PostScript (261 KB)Motion Adaptive Model-Assisted Compatible Coding with Spatio-Temporal Scalability
Proceedings, Visual Communications and Image Processsing Conference, San Jose, California, February 1997
Abstract
We introduce the concept of Motion Adaptive Spatio-Temporal Model-Assisted Compatible (MA-STMAC) coding, a technique to selectively encode areas of different importance to the human eye in terms of space and time in moving images with the consideration of object motion. Previous STMAC was proposed based on the fact that human "eye contact" and "lip synchronization" are very important in person-to-person communication. Several areas including the eyes and lips need different types of quality, since different areas have different perceptual significance to human observers. The approach provides a better rate-distortion tradeoff than conventional image coding techniques based on MPEG-1, MPEG-2, H.261, as well as H.263. STMAC coding is applied on top of an encoder, taking full advantage of its core design. Model motion tracking in our previous STMAC approach was not automatic. The proposed MA-STMAC coding considers the motion of the human face within the STMAC concept using automatic area detection. Experimental results are given using ITU-T H.263, addressing very low bit rate compression.