將影像的點素之灰度值加減一個常數，使得整個灰度值分佈圖往左或往右滑動，除了飽和(灰度值為最小或最大)的點素數目有所更動，整個灰度分佈圖的曲線形狀沒有變動。

試合運用於虹膜辨識

-The image of the point addition and subtraction Motonosuke a constant gray value, gray value of the entire distribution to the left or right slide, in addition to saturated (gray value for the minimum or maximum) number of Su-point changes, the entire gray Distribution of the shape of the curve unchanged. All test applied to iris recognition