This paper presents a technique to choose appropriate light source for maximizing the contrast between the object and the background surfaces in color vision application. From the physics of color image formation, three parameters which affect generating signal of color digital camera are researched. An optimal color illumination for enhancing color contrast can be found by maximizing these surfaces spectral reflectance. The discrimination of these surfaces spectral reflectance was estimated by using average color difference in CIELab color space. A printed color patch which have seven several colored characters was used to demonstrate the approach. For each colored character, appropriate Light Emitting Diode (LED) illumination was selected to maximize the discriminability, which is more suitable than D65 illumination. These experiments illustrate the usefulness of properly chosen color illumination in color vision application.