将图像按象素进行求反，取得类似照相底片效果。求反处理的图像与原始图“黑白颠倒”， 可以看清原始图中灰黑区域的情况。求反的图像一般用于数字图像的初步处理。-Image pixel negated, to similar photographic film effect. Negates the processed image as the original black and white reversed, you can see the gray area in the original i