Image analysis – Applications – Biomedical applications
Patent
1993-12-22
1996-02-13
Razavi, Michael T.
Image analysis
Applications
Biomedical applications
382291, 348 78, 351210, A61B 3024, G06K 978
Patent
active
054917573
ABSTRACT:
A field test apparatus and method is disclosed in which gradual movement of the head supporting chin cup is used to maintain a centered relation between the eye being tested and the trial lens frame holding the required prescription for optimum vision of the patient. During the test, alternating illumination is provided in the infrared between a central corneal reflection and an iris illuminating source which imparts a high contrast bright circular iris image surrounding a central dark pupil. Content addressable memories are used to delineate areas of contrast change for rapid and abbreviated microprocessor analysis of conventional RAM images. Both the corneal reflection image--which is a brightly illuminated spot on an otherwise dark background--and the pupillary image--which is a dark pupil surrounded by a brightly illuminated high contrast image of the iris are approximately located at their boundaries using content addressable memory. Thereafter, conventionally stored video data is processed at locations restricted to the high contrast boundaries. For location of the pupil center, special techniques are disclosed for examining the image's first and second derivatives to establish the pupil center within sub-pixel limits. These methods include sufficient data processing speed improvements to enable a time shared use of a microprocessor having gaze angle measurement as a peripheral event to instrument control, and data collection required in such field testing.
REFERENCES:
patent: 1960111 (1934-05-01), Kirk
patent: 4145123 (1979-03-01), Krahn
patent: 4429961 (1984-02-01), Scheingorn
patent: 4748502 (1988-05-01), Friedman et al.
patent: 4854694 (1989-08-01), Hirano
patent: 4928260 (1990-05-01), Chuang et al.
patent: 4950069 (1990-08-01), Hutchinson
patent: 4973149 (1990-11-01), Hutchinson
patent: 5008946 (1991-04-01), Ando
patent: 5066117 (1991-11-01), Matsumura
patent: 5214456 (1993-05-01), Gersten
patent: 5220361 (1993-06-01), Lehmer
Myers, Glenn A., et al, "Eye Monitor", IEEE Journal, Mar. 1991, pp. 14-21.
ISCAN.RTM. Eye Movement Monitoring Research Laboratory, brochure, 1989.
Kirschbaum Alan R.
Lehmer Donald E.
Humphrey Instruments Inc.
Prikockis Larry J.
Razavi Michael T.
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