A directional extension of the JPEG image codec

A simple directional extension of the JPEG standard is proposed, which consists in rearranging pixels in 8 × 8 blocks before the DCT-based transform coding, and then restoring the original pixel positions before putting reconstructed blocks into the decoded image buffer. Pixels are shuffled so as to improve block reconstruction accuracy and/or to decrease the number of bits to be put into a JPEG-compliant bit stream. For numerous pictures, such a straightforward adapting a signal to a transform gives evident gains in compression efficiency over the original JPEG. Even though the more advanced known algorithms offer better results, the presented solution requires less computations and memory and is more hardware friendly.