Method of Non-Uniformity Compensation (NUC) of an Imager
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Abstract
The present invention provides for simple and streamlined boresight correlation of FLIR-to-missile video. Boresight correlation is performed with un-NUCed missile video, which allows boresight correlation and NUC to be performed simultaneously thereby reducing the time required to acquire a target and fire the missile. The current approach uses the motion of the missile seeker for NUCing to produce spatial gradient filtering in the missile image by differencing images as the seeker moves. This compensates DC non-uniformities in the image. A FLIR image is processed with a matching displace and subtract spatial filter constructed based on the tracked scene motion. The FLIR image is resampled to match the missile image resolution, and the two images are preprocessed and correlated using conventional methods. Improved NUC is provided by cross-referencing multiple measurements of each area of the scene as viewed by different pixels in the imager. This approach is based on the simple yet novel premise that every pixel in the array that looks at the same thing should see the same thing. As a result, the NUC terms adapt to non-uniformities in the imager and not the scene.
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Citations
37 Claims
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1. -23. (canceled)
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24. A method of non-uniformity compensation (NUC) of the detection elements of a pixilated imager, comprising:
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registering a temporal sequence of input images from the imager having different fields of view (FOVs) to create a registered average image as an estimate of an input scene; backward mapping the estimated input scene to the different FOVs to create an estimate input image for each input image; comparing each said estimate input image to its associated original input image to estimate pixel-by-pixel response non-uniformity compensation (NUC) terms for the imager; and applying the NUC terms to the images to generate compensated images. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 37)
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34. A method of non-uniformity compensation (NUC) for a pixilated imager, comprising:
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capturing a temporal sequence of input images from the imager having different fields of view (FOVs); compensating each input image with apriori NUC terms if they exist to form compensated images; tracking a FOV motion across the scene; registering and adding the input images together to create a registered sum image; accumulating the number of input images that contribute to each pixel in the scene in a registered count image; dividing the registered sum image by the registered count image to form a registered average image; using the FOV motion to backward map the registered average image to the different FOVs to create an estimated input image for each input image; differencing respective pairs of compensated images and estimated input images to form a sequence of unexplained difference images; performing an Nth order correlation on said unexplained difference images to form NUC error terms; and combining the NUC error terms with the NUC terms from the previous iteration to update the NUC terms. - View Dependent Claims (35)
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36. A method of non-uniformity compensation (NUC) for a pixilated imager, comprising:
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capturing a temporal sequence of input images from the IR imager having different fields of view (FOVs); compensating each input image with apriori NUC terms to form compensated images; tracking a FOV motion across the scene; registering and adding the input images together to create a registered sum image; accumulating the number of input images that contribute to each pixel in the scene in a registered count image; dividing the registered sum image by the registered count image to form a registered average image; convolving the FOV motion against the registered average image to form an ideal stacked average; comparing the ideal stacked average to a stacked average of the compensated images to form a composite unexplained difference image that is output as the NUC error terms to update the NUC terms; correlating said NUC error terms against the FOV motion trace to form a registered sum error; and adding the registered sum error to the registered sum image to update the registered average image for another iteration on the NUC error terms.
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Specification