Method and camera system for step frame reconnaissance with motion compensation
First Claim
1. A method for imaging a scene with a framing camera comprising a two-dimensional array of photosensitive cells and a stepping mechanism, said array of cells storing pixel information and arranged in a plurality of rows and columns, said columns organized into a plurality of column groups including a first column group and a second column group, comprising, in combination, the sequence of operations of:
- (a) directing with said stepping mechanism adjacent portions of an image of a scene upon said array, said operation of directing performed in a sequence of discrete preselected angular steps, each of said steps separated in time by a predetermined framing interval during which said photosensitive cells of said array are exposed to said image of said scene;
(b) during at least one of said predetermined framing intervals, transferring pixel information in said first column group of said array at a first transfer rate and simultaneously transferring pixel information in said second column group at a second transfer rate different from said first transfer rate, said transferring of pixel information compensating for different rates of image motion in said first and second column groups, respectively, to thereby prevent smearing of an image produced by said array;
(c) during a time period of each of said steps of said stepping mechanism, reading out said pixel information from said array of cells into a data storage or display device; and
(d) repeating operations (a), (b) and (c) in a series of cycles, thereby generating a series of frames of images of said scene with said array of cells.
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Accused Products
Abstract
An electro-optical step-frame camera system in which successive overlapping frames of scene imagery are generated by an electro-optical imaging array, and in which electronic image motion compensation is performed by the array during the generation of at least some of the frames of imagery. The successive frames of imagery are made in a stepping pattern that is repeated in a series of cycles of steps, each step separated by a framing interval in which a frame of imagery is obtained. The stepping cycles of the camera generate sweeping coverage of the terrain of interest. As the velocity to height ratio of the reconnaissance aircraft changes, the stepping cycle and electronic image motion compensation are continually adjusted, so as to ensure maximum scene coverage and preservation of image resolution.
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Citations
22 Claims
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1. A method for imaging a scene with a framing camera comprising a two-dimensional array of photosensitive cells and a stepping mechanism, said array of cells storing pixel information and arranged in a plurality of rows and columns, said columns organized into a plurality of column groups including a first column group and a second column group, comprising, in combination, the sequence of operations of:
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(a) directing with said stepping mechanism adjacent portions of an image of a scene upon said array, said operation of directing performed in a sequence of discrete preselected angular steps, each of said steps separated in time by a predetermined framing interval during which said photosensitive cells of said array are exposed to said image of said scene; (b) during at least one of said predetermined framing intervals, transferring pixel information in said first column group of said array at a first transfer rate and simultaneously transferring pixel information in said second column group at a second transfer rate different from said first transfer rate, said transferring of pixel information compensating for different rates of image motion in said first and second column groups, respectively, to thereby prevent smearing of an image produced by said array; (c) during a time period of each of said steps of said stepping mechanism, reading out said pixel information from said array of cells into a data storage or display device; and (d) repeating operations (a), (b) and (c) in a series of cycles, thereby generating a series of frames of images of said scene with said array of cells. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 22)
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9. An electro-optical step-frame camera system with electronic image motion compensation, comprising, in combination:
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(a) a framing camera comprising a two-dimensional array of photosensitive cells for storing pixel information arranged in rows and columns, said columns arranged in a plurality of column groups including a first column group and a second column group, said array further comprising (i) image motion compensation control means for transferring pixel information in said first column group at a first transfer rate and for transferring pixel information in said second column group at a second transfer rate different from said first transfer rate, said first and second transfer rates corresponding to a rate of image motion in said first and second column groups to thereby prevent smear of an image produced by said array; and (ii) means for reading out pixel information from said array of cells; (b) a lens for focusing an image of a scene upon said array; (c) stepping means for directing said image of said scene upon said lens and said array; (d) means for derotating said image of said scene directed by said stepping means upon said array; (e) drive means for rotating said stepping means in a series of successive cycles, each of said cycles comprising a sequence of discrete preselected angular steps, said sequence of steps directing successive scene images onto said array of cells, said sequence of steps separated in time by a predetermined framing interval during which said array is exposed to an image of said scene; wherein said image motion compensation control circuitry is operative during said predetermined framing intervals to transfer pixel information within said first and second column groups at said first and second different transfer rates, respectively, to thereby prevent smearing of images produced by said array. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification