Variable Block Rate and Blockwise Spectral Adaptation in Cosine Transform M2.6
William A. Pearlman · 1988
A block DCT coding scheme is implemented with a different rate assignment to each block for the purpose of maintaining a constant distortion per block. A spectral estimate is calculated for every block. Overhead rate and computation for adaptation are kept to a reasonable level through characterization of the block's estimated spectrum by a one-dimensional auto-regressive model. Simulations with natural and multi-modality medical images provide reconstructions with nearly uniform block distortion and very high visual and measurable quality at low rates.