| Summary: | 碩士 === 國立中央大學 === 通訊工程研究所 === 96 === Active Appearance Models (AAMs) is an image representation method for non-rigid visual object with both shape and texture variations. It is a model-based representation method, and it uses a mean vector and a linear combinations of a set of variation modes to represent a non-rigid object. By adjusting the coefficients of the linear combinations of the variation modes(model parameters), we can synthesize any non-rigid objects. With this, we can express facial expressions using a model-based approach. For the facial expression recognition, an AAMs search algorithm is required to find the optimum model parameters such that the synthesized expression is similar to the facial expression in images. In this paper, we propose a novel iterative AAMs search algorithm. It minimizes the error which measures the difference between a model and a test image. We only adopt the magnitude of the predicted change of the parameters from the traditional search algorithm. However we decide the direction of the change of the parameters by estimating the gradient of the error function at each iteration. Moreover we prevent the local minimum search of the error function at each iteration by disturbing the searched parameters.
Our experiments show that the proposed robust AAMs search algorithm reduced 36.41% location error of shape and 30.82% intensity error of texture of facial expressions related to the AAMs search algorithm.
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