关键词: 人脸识别, 四元数, 小波包变换, 二维主成分分析

Abstract: This paper proposes a novel face recognition algorithm based on Wavelet Packet Transform（WPT） and two-Dimensional Quaternion Principal Component Analysis（2D-QPCA）.Wavelet packet decomposition coefficients are combined to constitute the quaternion matrix，then 2D-QPCA is used to reduce dimensions and construct quaternion feature space.After that the space is divided into several sub-blocks，and each sub-block is classified according to the principle of the nearest neighbor.These sub-block classification results are voted to complete the ultimate face recognition.Compared with the traditional algorithm such as the PCA algorithm，experiment results on four face databases（Orl，Yale face database，etc）show that the proposed face recognition algorithm is superior and robust to the light and expression changes.

Key words: face recognition, quaternion, wavelet packet transform, two-dimensional principal component analysis