Color is a powerful medium for coding, structuring and emphasizing visual information and, as such, used in many computer applications. However, this tool is less effective, or even counterproductive, in the case of people with impaired color vision. This problem can be remedied to a reasonable extent, provided the display designer is able to anticipate the chromatic trouble spots of a particular color palette. For that purpose, a color editor was designed that allows an image to be displayed as if viewed through the eyes of a color-deficient observer. The model used for computing the color transformations, makes use of state-of-the-art knowledge concerning the polymorphism of human cone pigment and the spectral filtering of the eye lens and macular pigment. As a result, the color editor not only enables the emulation of dichromatic color vision, but also of anomalous trichromatism, the more complex, but also more frequently occurring form of deficient color vision (75% of the colorblind population). In addition to its use as a diagnostic design tool, the editor also provides the means for adjusting the color look-up table to the individual needs of a color-deficient display user.