ABSTRACT
This chapter presents a comprehensive characterization of the numerous coding artifacts which are introduced into reconstructed video sequences through the use of the hybrid motion compensation/Differential Pulse Code Modulation/Discrete cosine transform (DCT) algorithm. It identifies the distortions which have a consistent identifying characteristic and, hence, may be labeled as a consequence of the quantization process rather than a natural characteristic of the source. The visual characteristics of the DCT basis images may also produce other coding artifacts when adjacent blocks are taken into consideration. A comprehensive classification will also assist in the design of more effective adaptive quantization algorithms, coding mechanisms and post-processing techniques under the current constant bit-rate schemes, and, therefore, improve video codec performance. To account for the adaptive quantization mechanisms and human visual system masking properties utilized in practical coding applications, an Moving Picture Experts Group-1 compliant codec, utilizing source content-based adaptive bit-allocation, will be employed as the origin of the coding distortions.
