Image coding with overlapped projection and pyramid vector quantization

A new effective still image coding scheme based on overlapped projections and pyramid vector quantization is presented. In standard image coding the spatial redundancy of the images is reduced subdividing the incoming data into small blocks and applying to these a linear transformation (DCT) to obtain highly independent coefficients, that are scalar quantized. This block by block coding takes advantage of the spatial correlation but it induces visually annoying blocking artifacts (especially at high compression ratios). The authors resent a different coding scheme where the image is subdivided into circular partially overlapped regions and then the projections along predefined directions are determined and vector quantized. Simulations show that the projection technique allows the detection of the most important information locally present on the image while the use of circular overlapped regions reduces blocking artifacts