Human palm-vein is a permanent and unique physiological feature for each person. It hides under the skin and is difficult to duplicate because of its complex structure. Furthermore

palm vein images are difficult for candid shootings. All these characteristics make palm-vein a high security biometric feature. As a leading subject of biometrics technology

palm-vein image recognition has a wide prospect of application for its outstanding characters

such as high security. Palm vein image recognition has always been a research focus in recent years. This paper introduces the principle of palm-vein imaging first

then it provides a survey of the four stages for palm-vein image recognition: image acquisition

image preprocessing

feature extraction

and matching algorithms. According to different feature extraction approaches

we roughly group these algorithms into three categories: structure based

texture based

and subspace based methods. Finally

we conclude this paper describing the difficulty of palm-vein recognition technology and a discussion of future trends.