Fingerprint Image Enhancement Algorithms

Fingerprint recognition is currently one of the hottest biometricidentification technology, and it is of great significance for improving theaccuracy and reliability of the identity recognition. However, due to fingerprintwet and dry, press pressure and other reasons, the fingerprint image capturedoften contains broken ridge or blurred ridge, this seriously affects the accuracyof the fingerprint feature extraction and recognition. Therefore, in order toimprove the quality of the fingerprint image, the fingerprint enhancement mustbe performed. In this paper, fingerprint image enhancement algorithms havebeen deeply studied, the main work and innovations are as follows:A fingerprint image enhancement algorithm based on fingerprint directionalimage filtered by variable scale of filter is proposed. Firstly, the originalfingerprint image normalization and background segmentation are implemented.Then, for the direction is not accurate when the fingerprint directional image iscalculated using the slit method, an improved directional template is proposed toimproved the accuracy；for the noise in the fingerprint directional image, analgorithm of variable scale of filter is proposed to ensure the accuracy of thefingerprint directional image in each part of the fingerprint image. Lastly,fingerprint image binarization and enhancement is implemented by the methodcombined with fingerprint orientation information corrected. The experimentalresults show that the proposed algorithm improves the effect of the fingerprintimage enhancement.An adaptive fingerprint image enhancement algorithm based on frequencydomain filtering is proposed in this thesis. Since the fingerprint texture iscomposed of alternately parallel ridges and valleys, it has band characteristic.But in different spatial directions fingerprint spectrum is not consistent, and it isdifficult to get a satisfactory filter result if a fixed band-pass filter is used, so anadaptive fingerprint image enhancement algorithm based on frequency domainfiltering is proposed. In the algorithm proposed, the cut-off frequency of thisband-pass filter is adaptively calculated according to the fingerprint spectrum image to filter the fingerprint image. Then fingerprint directional image iscalculated and binarization processing is implemented to further improve thequality of the fingerprint image. Experiments show the validity of the proposedalgorithm.Finally, the algorithm proposed and the other three fingerprint imageenhancement algorithm are compared and analyzed. Experimental results showthat the algorithm proposed has obvious advantages.