provides accurate estimates of the R-D characteristics of a binary shape.