| 摘要 |
<p>A fingerprint classification and identification method and apparatus including circuitry to analyze a fingerprint image in the form of an N x M matrix of data elements, such data being analyzed in three basic scan windows which are clocked through a matrix array of data elements each containing either intensity data, direction data or both. The first window and its associated circuitry (114,140,200,220) serve to estimate data element directions by analyzing the intensity data in selected direction slits in the window to establish the slit having the ieast summed contrast between data elements spaced apart in the slit by a selected number of data elements. or to establish that there does not clearly exist such a slit. The second window passes through the matrix such that its data elements have already been passed through the circuitry (114,140,200,220) associated with the preliminary direction estimate window and have a preliminary direction estimate of one of the slit directions or "no direction". This second window and its associated circuitry (114,230) enhance the direction estimates made during passage of the first window according to various logic tests which generally seek to identify a slit direction which, along with the directions adjacent to it, are the directions of the predominant number of data elements in the window, or which is the average of the two slit directions which comprise the largest and second largest number of data elements, if they are sufficiently close in direction. The final window examines data elements having enhanced directions and with its associated circuitry (240,210,114), enhances the intensity data of a center data element in the third window, provided the center data element has an enhanced direction other than "no direction", according to an analysis of the center data element and the neighboring slit data elements in the slit with the direction of the enhanced direction of the center data element. The center data element and the neighboring slit data elements are compared with each other for direction data and intensity data and are compared with a mean intensity value for the scan window to derive a correction value for the center data element intensity to arrive at an enhanced intensity value. Separate logic is used to enhance the center data element intensity when it has a direction of "no direction", after which the data is passed into classification and matching circuitry (161).</p> |
