A PERCEPTUALLY MOTIVATED 3-COMPONENT IMAGE MODEL .2. APPLICATIONS TO IMAGE COMPRESSION

In this paper, the use of the image model of Part I is investigated in the context of image compression, The model decomposes the image into a primary component that contains the strong edge information, a smoo th component that represents the background slow-intensity variations, and a texture component that contains the textures, The primary compo nent, which is known to be perceptually important, is encoded separate ly by encoding the intensity and geometric information of the strong e dge brim contours, Two alternatives for coding the smooth and texture components are studied: entropy-coded adaptive DCT and entropy-coded s ubband coding, It is shown via simulations that the proposed schemes, which can be thought of as a hybrid of waveform coding and feature-bas ed coding techniques, result in both subjective and objective performa nce improvements over several other image coding schemes and, in parti cular, over the JPEG continuous-tone image compression standard. These improvements are especially noticeable at low bit rates, Furthermore, it is shown that a perceptual tuning based on the contrast-sensitivit y of the human visual system can be used in the DCT-based scheme, whic h in conjunction with the three-component model, leads to additional s ubjective performance improvements.