Application of method for getting direction image based on gradient in fingerprint preprocessing

The fingerprint image preprocessing is the premise and basis for fingerprint identification. It will directly influence the final outcome of fingerprint identification. In order to maintain and restore fingerprint ridge structures, and improve the noise immunity of fingerprint image preprocessing algorithm. In the paper, a method for getting direction image based on gradient is given. Using direction information of fingerprint image, we execute a sequence of operations, such as: image enhancement, binarization, thinning, and a more accurate linear graph is obtained. This method which is proposed in process of fingerprint preprocessing can effectively improve the quality of fingerprint ridge and can obviously restrain all kinds of noises. The experiment result shows that the method achieves the desired result.