Method and apparatus for segmenting small structures in images
First Claim
1. A method for segmenting a small feature in a multidimensional digital array of intensity values in a data processor, the method comprising:
- computing an edge metric along each ray of a plurality of multidimensional rays originating at a local intensity extreme;
identifying a multidimensional edge point corresponding to a maximum edge metric on each said ray;
labeling every point on each said ray from said local extreme to said edge point; and
labeling an unlabeled point if the unlabeled point is adjacent to a labeled point and the unlabeled paint has a more extreme intensity than the labeled point and the unlabeled point is closer than the labeled point to the local extreme.
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Abstract
A method for segmenting a small feature in a multidimensional digital array of intensity values in a data processor computes an edge metric along each ray of a plurality of multidimensional rays originating at a local intensity extreme (local maximum or minimum). A multidimensional point corresponding to a maximum edge metric on each said ray is identified as a ray edge point. Every point on each ray from the local extreme to the ray edge point is labeled as part of the small object. Further points on the feature are grown by labeling an unlabeled point if the unlabeled point is adjacent to a labeled point, and the unlabeled point has a more extreme intensity than the labeled point, and the unlabeled point is closer than the labeled point to the local extreme. The resulting segmentation is quick, and identifies boundaries of small features analogous to boundaries identified by human analysts, and does not require statistical parameterizations or thresholds manually determined by a user.
34 Citations
42 Claims
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1. A method for segmenting a small feature in a multidimensional digital array of intensity values in a data processor, the method comprising:
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computing an edge metric along each ray of a plurality of multidimensional rays originating at a local intensity extreme; identifying a multidimensional edge point corresponding to a maximum edge metric on each said ray; labeling every point on each said ray from said local extreme to said edge point; and labeling an unlabeled point if the unlabeled point is adjacent to a labeled point and the unlabeled paint has a more extreme intensity than the labeled point and the unlabeled point is closer than the labeled point to the local extreme. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for segmenting a small feature in a multidimensional digital array of intensity values in a dataprocessor, the method comprising:
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computing an edge metric along each ray of plurality of multidimensional rays originating at a local intensity extreme; identifying a multidimensional edge point corresponding to a maximum edge metric on each said ray; labeling every point on each said ray from said local extreme to said edge point; labeling an unlabeled point if the unlabeled point is adjacent to a Labeled point and the unlabeled point has a more extreme intensity than the labeled point and the unlabeled point is closer than the labeled point to the local extreme; and additionally labeling an unlabeled point if the unlabeled point is adjacent to a labeled point and has a more extreme intensity than the labeled point and is no farther from the local extreme than the sum of a distance from the labeled point to the local extreme plus an expansive tolerance distance less than the spacing between adjacent points;
whereinan expected size of a small feature is twice an integral number N times a spacing distance between adjacent points in the array, N is greater than 1, the maximum value of the difference in distances between the labeled point and the unlabeled point to the local extreme (Gmax)=−
N+√
{square root over ((N2+2))}, andthe expansive tolerance distance is less than about Gmax.
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19. A data processing apparatus for segmenting a small feature in a multidimensional digital array of intensity values comprising:
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an input for a plurality of intensity values arranged along regular increments in each of a plurality of dimensions; a memory medium for storing the plurality of intensity values as a multidimensional digital array; a processor configured to detect a local intensity extreme in the multidimensional digital array, to identify points along a plurality of rays originating at the total intensity extreme, to identify one edge point on each ray of said plurality of rays, said edge point associated with a maximum edge metric along said ray, to label each point on each ray from the local intensity extreme to the edge point, and to label an unlabeled point adjacent to a labeled point if the unlabeled point has a more extreme intensity than the labeled point and the unlabeled point is closer than the labeled point to the local extreme until no more unlabeled points can be labeled; and an output for providing the labeled points for subsequent processing. - View Dependent Claims (20, 21)
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22. A computer program embodied in a computer readable medium for performing the steps of:
computing an edge metric along each ray of a plurality of multidimensional rays originating at a local intensity extreme, identifying a multidimensional edge point corresponding to a maximum edge metric on each said ray, labeling every point on each said ray from said local extreme to said edge point, and labeling an unlabeled point if the unlabeled point is adjacent to a labeled point and the unlabeled point has a more extreme intensity than the labeled point and the unlabeled point is closer than the labeled point to the local extreme.
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23. A method of labeling points of a multi-dimensional array so as to designate portions of the multi-dimensional array that are associated with an object, the method comprising:
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identifying a first point as belonging to an object due to the first point having an intensity that is a local intensity extreme, wherein the first point is at an interior of the object; determining that a second point that is distanced from the first point has a maximum edge metric, wherein the second point has an intensity that is smaller in magnitude than the intensity of the first point; labeling the second point as an edge point that lies on an edge of the object; determining that a third point that is adjacent to the second point satisfies a predetermined criterion relative to one or more of the first and second points; and labeling the third point as belonging to the object. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A non-transitory computer-readable medium having instructions stored thereon, the instructions comprising:
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instructions for identifying a first point as belonging to an object due to the first point having an intensity that is a local intensity extreme, wherein the first point is at an interior of the object; instructions for determining that a second point that is distanced from the first point has a maximum edge metric, wherein the second point has an intensity that is smaller in magnitude than the intensity of the first point; instructions for labeling the second point as an edge point that lies on an edge of the object; instructions for determining that a third point that is adjacent to the second point satisfies a predetermined criterion relative to one or more of the first and second points; and instructions for labeling the third point as belonging to the object. - View Dependent Claims (38, 39)
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40. A data processing apparatus comprising:
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an input for a plurality of intensity values arranged along regular increments in each of a plurality of dimensions; a memory medium for storing the plurality of intensity values as a multidimensional digital array; and a processor configured to; identify a first point as belonging to an object due to the first point having an intensity that is a local intensity extreme, wherein the first point is at an interior of the object; determine that a second point that is distanced from the first point has a maximum edge metric, wherein the second point has an intensity that is smaller in magnitude than the intensity of the first point; label the second point as an edge point that lies on an edge of the object; determine that a third point that is adjacent to the second point satisfies a predetermined criterion relative to one or more of the first and second points; and label the third point as belonging to the object. - View Dependent Claims (41, 42)
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Specification