Scaling method for linear-phase lattice filters for multiresolution image coding
P. Desneux, J. Y. Mertes, Benoit M. M. Macq, Jean-Didier Legat · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1994
Subband coding is one of the most used techniques for image compression. The coding consists in splitting the image into different frequency bands. These subbands are then coded independently from each other, the most part of bits being allocated to the subbands containing the most part of the energy. The subband decomposition is usually achieved by signal filtering. Multiresolution transform represents such a filtering technique. In most cases, filter design and optimization does not take hardware implementation constraints into account. However, these can lead to a loss of performances in the compression algorithms due to roundoff noise or coefficient quantization. In this article, we show the influence of finite precision effects on results achieved with a multiresolution architecture, using a transform based on separable linear-phase filters implemented in their lattice form. We also propose a scaling method which tries to minimize the computation noise and to avoid overflows. This scaling method has been simulated and gives useful results for the design of an integrated circuit implementing the multiresolution transform.