New visual detection models developed under the Target Acquisition Model Improvement Program (TAMIP) require characterized color images as an input parameter. These images are used to make predictions of the probability of detection vs time and/or distance for a military target in a background of interest. Techniques to refine the methods of characterizing color images have been ongoing for several years within the Army. The subject of this paper is a method for specifying optimized reflectance standards for characterization of the images. The color of the reflectance standards are selected for compatibility with the outdoor environments used. The need for customization of color reflectance panels is also explained.