Combined Lossless/Lossy Compression of Three-channel Images

This paper deals with the compression of three-channel images that offers near-lossless and lossless options. The lossy compression is based on discrete atomic functions. They provide several benefits such as easy control of introduced distortions, privacy protection, and quite efficient compression. Lossless mode is provided due to archiving the differences between the original and lossy compressed images. An increase in a compression ratio of the lossy compression part leads to larger differences and worse lossless compression. Due to this, an optimum has to be found. We look for this optimum using a set of color images of different complexity. It is shown that the maximal compression ratio of lossless compression is achieved for traditional modes of atomic compression when the peak signal-to-noise ratio of the lossy compressed part is about 40-42 dB, i.e. practically near-lossless or visually lossless compression is carried out.