Np. Chandrasiri et al., Real time facial expression recognition system with applications to facialanimation in MPEG-4, IEICE T INF, E84D(8), 2001, pp. 1007-1017
This paper discusses recognition up to intensities of mix of primary facial
expressions in real time. The proposed recognition method is compatible wi
th the MPEG-4 high level expression Facial Animation Parameter (PAP). In ou
r method, the whole facial image is considered as a single pattern without
any block segmentation. As model features, an expression vector, viz. low g
lobal frequency coefficient (DCT) changes relative to neutral facial image
of a person is used. These features are robust and good enough to deal with
real time processing. To construct a person specific model, apex images of
primary facial expression categories are utilized as references. Personal
facial expression space (PFES) is constructed by using multidimensional sca
ling. PFES with its generalization capability maps an unknown input image r
elative to known reference images. As PFES possesses linear mapping charact
eristics, MPEG-4 high level expression FAP can be easily calculated by the
location of the input face on PFES. Also, temporal variations of facial exp
ressions can be seen on PFES as trajectories. Experimental results are show
n to demonstrate the effectiveness of the proposed method.