Image compression using conditioning contexts

A method for still image coding is proposed which allows for progressive transmission, because low detailed versions of the image can be reconstructed from a truncated bit stream. The proposed method is in its main aspects close to the classical pyramid approach of Burt and Adelson. 1 While retaining the main idea of using a Laplacian pyramid type decomposition, the new proposal differs in the filters employed for pyramid decomposition and in the bit allocation and quantization. The image is decomposed into a centered spline Laplacian pyramid. The pyramid is quantized and coded following a layered quantization approach together with a layered coding method based on conditional arithmetic coding. 2 The encoder outputs an embedded bit stream. Thus the decoder may truncate the bitstream at any point, which results in a more or less detailed image. Besides this rate-distortion scalability the coder has a multiresolution property, due to the pyramid decomposition. An extension to hybrid video coding is also discussed.