I. Introduction
Computer-Aided personal recognition is becoming increasingly important in our information-based society, and within this field biometrics is one of the most important and reliable methods [1], [2]. The most widely used biometric feature is the fingerprint [3], [4] and the most reliable feature is the iris [1], [5], [6]. However, it is very difficult to extract small unique features (known as minutiae) from unclear fingerprints [3], [4] and iris input devices are very expensive. Other biometric features, such as the face [7], [8] and the voice [9], [10], are as yet not sufficiently accurate. Compared with all of these, the palm print, a relatively new biometric feature, has several advantages [11]. Palm prints contain more information than fingerprints, so they are more distinctive. Palm print capture devices are much cheaper than iris devices. Further, palm prints contain additional distinctive features such as principal lines and wrinkles, which can be extracted from low-resolution images. By combining all the features of palms, such as palm geometry, ridge and valley features, and principal lines and wrinkles, it is possible to build a highly accurate biometrics system.