Proceedings PaperA New Restoring Algorithm For The Preferential Enhancement Of Edge Gradients
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We present here a new restoring algorithm that, it is believed, puts edge images on a par with point images with regard to their ability to be enhanced. It is based on use of a "median-window filter." This is a mathematical window of length N, which, when placed on N consecutive image values, replaces the value at its mid-point position by the median of the N intensity values within the window. Used sequentially across an image, the filter tends to completely obliterate oscillations whose period is less than N while simultaneously passing unchanged any monotonically increasing or decreasing image regions (as occur at edges.) This is intrinsically a nonlinear effect. When cyclically used with any linear restoring algorithm, edge-gradient enhancements on the order of 5:1 over that in the image can frequently be obtained, depending on the noise level in the image data. The method is tested on computer-simulated imagery and a photographic image.