1. A method for identifying a person using their finger-joint print including the outer skin around the proximal interphalangeal joint of a finger, the method comprising: capturing an image of the finger-joint print of the person; extracting a region of interest (ROI) image I ROI based on a local convexity property of the finger-joint print; extracting features representing the orientation of the lines in a finger-joint-print image from the ROI image I ROI using an extended Gabor phase coding scheme and the extracted features are represented in competitive code maps, wherein angular distance between the competitive code maps is compared with a reference set in a database to identify the person; and defining a ROI coordinate system to extract the ROI image I ROI by: cropping a coarse sub-image I coarse from the captured image; obtaining a corresponding edge image I edge from the coarse sub-image I coarse using a canny edge detector; coding the corresponding edge image I edge based on a local convexity property to obtain a convexity coding image I cc , such that each pixel on the corresponding edge image I edge is assigned a code to represent the local convexity of this pixel; obtaining a line X=x 0 to best classify “−1” and “1” pixels on the convexity image I cc ; and taking the line X=x 0 as the Y-axis of the ROI coordinate system and the line y = height ⁢ ⁢ of ⁢ ⁢ I coarse 2 as the X-axis.