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Digital background normalizer using two dimensional integration techniques
Digital background normalizer using two dimensional integration techniques
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机译：使用二维积分技术的数字背景归一化器
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摘要
A digital background normalizer system for detecting a point signal or pixel value under test in a background area which is scanned to provide video signal that are converted into digital form. In orderto accumulate by digital integration techniques, the total accumulated signal over a background window is squared by multiplier (20) prior to integrating (22) the volume under a curve which is bounded by the background window area, thereby accumulating the pixels in the complete background window area. Separately, the squared video signal is integrated (24) over a selected smaller central window around the pixel value under test. The accumulated values of the central window are subtracted (28) from the accumulated values of the complete background window to obtain a net accumulated signal value. A mean squared value of the net background accumulated signal (34) is obtained by dividing it by the number of pixels located over such net background window. Next, a root means square (RMS) noise value (38) in the background of the pixel under test is generated from the mean squared value. The RMS value provides the threshold value which is compared with the actual pixel signal under test for detecting if the pixel signal is above the threshold value. The threshold value can thus be continuously changed in accordance with the level of detected background noise.
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