The expression generation is one of important research contents of intelligent human-computer interface.Because images are the research objects in the majority

the facial expression generation techniques based on the study method dont need to model for 3D faces and potentially can be of highly realistic expressions.These are of considerable advantages in reality improving and complexity reducing.Some methods can also be used to 3D models.The paper summarizes the published researches from the aspects of morphing

expression mapping

statistical method

2D meshes

facial color expression and performance-driven.The conceptions

principals and the methods of typical achievements are discussed.The features and existing problems of different algorithms as well as the development trend are analyzed.It provides some useful information and gives a reference to related works.