Tracking apparatus and methods using image processing noise reduction
First Claim
1. A method of estimating the position of a target with a tracking system using a sequence of images, comprising:
- acquiring a multi-dimensional image from said tracking system for a time step t;
normalizing said image to produce a normalized image, said normalized image having an intensity within a given range;
super-sampling said normalized image with at least one sample rate to produce a super sampled image;
classifying said normalized image into target and background pixel sets;
determining at least one statistic of said pixel sets, said act of determining at least one statistic comprising;
updating for a plurality of prior time steps a temporal mean and standard deviation from said normalized image;
calculating from said temporal mean and standard deviation;
(i) a target mean and standard deviation of all pixels in said target set, and (ii) a background mean and standard deviation of all pixels in said background set;
scaling the target and background mean standard deviation by a factor; and
setting minimum and maximum bounds on said means and standard deviations;
smoothing a prior probability from a previous time step;
shifting the prior probability to produce an updated prior probability;
calculating a posterior probability using at least said updated prior probability; and
extracting a position of said target for at least one time step using at least said posterior probability.
1 Assignment
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Accused Products
Abstract
Improved apparatus and methodology for image processing and object tracking that, inter alia, reduces noise. In one embodiment, the methodology is applied to moving targets such as missiles in flight, and comprises processing sequences of images that have been corrupted by one or more noise sources (e.g., sensor noise, medium noise, and/or target reflection noise). In this embodiment, a multi-dimensional image is acquired for a first time step t; the acquired image is normalized and sampled, and then segmented into target and background pixel sets. Intensity statistics of the pixel sets are determined, and a prior probability image from a previous time step smoothed. The smoothed prior image is then shifted to produce an updated prior image, and a posterior probability image calculated using the updated prior probability. Finally, the position of the target is extracted using the posterior probability image. A tracking system and controller utilizing this methodology are also disclosed.
142 Citations
30 Claims
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1. A method of estimating the position of a target with a tracking system using a sequence of images, comprising:
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acquiring a multi-dimensional image from said tracking system for a time step t; normalizing said image to produce a normalized image, said normalized image having an intensity within a given range; super-sampling said normalized image with at least one sample rate to produce a super sampled image; classifying said normalized image into target and background pixel sets; determining at least one statistic of said pixel sets, said act of determining at least one statistic comprising; updating for a plurality of prior time steps a temporal mean and standard deviation from said normalized image; calculating from said temporal mean and standard deviation;
(i) a target mean and standard deviation of all pixels in said target set, and (ii) a background mean and standard deviation of all pixels in said background set;scaling the target and background mean standard deviation by a factor; and setting minimum and maximum bounds on said means and standard deviations; smoothing a prior probability from a previous time step; shifting the prior probability to produce an updated prior probability; calculating a posterior probability using at least said updated prior probability; and extracting a position of said target for at least one time step using at least said posterior probability. - View Dependent Claims (2, 3, 4)
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5. A method of estimating the position of a target with a tracking system using a sequence of images, comprising:
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acquiring a multi-dimensional image from said tracking system for a time step t; normalizing said image to produce a normalized image, said normalized image having an intensity within a given range; super-sampling said normalized image with at least one sample rate to produce a super sampled image; classifying said normalized image into target and background pixel sets; determining at least one statistic of said pixel sets; smoothing a prior probability from a previous time step, said act of smoothing comprising; estimating a smoothing parameter by at least; estimating at least one open loop target position fluctuation by taking a difference between (i) a measured control position from a time step prior to t, and (ii) an error signal from a time step prior to t; calculating for time steps up to t at least one target position difference; updating for a plurality of prior time steps a standard deviation from said target position difference; and scaling said standard deviation by a factor; shifting the prior probability to produce an updated prior probability; calculating a posterior probability using at least said updated prior probability; and extracting a position of said target for at least one time step using at least said posterior probability. - View Dependent Claims (6, 7, 8)
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9. A method of estimating the position of a target with a tracking system using a sequence of images, comprising:
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acquiring a multi-dimensional image from said tracking system for a time step t; normalizing said image to produce a normalized image, said normalized image having an intensity within a given range; super-sampling said normalized image with at least one sample rate to produce a super sampled image; classifying said normalized image into target and background pixel sets; determining at least one statistic of said pixel sets; smoothing a prior probability from a previous time step; shifting the prior probability to produce an updated prior probability; calculating a posterior probability using at least said updated prior probability; and extracting a position of said target for at least one time step using at least said posterior probability, said act of extracting a position comprising; smoothing the posterior probability using a smoothing function to produce a smoothed posterior probability; combining said smoothed posterior with said super-sampled image, to produce an intensity-weighted posterior probability; generating an estimate of an initial component of the target position in a first dimension based at least in part on said intensity weighted posterior probability; and generating an estimate of an initial component of the target position in a second dimension based at least in part on said smoothed posterior probability. - View Dependent Claims (10, 11, 12)
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13. A method of estimating the position of a target with a tracking system using a sequence of images, comprising:
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acquiring a multi-dimensional image from said tracking system for a time step t; normalizing said image to produce a normalized image, said normalized image having an intensity within a given range; super-sampling said normalized image with at least one sample rate to produce a super sampled image; classifying said normalized image into target and background pixel sets; determining at least one statistic of said pixel sets; smoothing a prior probability from a previous time step; computing a convolution kernel; shifting the prior probability to produce an updated prior probability using said convolution kernel; calculating a posterior probability using at least said updated prior probability; and extracting a position of said target for at least one time step using at least said posterior probability. - View Dependent Claims (14, 15)
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16. A method of estimating the position of a target with a tracking system using a sequence of images, comprising:
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acquiring a multi-dimensional image from said tracking system for a time step t; normalizing said image to produce a normalized image, said normalized image having an intensity within a given range; super-sampling said normalized image with at least one sample rate to produce a super sampled image; classifying said normalized image into target and background pixel sets; determining at least one statistic of said pixel sets, said act of determining at least one statistic further comprising; updating for a plurality of prior time steps a temporal mean and standard deviation from said normalized image; calculating from said temporal mean and standard deviation;
(i) a target mean and standard deviation of all pixels in said target set, and (ii) a background mean and standard deviation of all pixels in said background set;scaling the target and background mean standard deviation by a factor; and setting minimum and maximum bounds on said means and standard deviations; smoothing a prior probability from a previous time step; shifting the prior probability to produce an updated prior probability; calculating a posterior probability using at least said updated prior probability; and extracting a position of said target for at least one time step using at least said posterior probability. - View Dependent Claims (17, 18, 19, 20)
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21. A method of estimating the position of a target with a tracking system using a sequence of images, comprising:
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acquiring a multi-dimensional image from said tracking system for a time step t; normalizing said image to produce a normalized image, said normalized image having an intensity within a given range; super-sampling said normalized image with at least one sample rate to produce a super sampled image; classifying said normalized image into target and background pixel sets; determining at least one statistic of said pixel sets; smoothing a prior probability from a previous time step, said act of smoothing further comprising estimating a smoothing parameter by at least; estimating at least one open loop target position fluctuation by taking a difference between (i) a measured control position from a time step prior to t, and (ii) an error signal from a time step prior to t; calculating for all time steps up to t at least one target position difference; updating for a plurality of prior time steps a standard deviation from said target position difference; and scaling said standard deviation by a factor; shifting the prior probability to produce an updated prior probability; calculating a posterior probability using at least said updated prior probability; and extracting a position of said target for at least one time step using at least said posterior probability. - View Dependent Claims (22, 23, 24, 25)
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26. A method of estimating the position of a target with a tracking system using a sequence of images, comprising:
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acquiring a multi-dimensional image from said tracking system for a time step t; normalizing said image to produce a normalized image, said normalized image having an intensity within a given range; super-sampling said normalized image with at least one sample rate to produce a super sampled image; classifying said normalized image into target and background pixel sets; determining at least one statistic of said pixel sets; smoothing a prior probability from a previous time step; shifting the prior probability to produce an updated prior probability; calculating a posterior probability using at least said updated prior probability; and extracting a position of said target for at least one time step using at least said posterior probability; wherein said act of extracting a position comprises; smoothing the posterior probability using a smoothing function to produce a smoothed posterior probability; combining said smoothed posterior with said super-sampled image, to produce an intensity-weighted posterior probability; generating an estimate of an initial component of the target position in a first dimension based at least in part on said intensity weighted posterior probability; and generating an estimate of an initial component of the target position in a second dimension based at least in part on said smoothed posterior probability. - View Dependent Claims (27, 28, 29, 30)
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Specification