Gradient Adjusted Predictor with Pseudo-Distance Technique for Lossless Compression of Color-Mapped Images

Color-mapped images are widely used in many applications. Unlike most of the color-mapped image compression techniques, which require two passes, the pseudo-distance compression technique requires one pass and runs in linear time. Recently, we showed that when a structured arithmetic coder is used, after a color-mapped image is transformed with a pseudo-distance technique, better compression gains can be achieved over GIF and Huffman coder. In this work, we show that further compression gains are possible when a Gradient Adjusted Predictor is employed along with the pseudo-distance technique.