Design of predictive vector quantizer for image coding
Due to the prediction loop, instability is a major difficulty in the design of a predictive quantizer. The conventional open-loop method enjoys good stability but suffers from poor performance. In contrast, the closed-loop method may be able to perform better but it can not guarantee a complete convergence and so it is unstable. Recently, the asymptotic closed-loop approach was proposed to benefit from the stability of open-loop design while asymptotically optimizing the actual closed-loop system. In this work, all of the above three design algorithms for predictive quantization are discussed and applied to image coding. Based on the analysis of simulation results, modifications to closed-loop design and asymptotic closed-loop design are proposed for further improvement in design quality and reliability.