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This thesis proposes an automatic facial expression recognition system usinga neural network classifier. First, we use rough contour estimation routine, mathematical morphology, and point contour detection method to extract the precise contours of the eyebrows, eyes, and mouth of a face image. Then we define 30 facial characteristic points to describe the position and shape of these three organs. Because facial expressions can be described by combining different action units, which are used for describing the basic muscle movement of a human face, we choose six main action units, being composed of facial characteristic points movements, as the input vectors for three different neural network-based expression classifiers including radial basis function network, back-propagation network, and conceptual fuzzy sets. Using radial basis function network and
back-propagation network, we have obtained the same recognition rate as high as 92.2\%. Using conceptual fuzzy sets, we have obtained lower recognition rate of 60.5\%. Simulation results by computers demonstrate that computers are capable of extracting high-level or abstract information like human.
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