Transform coding for low-bit-rate applications
Dulce B. Ponceleon, Katherine S. Wang, Hsi-Jung Wu, James O. Normile · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1994
Low bit rate image coding at 10 kbit/s and less is a difficult problem and does not appear possible with the current generation of block transform based methods. Current research efforts center around the use of transforms with less objectionable artifacts such as wavelets or model based methods. We examine a method that is transform based but captures specific features of the image to be represented. The transform uses principal component analysis to generate a basis set specific to the particular class of images to be coded. We present results from a transform designed for use in a `talking head' sequence. Significant improvement in reconstructed quality is shown when perceptual weighting is used in generating the basis set. The appendix includes details of computationally efficient methods for deriving the basis set as well as a description of the weighting method.