Boundary tracking method and apparatus to find leads
First Claim
1. An apparatus for finding dimensions of an object in an image, in an image processing system having a binary boundary tracker comprising:
- a threshold selection tool for analyzing an element of said object, said element having known dimensions, to obtain a threshold grey value;
said binary boundary tracer coupled to said threshold selection tool for generating signals representative of the coordinates of the boundary of said object using said threshold grey value to self-calibrate; and
an angle finder for obtaining angles of selected segments of said boundary of said object and generating histogram data therefrom, said angle finder including a feature analyzer for obtaining candidate corners of said object having changing angles from a first segment to a second segment in excess of an angle threshold, and for analyzing the geometric properties of said candidate corners for correspondence to features being sought so that the dimensions of said candidate corners in said image can be determined, measured and reported to a host controller.
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Accused Products
Abstract
A system to find wirebonded leads by obtaining an image of the crescent formed on a lead after wire bonding, or a difference image (taken from an image of the lead before bonding and the crescent and wire formed after bonding) to create an intermediate image having the desired rotation and registration characteristics. Using a caliper or other wire-finding tool, the invention locates the wire and generates a threshold value for a boundary tracker that will make the located wire the expected width. An alternative preferred embodiment uses the gray value of an edge of the wire as the threshold. An optional artificial boundary is created as a limit for a boundary tracker. The invention then applies a boundary tracker to the intermediate image using the threshold value generated and any artificial boundary created. It then applies a corner finder that restricts starting corner orientations and analyzes the boundary and its features to find crescent tips and extrema to obtain measurements for inspection.
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Citations
12 Claims
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1. An apparatus for finding dimensions of an object in an image, in an image processing system having a binary boundary tracker comprising:
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a threshold selection tool for analyzing an element of said object, said element having known dimensions, to obtain a threshold grey value; said binary boundary tracer coupled to said threshold selection tool for generating signals representative of the coordinates of the boundary of said object using said threshold grey value to self-calibrate; and an angle finder for obtaining angles of selected segments of said boundary of said object and generating histogram data therefrom, said angle finder including a feature analyzer for obtaining candidate corners of said object having changing angles from a first segment to a second segment in excess of an angle threshold, and for analyzing the geometric properties of said candidate corners for correspondence to features being sought so that the dimensions of said candidate corners in said image can be determined, measured and reported to a host controller. - View Dependent Claims (2, 3, 4, 5)
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6. A method of finding dimensions of an object in an image, in an image processing system having a binary boundary tracker comprising the steps of:
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analyzing an element of said object, said element having known dimensions, to obtain a threshold grey value; applying said binary boundary tracker for generating signals representative of the coordinates of the boundary of said object using said threshold grey value to self-calibrate; and applying an angle finder for obtaining angles of selected segments of said boundary of said object and generating histogram data therefrom, said angle finder including a feature analyzer for obtaining candidate corners of said object having changing angles from a first segment to a second segment in excess of an angle threshold, and for analyzing the geometric properties of said candidate corners for correspondence to features being sought so that the dimensions of said candidate corners in said image can be determined, measured and reported to a host controller. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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Specification