Radial histogram matching
First Claim
1. A non-transitory storage device including machine instructions that, when executed by a processing resource, cause the processing resource to:
- identify pixels, in a baseline pattern digital image and in an input digital image, that are determined to be on based on a value of a respective pixel meeting a pre-defined threshold criterion;
traverse each of the pixels in the baseline pattern digital image and in the input digital image one time to determine how many of the pixels that are on are contained in each of 360 sectors of a circle, wherein each sector subtends a degree of angle, and wherein the 360 sectors comprise the whole circle;
assign to each of 360 elements of an initial radial histogram, and to each of 360 elements of a target radial histogram, the number of on pixels in that element;
determine a range of the initial radial histogram as a difference between a maximum number of pixels and a minimum number of pixels counted in the 360 elements of the initial radial histogram;
determine a range of the target radial histogram as a difference between a maximum number of pixels and a minimum number of pixels counted in the 360 elements of the target radial histogram;
determine 360 match scores, where each match score is determined by comparing the target radial histogram to a different one of the initial radial histogram and 359 rotated radial histograms, wherein the rotated radial histograms are generated based on the initial radial histogram, and wherein the comparisons take into account a scaling factor based on a ratio of the range of the initial radial histogram and the range of the target radial histogram; and
identify, based on the match scores, an offset rotation between the baseline pattern digital image and the input digital image.
3 Assignments
0 Petitions
Accused Products
Abstract
An example radial histogram matching system may generate a target radial histogram by identifying pixels in an input digital image that are determined to be on, traversing each of the pixels in the input digital image one time to determine how many of the pixels that are turned on are contained in each sector of a circle and assigning to each elements of the target radial histogram the number of on pixels in that element. The system may also compare the target radial histogram to each of an initial and a sequence of rotated radial histograms to determine a match score for each of the comparisons, and identify an offset rotation between a baseline pattern digital image and the input digital image based on the match scores.
36 Citations
15 Claims
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1. A non-transitory storage device including machine instructions that, when executed by a processing resource, cause the processing resource to:
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identify pixels, in a baseline pattern digital image and in an input digital image, that are determined to be on based on a value of a respective pixel meeting a pre-defined threshold criterion; traverse each of the pixels in the baseline pattern digital image and in the input digital image one time to determine how many of the pixels that are on are contained in each of 360 sectors of a circle, wherein each sector subtends a degree of angle, and wherein the 360 sectors comprise the whole circle; assign to each of 360 elements of an initial radial histogram, and to each of 360 elements of a target radial histogram, the number of on pixels in that element; determine a range of the initial radial histogram as a difference between a maximum number of pixels and a minimum number of pixels counted in the 360 elements of the initial radial histogram; determine a range of the target radial histogram as a difference between a maximum number of pixels and a minimum number of pixels counted in the 360 elements of the target radial histogram; determine 360 match scores, where each match score is determined by comparing the target radial histogram to a different one of the initial radial histogram and 359 rotated radial histograms, wherein the rotated radial histograms are generated based on the initial radial histogram, and wherein the comparisons take into account a scaling factor based on a ratio of the range of the initial radial histogram and the range of the target radial histogram; and identify, based on the match scores, an offset rotation between the baseline pattern digital image and the input digital image. - View Dependent Claims (2, 3, 4, 5)
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6. A non-transitory storage device including machine instructions that, when executed by a processing resource, cause the processing resource to:
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identify pixels, in a baseline pattern digital image and in an input digital image, that are determined to be on based on a value of a respective pixel meeting a pre-defined threshold criterion; traverse each of the pixels in the baseline pattern digital image and in the input digital image one time to determine how many of the pixels that are on are contained in each of N of sectors a circle, wherein N>
1, wherein each sector subtends a degree of angle, and wherein the N sectors comprise the whole circle;assign to each of N elements of an initial radial histogram, and to each of N elements of a target radial histogram, the number of on pixels in that element; determine a range of the initial radial histogram as a difference between a maximum number of pixels and a minimum number of pixels counted in the N elements of the initial radial histogram; determine a range of the target radial histogram as a difference between a maximum number of pixels and a minimum number of pixels counted in the N elements of the target radial histogram; determine N match scores, where each match score is determined by comparing the target radial histogram to a different one of the initial radial histogram and N−
1 rotated radial histograms, wherein the rotated radial histograms are generated based on the initial radial histogram, and wherein the comparisons take into account a scaling factor based on a ratio of the range of the initial radial histogram and the range of the target radial histogram; andidentify, based on the match scores, an offset rotation between the baseline pattern digital image and the input digital image. - View Dependent Claims (7, 8, 9, 10)
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11. A system comprising:
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a processing resource; and a non-transitory storage device including machine instructions that, when executed by the processing resource, cause the processing resource to; identify pixels, in a baseline pattern digital image and in an input digital image, that are determined to be on based on a value of a respective pixel meeting a pre-defined threshold criterion; traverse each of the pixels in the baseline pattern digital image and in the input digital image one time to determine how many of the pixels that are on are contained in each of N of sectors a circle, wherein N>
1, wherein each sector subtends a degree of angle, and wherein the N sectors comprise the whole circle;assign to each of N elements of an initial radial histogram, and to each of N elements of a target radial histogram, the number of on pixels in that element; determine a range of the initial radial histogram as a difference between a maximum number of pixels and a minimum number of pixels counted in the N elements of the initial radial histogram; determine a range of the target radial histogram as a difference between a maximum number of pixels and a minimum number of pixels counted in the N elements of the target radial histogram; determine N match scores, where each match score is determined by comparing the target radial histogram to a different one of the initial radial histogram and N−
1 rotated radial histograms, wherein the rotated radial histograms are generated based on the initial radial histogram, and wherein the comparisons take into account a scaling factor based on a ratio of the range of the initial radial histogram and the range of the target radial histogram; andidentify, based on the match scores, an offset rotation between the baseline pattern digital image and the input digital image. - View Dependent Claims (12, 13, 14, 15)
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Specification