Introduction - If you have any usage issues, please Google them yourself
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.