Quantization of Content-adaptive Orthonormal Transforms using a Gauss-Markov Random Field Model for Images

Forward adaptive transform coding requires a codebook of transform matrices from which the best transform can be chosen for each macroblock in an image. Codebook construction involves designing a vector quantizer for a sample set of KarhunenLoeve transform (KLT) matrices. While several approaches to designing such matrix codebooks have been proposed in previous work [1] , [2] , these non-parametric methods carry out matrix quantization in very high dimensional spaces which can suffer from the curse of dimensionality. Furthermore, the resulting transform matrices are not scalable - if multiple transform block sizes are to be used, such as in video compression, a separate matrix codebook must be designed for each block size.