PROGRESSIVE IMAGE-CODING BY HIERARCHICAL LINEAR-APPROXIMATION

Progressive image coding is a useful feature for image databases, imag e communications, and multimedia information systems. Central to progr essive image coding is a multiresolution image pyramid. Quadtree-based recursive regular tessellation is a popular form of image pyramid. Bu t regular tessellation is often too rigid to capture the scene structu re of an image; consequently, it may not generate a compact image repr esentation. This paper proposes a scheme of hierarchical piecewise lin ear approximation as an adaptive image pyramid. A progressive segmenta tion-based image coder comes naturally from the proposed image pyramid . The new image pyramid is semantically more powerful than regular tes sellation while syntactically simpler than free segmentation. This goo d compromise between the adaptability and complexity of image segmenta tion contributes to high compression ratios achieved by our progressiv e image coder. In addition to its advantages in data compression and p rogressive transmission, our image coder also facilitates many other i mage manipulations.