Hough transform method for linear ribbon and circular ring detection in the gradient domain
First Claim
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1. A computer-implemented method, comprising:
- converting a portion of an image from a first domain to a second domain to generate a converted portion of the image, wherein the portion of the image comprises a plurality of pixels, wherein each pixel has a value, wherein the converted portion of the image comprises gradient magnitudes corresponding to changes in values for respective pixels in the portion of the image, wherein the plurality of pixels comprises a center pixel;
finding one or more edge pixels in the portion of the image using a weight function applied to a gradient magnitude of the one or more edge pixels, the weight function being based on an angle between a gradient direction of the one or more edge pixels, and a line between the one or more edge pixels and the center pixel;
using each of the one or more edge pixels and the center pixel, calculating a range of radii for each of the one or more edge pixels that contains one or more rings that pass through both the edge pixel and the center pixel;
using the range of radii for each of the one or more edge pixels, voting for each of the one or more edge pixels in a histogram having plurality of bins, wherein each bin of the plurality of bins corresponds to a quantization of radii; and
using the histogram, detecting one or more features in the portion of the image.
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Abstract
A method for converting a portion of an image from a first domain to a second domain. The method may apply a Hough transform on the converted portion of the image, including calculating a range of angles for each tested pixel q relative to a center pixel p, quantizing the range of angles into a plurality of bins, voting each tested pixel q using a range of bins using a weighted voting schema; and detecting one or more features in the portion of the image. The methods may be implemented by program instructions executing in parallel on CPU(s) or GPUs.
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Citations
24 Claims
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1. A computer-implemented method, comprising:
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converting a portion of an image from a first domain to a second domain to generate a converted portion of the image, wherein the portion of the image comprises a plurality of pixels, wherein each pixel has a value, wherein the converted portion of the image comprises gradient magnitudes corresponding to changes in values for respective pixels in the portion of the image, wherein the plurality of pixels comprises a center pixel; finding one or more edge pixels in the portion of the image using a weight function applied to a gradient magnitude of the one or more edge pixels, the weight function being based on an angle between a gradient direction of the one or more edge pixels, and a line between the one or more edge pixels and the center pixel; using each of the one or more edge pixels and the center pixel, calculating a range of radii for each of the one or more edge pixels that contains one or more rings that pass through both the edge pixel and the center pixel; using the range of radii for each of the one or more edge pixels, voting for each of the one or more edge pixels in a histogram having plurality of bins, wherein each bin of the plurality of bins corresponds to a quantization of radii; and using the histogram, detecting one or more features in the portion of the image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system, comprising:
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one or more processors; and a memory coupled to the one or more processors, wherein the memory stores program instructions executable by the one or more processors to perform operations including; converting a portion of an image from a first domain to a second domain to generate a converted portion of the image, wherein the portion of the image comprises a plurality of pixels, wherein each pixel has a value, wherein the converted portion of the image comprises gradient magnitudes corresponding to changes in values for of pixels comprises a center pixel; finding one or more edge pixels in the portion of the image; using each of the one or more edge pixels and the center pixel, calculating a range of radii for each of the one or more edge pixels that contains one or more rings that pass through both the edge pixel and the center pixel; using the range of radii for each of the one or more edge pixels, voting for each of the one or more edge pixels in a histogram having plurality of bins, wherein each bin of the plurality of bins corresponds to a quantization of radii; and using the histogram, detecting one or more features in the portion of the image by; combining votes in the histogram corresponding to a same edge direction to create a merged histogram; and finding candidates for the one or more features based on peaks in the merged histogram. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A computer-readable storage medium storing program instructions executable to implement operations comprising:
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un-warping an image to correct one or more geometric distortions in the image; converting a portion of the image from a first domain to a second domain to generate a converted portion of the image, wherein the portion of the image comprises a plurality of pixels, wherein each pixel has a value, wherein the converted portion of the image comprises gradient magnitudes corresponding to changes in values for respective pixels in the portion of the image, wherein the plurality of pixels comprises a center pixel; finding one or more edge pixels in the portion of the image; using each of the one or more edge pixels and the center pixel, calculating a range of radii for each of the one or more edge pixels that contains one or more rings that pass through both the edge pixel and the center pixel; using the range of radii for each of the one or more edge pixels, voting for each of the one or more edge pixels in a histogram having plurality of bins, wherein each bin of the plurality of bins corresponds to a quantization of radii; and using the histogram, detecting one or more features in the portion of the image. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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Specification