Rate-distortion optimized image coding allowing lossless conversion to JPEG compliant bitstreams

This paper proposes an efficient lossy image coding scheme which has a sort of compatibility with the JPEG standard. In this scheme, our encoder directly compresses an image into a specific bitstream. On the other hand, the reconstructed image is given by the standard JPEG decoder with a help of lossless bitstream conversion from the specific bitstream to the JPEG compliant one. This asymmetric structure of encoding and decoding procedures enables us to utilize modern coding techniques such as intra prediction, rate- distortion optimization and arithmetic coding in encoding process, while allowing almost all image manipulation software to directly import image contents without any loss of quality. In other words, the proposed scheme utilizes the JPEG compliant bitstream as an intermediate format for the decoding process. Simulation results indicate that the rate- distortion performance of the proposed scheme is better than those of the current state-of-the-art lossy coding schemes.