Image improvement, through the use of the Fourier transform property of lenses using various frequency blocking filters, was investigated to determine possible utilization of this technique to enhance low contrast fingerprint image characteristics. Ten basic fingerprint patterns were degraded in contrast and then used as the object t(x,y) in an optical spatial filtering setup. A series of frequency blocking filters were used in an effort to improve the degraded object image. Visual comparison of the filtered images obtained by using a double band frequency blocking filter, which produced the most satisfactory images, shows improved overall contrast. Random ridge enhancement was achieved, which varied from pattern to pattern, but at the same time, degradation also occurred randomly from smeared-out and blemished sections. Although overall enhancement was not achieved, the enhanced partial areas are typical of the type used in identification work using fingerprints.
Library of Congress Subject Headings
Fingerprints; Photographic optics; Images, Photographic
Department, Program, or Center
School of Photographic Arts and Sciences (CIAS)
Scherlowski, Ludwig, "Theory of Optical Spatial Filtering and its Application to Enhance Low Contrast Fingerprint Images" (1971). Thesis. Rochester Institute of Technology. Accessed from
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