| 摘要 |
A method and automatic system (Fig. 1) for extracting both ordinary and unique features of a stripe pattern like a fingerprint from a gray level image without binary processing. A precise direction array (fig. 3) with the same number of image points as the image is generated by calculating the average direction of local ridges for every point in the image with a quick recurrent algorithm. There is also generated a curvature array in which each element presents the accuracy of the local average direction at corresponding points in the direction array and image. A region of clear ridges extracted from background and noise before detecting image features. The ridge trends (Figs. 8a-8e) and forkedness of a point are decided by analyzing the distribution of ridge directions on a circle around the point. For finding the cores and deltas, trend analysis is used for each singularity that is a maximum point on the curvature array. The coordinate axis that is consistent for various fingerprint types is decided by analyzing the structure of the direction array macroscopically. |
