Fast high-accuracy multi-dimensional pattern inspection
First Claim
1. A method for forming chains of edgelets, the edgelets being disposed within a two-dimensional array, each edgelet having a position and a direction, the method comprising:
- for each edgelet, providing a data structure including data slots for storing;
edgelet position, edgelet direction, a right link to a right-neighboring edgelet, and a left link to a left-neighboring edgelet;
for each edgelet at a position in the two-dimensional array, examining neighboring positions in two phases so as to determine which neighboring positions contain a neighboring edgelet which can be connected to the edgelet at the position, a first phase for identifying a right-neighboring edgelet, and a second phase for identifying a left-neighboring edgelet, each phase including examination of an equal number of different neighboring positions; and
for each edgelet, storing from the first phase one of a right link and a null link in a first data slot of the data structure of the edgelet, and storing from the second phase one of a left link and a null link in a second slot of the data structure of the edgelet, thereby forming at least one chain of edgelets.
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Abstract
A method and apparatus are provided for identifying differences between a stored pattern and a matching image subset, where variations in pattern position, orientation, and size do not give rise to false differences. The invention is also a system for analyzing an object image with respect to a model pattern so as to detect flaws in the object image. The system includes extracting pattern features from the model pattern; generating a vector-valued function using the pattern features to provide a pattern field; extracting image features from the object image; evaluating each image feature, using the pattern field and an n-dimensional transformation that associates image features with pattern features, so as to determine at least one associated feature characteristic; and using at least one feature characteristic to identify at least one flaw in the object image. The invention can find at least two distinct kinds of flaws: missing features, and extra features. The invention provides pattern inspection that is faster and more accurate than any known prior art method by using a stored pattern that represents an ideal example of the object to be found and inspected, and that can be translated, rotated, and scaled to arbitrary precision much faster than digital image re-sampling, and without pixel grid quantization errors. Furthermore, since the invention does not use digital image re-sampling, there are no pixel quantization errors to cause false differences between the pattern and image that can limit inspection performance.
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Citations
30 Claims
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1. A method for forming chains of edgelets, the edgelets being disposed within a two-dimensional array, each edgelet having a position and a direction, the method comprising:
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for each edgelet, providing a data structure including data slots for storing;
edgelet position, edgelet direction, a right link to a right-neighboring edgelet, and a left link to a left-neighboring edgelet;for each edgelet at a position in the two-dimensional array, examining neighboring positions in two phases so as to determine which neighboring positions contain a neighboring edgelet which can be connected to the edgelet at the position, a first phase for identifying a right-neighboring edgelet, and a second phase for identifying a left-neighboring edgelet, each phase including examination of an equal number of different neighboring positions; and for each edgelet, storing from the first phase one of a right link and a null link in a first data slot of the data structure of the edgelet, and storing from the second phase one of a left link and a null link in a second slot of the data structure of the edgelet, thereby forming at least one chain of edgelets. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification