A lossless image compression algorithm using predictive coding based on quantized colors

Abstract

Predictive coding has proven to be effective for lossless image compression. The predictive coding estimates true color of a pixel based on the true colors of its neighboring pixels. To enhance the accuracy of the estimation, we propose a new and simple predictive coding algorithm that uses the quantized colors of neighboring pixels to estimate the true color of a pixel. The estimation is based on the majority of quantized colors of the three neighboring pixels. Experiments, over a set of true color 24-bit images whose colors of pixels are quantized into 2, 4, 8 and 16 colors, show that the proposed algorithm outperforms some well known lossless image compression algorithms such as JPEG-LS and PNG by factors of two to three in terms of compression bit rates. From the results of the experiment, it can be shown that the proposed algorithm gives the best compression results when colors are quantized into two colors for most of the test images.