人脸表情识别是模式识别领域中一个重要的研究方向。人脸表情识别包括：从背景图像中检测人脸、图像采集、对人脸图像进行预处理、PCA提取表情特征、表情识别。-Face recognition is an important research direction in the field of pattern recognition. Face recognition is made up of the following parts: face detection from the background images, preprocessing of face images, extraction of expression characteristic by PCA and facial recognition.