Image analysis – Applications – Manufacturing or product inspection
Patent
1995-03-17
1998-06-30
Couso, Jose L.
Image analysis
Applications
Manufacturing or product inspection
G06K 900
Patent
active
057745730
ABSTRACT:
A binary map of an object having edges is produced by first producing a digital grey scale image of the object with a given resolution, and processing the grey scale image to produce a binary map of the object at a resolution greater than said given resolution. Processing of the grey scale image includes the step of convolving the 2-dimensional digital grey scale image with a filter function related to the second derivative of a Gaussian function forming a 2-dimensional convolved image having signed values. The location of an edge in the object is achieved by finding zero crossings between adjacent oppositely signed values. Preferably, the zero crossings are achieved by an interpolation process that produces a binary bit map of the object at a resolution greater than the resolution of the grey scale image. The nature of the Gaussian function whose second derivative is used in the convolution with the grey scale image, namely its standard deviation, is empirically selected in accordance with system noise and the pattern of the traces on the printed circuit board such that the resulting bit map conforms as closely as desired to the lines on the printed circuit board.
The convolution can be performed with a difference-of-two-Gaussians, one positive and one negative. It may be achieved by carrying out a one-dimensional convolution of successive lines of the grey scale image to form a one-dimensional convolved image, and then carrying out an orthogonal one-dimensional convolution of successive lines of the one-dimensional convolved image to form a two-dimensional convolved image. Each one-dimensional convolved image may be formed by multiple convolutions with a boxcar function.
REFERENCES:
patent: 4048485 (1977-09-01), Nussbaumer
patent: 4259661 (1981-03-01), Todd
patent: 4303947 (1981-12-01), Stoffer
patent: 4330833 (1982-05-01), Pratt et al.
patent: 4442542 (1984-04-01), Lin et al.
patent: 4472786 (1984-09-01), Larson
patent: 4555770 (1985-11-01), Sage
patent: 4570180 (1986-02-01), Baier et al.
patent: 4578812 (1986-03-01), Yui
patent: 4658372 (1987-04-01), Witkin
Okuyama, H. et al., "High Speed Digital Image Processor With Special Purpose Hardware for Two-Dimensional Convoluting", Rev. Sci., Instrum., vol. 50, No. 10, Oct. 1979, pp. 1708-1712.
Edge and Region Analysis for Digital Image Data, Robert M. Haralick, pp. 60-73.
Superresolving image restoration using linear programming, R. Mammone and G. Eichmann, vol. 21, No. 3 Feb. 01, 1982, pp. 496-501.
A survey of Edge Detection Techniques, Larry S. Davis, (1975) pp. 248-270.
Precision bounds in superresolution processing, Lawrence S. Joyce and William L. Root, vol. 1, No. 2 Feb. 1984.
An Optimal Frequency Domain Filter for Edge Detection in Digital Pictures; K. Sam Shanmugan et al, IEEE Transaction on Pattern Analysis and Machine Intelligence, vol. PAMI-1, Jan. 1979. pp. 37-49.
Theory of Edge Detection; D. Marr et al, Proceedings of Royal Society, B207; pp. 187-217 (1990).
"Finding Edges and Lines in Images" by John F. Canny.
"Automatic Visual Inspection of PC Boards in Seconds", Published on May 1, 1984.
A Very High Speed, Very Versatile Automatic PCB Inspection System, By Shimon Ullman, Presented in Wash D.C., May 22-25, 1984.
Caspi Amiran
Smilansky Zeev
Couso Jose L.
Orbotech Ltd.
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