Means and method of processing optical image edge data
First Claim
1. A method of processing edge data concerning an edge of an image where the edge gradient magnitude Si at a point i in space is approximated by an expression of the form Si=(Xsi2 +Ysi2)1/2, where Xsi and Ysi are the vertical and horizontal edge gradient components for point i lying along mutually orthogonal axes in said space, comprising:
- sensing light from a scene, said scene including an object;
generating electrical signals with said sensed light, said electrical signals representing the intensity of said sensed light with sensed light from said object providing said image;
digitizing said electrical signals;
generating Xsi and Ysi from said digitized electrical signals;
forming the expression AmUi+BmVi wherem is an index and an integer greater than or equal to 1.Am and Bm are constant coefficients to be determined, ##EQU14## determining the values of Am and Bm which minimize the error in the value of Si according to a selected error computation when Si is approximated by AmUi+BmVi;
reforming AmUi+BmVi with said error minimizing values of Am and Bm; and
determining whether or not the ith point is an edge point so that further processing of edge data can proceed.
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Abstract
Means and methods are provided for processing the quantity Si which corresponds to a point i in space where Si=(Xi2 +Yi2)1/2 and Xi and Yi are quantities lying along mutually orthogonal axes in the space. Si is approximated by the expression A|Xi|+B|Yi| where A and B are constant coefficients selected to minimize the error in value of Si according to a selected error computation. A and B can be approximated as a binary power series with each series including a preselected number of terms. Another embodiment does not require means for approximating A and B as binary power series, but segments the coordinate space into m sectors and computes and Am and Bm for each of said m sectors. A particularly advantageous application of the invention is its use in a device and method for processing edge data concerning an edge in an optical image where Si is the Sobel, Prewitt or Roberts square root edge operators.
31 Citations
11 Claims
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1. A method of processing edge data concerning an edge of an image where the edge gradient magnitude Si at a point i in space is approximated by an expression of the form Si=(Xsi2 +Ysi2)1/2, where Xsi and Ysi are the vertical and horizontal edge gradient components for point i lying along mutually orthogonal axes in said space, comprising:
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sensing light from a scene, said scene including an object; generating electrical signals with said sensed light, said electrical signals representing the intensity of said sensed light with sensed light from said object providing said image; digitizing said electrical signals; generating Xsi and Ysi from said digitized electrical signals; forming the expression AmUi+BmVi where m is an index and an integer greater than or equal to 1. Am and Bm are constant coefficients to be determined, ##EQU14## determining the values of Am and Bm which minimize the error in the value of Si according to a selected error computation when Si is approximated by AmUi+BmVi; reforming AmUi+BmVi with said error minimizing values of Am and Bm; and determining whether or not the ith point is an edge point so that further processing of edge data can proceed. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for processing edge data concerning an edge of an optical image where the edge gradient magnitude Si at a point i in space is approximated by an expression of the form Si=(Xsi2 +Ysi2)1/2, where Xsi and Ysi are the vertical and horizontal edge gradient components for point i lying along mutually orthogonal axes in said space, comprising:
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means for sensing light from a scene, said scene including an object; means for generating electrical signals with said sensed light, said electrical signals representing the intensity of said sensed light with sensed light from said object providing said image; means for digitizing said electrical signals; means for generating Xsi and Ysi from said digitized electrical signals; means for forming the expression AmUi+BmVi where m is an index and an integer greater than or equal to Am and Bm are constant coefficients to be determined, ##EQU15## means for determining the values of Am and Bm which minimize the error in the value of Si according to a selected error computation when Si is approximated by AmUi+BmVi; means for reforming AmUi+BmVi with said values of Am and Bm which minimize error; and
means for determining whether or not the ith point is an edge point so that further processing of said edge data can be performed. - View Dependent Claims (8, 9, 10, 11)
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Specification