An embedded DCT-based still image coding algorithm

摘要

In a method and device for receiving a digitised compressed image comprising a region of interest (ROI), an embedded DCT-based (EDCT) image coding method is used. Decoded images having an improved PSNR are obtained by a scanning order starting, for each bitplane, from the upper left corner of a DCT block (corresponding to the DC coefficient) and a transmission of the coefficients in an order of importance. An embedded bit-stream is produced by the encoder, and the decoder can cut the bit-stream at any point and therefore reconstruct an image at a lower bitrate. The quality of the reconstructed image at this lower rate is the same as if the image was coded directly at that rate. Near lossless reconstruction of the image is possible, up to the accuracy of the DCT coefficients. The algorithm is very useful in various applications, like WWW, fast browsing of databases, medical imaging, etc.