Method and means for recognizing patterns represented in logarithmic polar coordinates
First Claim
1. A method of processing image data to detect the presence of an extended feature or features of interest therein, the method comprising the steps of:
- providing an image represented in a logarithmic polar (log-polar) coordinate system;
selecting image points which are candidates for membership in the feature of interest;
for each selected image point, constructing a curve in the same logarithmic polar coordinate system as the image, the curve characterizing the locus of possible locations of the feature of interest consistent with the selected image point;
accumulating a histogram whose bins coincide with points in the same logarithmic polar coordinate system as the image, which bins contain counts of the number of constructed curves intersecting at the location of the bin; and
selecting bins having greatest counts as representing the locations of definitive points for characterizing the location of the extended feature of interest within the image.
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Abstract
Image processing method and apparatus wherein candidate points are first selected in a log-polar image domain. The points may be selected by edge detection, thresholding, or any method suitable for identifying image points which are likely to lie on some feature of interest. For every candidate point there is drawn, also in the log-polar domain, a mirror image of a curve that represents the log-polar image of a straight line. There is accumulated a log-polar domain histogram of "hits" from the drawing process. Finally, a peak bin is selected. The position of the peak bin corresponds to the position of the recognized line.
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Citations
25 Claims
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1. A method of processing image data to detect the presence of an extended feature or features of interest therein, the method comprising the steps of:
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providing an image represented in a logarithmic polar (log-polar) coordinate system; selecting image points which are candidates for membership in the feature of interest; for each selected image point, constructing a curve in the same logarithmic polar coordinate system as the image, the curve characterizing the locus of possible locations of the feature of interest consistent with the selected image point; accumulating a histogram whose bins coincide with points in the same logarithmic polar coordinate system as the image, which bins contain counts of the number of constructed curves intersecting at the location of the bin; and selecting bins having greatest counts as representing the locations of definitive points for characterizing the location of the extended feature of interest within the image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. Image processing apparatus for detecting the presence of a feature of interest within an image comprising:
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means for providing image data in a log-polar format; means for selecting candidate points within the image data; means for constructing, for every candidate point, a mirror image of the point'"'"'s apical log-line; means, coupled to the means for constructing, for storing values in bins of a histogram; and means for selecting a bin of the histogram having a peak value, the position of the selected bin corresponding to a position of the feature of interest within the image. - View Dependent Claims (16, 17)
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18. A method of processing a set of multi-dimensional data elements so as to detect an extended feature or features of interest, each feature being comprised of a plurality of the multi-dimensional data elements, comprising the steps of:
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providing a representation of the multi-dimensional data elements in a logarithmic-polar coordinate system; selecting multi-dimensional data elements that are candidates for membership in the feature of interest; for each selected multi-dimensional data element, constructing a curve in the same logarithmic-polar coordinate system as that in which the multi-dimensional data element is represented, the curve characterizing a locus of possible locations of the feature of interest, consistent with the selected multi-dimensional data element; accumulating a histogram having bins that coincide with points int the same logarithmic-polar coordinate system as the representation of the multi-dimensional data elements, which bins contain counts of the number of constructed curves intersecting at the location of the bin; and selecting bins having greatest counts as representing parameters that characterize the extended feature or features of interest. - View Dependent Claims (19, 20, 21, 22, 23)
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24. Apparatus for processing a set of multi-dimensional data elements so as to detect an extended feature or features of interest, each feature being comprised of a plurality of the multi-dimensional data elements, comprising:
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means for providing a representation of the multi-dimensional data elements in a logarithmic-polar coordinate system; means for selecting multi-dimensional data elements that are candidates for membership in the feature of interest; means for constructing, for each selected multi-dimensional data element, a curve in the same logarithmic-polar coordinate system as that in which the multi-dimensional data element is represented, the curve being constructed so as to characterize a locus of possible locations of the feature of interest, consistent with the selected multi-dimensional data element; means for accumulating a histogram having bins that coincide with points in the same logarithmic-polar coordinate system as the representation of the multi-dimensional data elements, which bins contain counts of the number of constructed curves intersecting at the location of the bin; and means for selecting bins having greatest counts as representing parameters that characterize the extended feature or features of interest. - View Dependent Claims (25)
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Specification