Detail preserving reproduction of color images for monochromats and dichromats

In spite of the ever-increasing prevalence of low-cost, color printing devices, gray-scale printers remain in widespread use. Authors producing documents with color images for any venue must account for the possibility that the color images might be reduced to gray scale before they are viewed. Because conversion to gray scale reduces the number of color dimensions, some loss of visual information is generally unavoidable. Ideally, we can restrict this loss to features that vary minimally within the color image. Nevertheless, with standard procedures in widespread use, this objective is not often achieved, and important image detail is often lost. Consequently, algorithms that convert color images to gray scale in a way that preserves information remain important. Human observers with color-deficient vision may experience the same problem, in that they may perceive distinct colors to be indistinguishable and thus lose image detail. The same strategy that is used in converting color images to gray scale provides a method for recoloring the images to deliver increased information content to such observers.