说明：  将一个图像的颜色信息转移到另一个图像上，在对图像做归一化的时候很有用处
(This approach maps the colour distribution of an over/under stained image to that of a well stained target image. Reinhard presented a method for matching the colour distribution of an image to that of a target image by use of a linear transform in a perceptual colourspace (the lαβ colourspace of Ruderman et al. ) so as to match the means and standard deviations of each colour channel in the two images in that colourspace.)