David A Bowles

US Patent:

45258597, Jun 25, 1985

Filed:

Sep 3, 1982

Appl. No.:

6/414586

Inventors:

Romald E. Bowles - Silver Spring MD
David E. Bowles - Columbia MD

International Classification:

G06K 900

US Classification:

382 5

Abstract:

A pattern recognition system which detects line bifurcations and line endings, denoted minutiae, in a pattern of lines such as are found in a fingerprint is disclosed. In one embodiment, an image of a pattern is focused on a conventional matrix of image sensors or pixels. An interface circuit serially reads the voltages from the pixels and applies them to an automatic, programmable threshold detector which optimally selects a cutoff voltage and outputs a binary signal representative of the presence of a point to a minutiae detection circuit. One part of this circuit electrically reforms the matrix on a first-in-first-out basis and simultaneously forms a smaller submatrix or window. Another part of the detection circuit determines firstly if a point is present in the central array of the window, and if so, secondly whether no more than two points, which are also contiguous, are present in the peripheral part of the submatrix. In such a case, a minutia has been located and a memory stores the address of the window.