Improved Chen-Smith image coder

An image compression system based on transform coding and zonal sampling is presented. It is based on the Chen-Smith coder, but with an improved technique for transform coefficient quantization and the replacement of the discrete cosine transform (DCT) by the lapped orthogonal transform (LOT). The system leads to signal-to-noise ratios that are from 1.5 to 2.0 dB above those obtained with the standard JPEG algorithm, for a wide variety of test images and compression rates.<>