Edge peak contour tracker
First Claim
1. A method for finding an edge contour in an image, the edge contour including a sequence of contour points, the method comprising the steps of:
- determining the position of a current contour point by locating the peak of a first difference signal of a gray value signal using pixels of a pixel set extending across the edge contour;
advancing to determine the position of a next contour point using the position of the current countour point; and
returning to the step of determining the position of a current countour point, the next contour point becoming the current contour point.
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Accused Products
Abstract
A method and apparatus for finding an edge contour in an image of an object is provided that is robust against object/background misclassification due to non-uniform illumination across an image, while also being computationally efficient, and avoiding the need to select a classification threshold. The invention can be used to partition an image of a scene into object regions and background regions, or foreground regions and background regions, using edge contours found in the image. The invention is particularly useful for analysis of images of back-lit objects. The edge contour is progressively formed by finding a sequence of one-dimensional edge positions, each one-dimensional edge position being determined by processing a set of pixels arranged along at least one imaginary line.
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Citations
17 Claims
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1. A method for finding an edge contour in an image, the edge contour including a sequence of contour points, the method comprising the steps of:
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determining the position of a current contour point by locating the peak of a first difference signal of a gray value signal using pixels of a pixel set extending across the edge contour; advancing to determine the position of a next contour point using the position of the current countour point; and returning to the step of determining the position of a current countour point, the next contour point becoming the current contour point. - View Dependent Claims (2, 3, 4, 5)
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6. A method for finding an edge contour, the method comprising the steps of:
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determining the position and direction of an initial current boundary point; selecting a plurality of pixels along a first line that is non-parallel to the direction of said current boundary point; computing a first difference signal along said plurality of pixels; finding the position of a peak of said first difference signal; using said position of said peak to determine a position and direction of a new current boundary point; and returning to the step of selecting a plurality of pixels. - View Dependent Claims (7, 8, 9)
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10. A method for finding an edge contour in an image, the edge contour including a plurality of contour points, the method comprising the steps of:
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determining the position and direction of an initial current contour point; selecting a plurality of pixels along a first line through said current contour point that is non-parallel to the direction of said current contour point; computing an edge enhancement signal along said plurality of pixels; finding the position of a peak of said edge enhancement signal; using said position of said peak to determine a position and direction of a new current contour point; and returning to the step of selecting a plurality of pixels. - View Dependent Claims (11, 12, 13)
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14. An apparatus for finding an edge contour in an image, the edge contour including a plurality of contour points, the apparatus comprising:
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initial determining means for determining the position and direction of an initial current contour point; first selecting means, connected to said determining means, for selecting a plurality of pixels along a first line through said current contour point that is non-parallel to the direction of said current contour point; computing means, connected to said first selecting means, for computing an edge enhancement signal along said plurality of pixels; finding means, connected to said computing means, for finding the position of a peak of said edge enhancement signal; and new determining means, connected to said finding means and to said first selecting means, for using said position of said peak to determine a position and direction of a new current contour point. - View Dependent Claims (15, 16, 17)
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Specification