An overview of lossless digital image compression techniques

Lossless compression is necessary for many high performance applications such as geophysics, telemetry, nondestructive evaluation, and medical imaging, which require exact recoveries of original images. Lossless image compression can be always modeled as a two-stage procedure: decorrelation and entropy coding. The first stage removes spatial redundancy or inter-pixel redundancy by means of run-length coding, SCAN language based methodology, predictive techniques, transform techniques, and other types of decorrelation techniques. The second stage, which includes Huffman coding, arithmetic coding, and LZW, removes coding redundancy. Nowadays, the performances of entropy coding techniques are very close to its theoretical bound, and thus more research activities concentrate on decorrelation stage. JPEG-LS and JPEG-2000 are the latest ISO/ITU standards for compressing continuous-tone images. JPEG-LS is based on LOCO-I algorithm, which was chosen to incorporate the standard due to its good balance between complexity and efficiency. Another technique proposed for JPEG-LS was CALIC. JPEG-2000 was designed with the main objective of providing efficient compression for a wide range of compression ratios.