ADPCM encoding of images using a conjugate gradient based adaptive algorithm

A new recursive conjugate gradient (RCG) algorithm is developed for two-dimensional (2-D) adaptive differential pulse code modulation (ADPCM). This algorithm is based on the conjugate gradient method of optimization and therefore has a fast convergence characteristic. The RCG operates on samples of data rather than blocks, and is computationally simpler than the recursive least square (RLS) algorithm. Simulation results illustrate the efficiency of the method in ADPCM encoding of images.