Method and apparatus for contextual data enhancement

Abstract

A fingerprint image enhancement and identification system, wherein image data in digital form, is 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. Using a least summed contrast method, the first window estimates data element directions by analyzing the intensity data in selected direction slits in the window to provide a preliminary direction estimate of a slit direction or 'no direction'. Thereafter, the second window passes through the matrix to process the preliminary direction estimates, and enhance the direction estimates to identify a slit direction which, along with the directions adjacent to it, are the directions of the predominate 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 enhances the intensity data of a center data element in the third window, by 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.