Adaptive non-uniformity compensation algorithm
First Claim
1. An adaptive method for removing fixed pattern noise from focal plane array (FPA) imagery, comprising the following steps:
- obtaining respective focused and blurred digitized versions of an FPA image;
applying a set of correction terms to the focused version of said FPA image to provide a corrected, focused FPA image;
applying a filter to the corrected, focused version of said FPA image to obtain a filter focus image;
applying said set of correction terms to said blurred version of the FPA image to provide a corrected, blurred version of said FPA image;
applying said filter to the corrected, blurred image to provide a filter blur image;
calculating fixed pattern noise errors using the filter focus image and the filter blur image; and
employing said fixed pattern noise errors to update the correction terms for use in processing a next FPA image.
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Abstract
An adaptive method for removing fixed pattern noise from focal plane array (FPA) imagery. A set of correction terms is applied to the focused image from the FPA, and a filter is applied to the corrected, focused image. The set of correction terms is also applied to a blurred version of the FPA image, and the filter is applied to the corrected, blurred image. Fixed pattern noise errors are then calculated using the filtered imagery, and employed to update the correction terms. The updated correction terms are then used for processing the next image. In one embodiment, the filter is an anti-median filter. In another embodiment, the filter is an anti-mean filter.
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Citations
16 Claims
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1. An adaptive method for removing fixed pattern noise from focal plane array (FPA) imagery, comprising the following steps:
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obtaining respective focused and blurred digitized versions of an FPA image; applying a set of correction terms to the focused version of said FPA image to provide a corrected, focused FPA image; applying a filter to the corrected, focused version of said FPA image to obtain a filter focus image; applying said set of correction terms to said blurred version of the FPA image to provide a corrected, blurred version of said FPA image; applying said filter to the corrected, blurred image to provide a filter blur image; calculating fixed pattern noise errors using the filter focus image and the filter blur image; and employing said fixed pattern noise errors to update the correction terms for use in processing a next FPA image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An adaptive sensor and non-uniformity compensation system for providing a corrected output image from a focal plane array (FPA), wherein fixed pattern noise has been compensated in FPA imagery, comprising:
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a sensor comprising sensor optics, a focal plane array of infrared detectors for producing FPA images, and analog-to-digital conversion apparatus for converting said FPA images into digitized FPA images comprising a set of pixel values, the sensor optics adapted to provide focused and blurred versions of images; an adaptive non-uniformity compensation processor for compensating for non-uniform sensitivities of said infrared detectors to infrared radiation, said processor adjusting each pixel value to compensate for the differing sensitivity of each detector in the FPA and provide a corrected output image, said processor comprising; first means for applying a set of correction terms to a focused version of said FPA image to provide a corrected, focused FPA image; a first filter system for applying a filter to the corrected, focused version of said FPA image to obtain a filter focus image; second means for applying said set of correction terms to said blurred version of the FPA image to provide a corrected, blurred version of said FPA image; a second filter system for applying said filter to the corrected, blurred image to provide a filter blur image; third means for calculating fixed pattern noise errors using the filter focus image and the filter blur image; and fourth means for employing said fixed pattern noise errors to update the correction terms for use in processing a next FPA image. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification