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Adaptive updating processor for use in an area correlation video tracker

  • US 4,227,212 A
  • Filed: 09/21/1978
  • Issued: 10/07/1980
  • Est. Priority Date: 09/21/1978
  • Status: Expired due to Term
First Claim
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1. In an area correlation video tracker including an electro-optical sensor which generates frames of video information representative of an intensity pattern of the field of view of said electro-optical sensor corresponding to discrete intervals in time;

  • means for partitioning a preselected portion of said generated video frames into an array of picture elements, the value of each picture element being representative of the gray level intensity corresponding to its index in said array, said array being additionally partitioned into a predetermined number of indexed subarray zones;

    means for acquiring the gray level values of the picture element of a selected first subarray zone corresponding to an acquisition video frame; and

    correlation means for cross-correlating, based on a predetermined metric correlation function, the gray level values of the picture elements of said selected first subarray zone with the picture element gray level values of said partitioned subarray zones of each of a number of video frames generated subsequent said acquisition video frame to identify a second subarray zone of picture elements in each of said number of subsequently generated video frames and to derive a cross-correlation metric value associated with each of said identified second subarray zones, the improvement of an adaptive updating means comprising;

    means operative to perform an autocorrelation of the gray level values of the picture elements of said selected first subarray zone with the gray level value of the picture elements of an at least one predetermined third subarray zone of said acquisition video frame in accordance with said predetermined metric correlation function to derive a reference threshold correlation metric value and to further perform an autocorrelation of the gray level values of the picture elements of said identified second subarray zone with the gray level values of the picture elements of at least one predetermined fourth subarray zone of the same video frame in accordance with said predetermined metric correlation function to derive another threshold correlation metric value, said another threshold correlation metric value being derived for each of said number of subsequently generated video frames;

    means operative to render an update condition based on the results of a comparison between one derived cross-correlation metric value and said reference threshold correlation metric value, said update condition causes the gray level values of the picture elements of said selected first subarray to be replaced with the gray level values of the picture elements of said identified second subarray corresponding to said one cross-correlation metric value and causes said reference threshold correlation metric value to take on the value of said another threshold correlation metric value derived from the video frame corresponding to said one cross-correlation metric value, whereby subsequent cross-correlation processing will be performed with the updated gray level values of the picture elements of the selected first subarray and updated threshold correlation metric value.

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