Interactive model-based coding of facial image sequence with a new motion detection algorithm

To make the model-based coding a practical method, new signal processing techniques other than fullyautomatic image recognition should be studied. Also after having realized the model-based coding, another new signal processing technique to improve the performance of the modelbased coding should be studied. Moreover non-coding functions related to the model-based coding can be embedded as additional features. The authors are studying the interactive model-based coding in order to achieve its practical realization, improve its performance and extend related non-coding functions. We have already proposed the basic concept of interactive model-based coding and presented an eyeglasses processing for a facial image with glasses to remove the frame for improving the model-based coding performance. In this paper, we focus on the 3-D motion detection algorithm in the interactive model-based coding. Previous works were mainly based on iterative methods to solve non-linear equations. A new motion detection algorithm is developed for interactive model-based coding. It is linear because the interactive operation generates more information and the environment of the applications limits the range of parameters. The depth parameter is first obtained by the fact that a line segment is invariant as to 3-D space transformation. Relation of distance between two points is utilized. The number of conditions is larger than that of the unknown variables, which allows to use least square method for obtaining stable solutions in the environment of the applications. Experiments are carried out using the proposed motion detection method and input noise problems are removed. Synthesized wireframe modified by eight parameters provides smooth and natural motion.