Bases for the selection of background colors for transparencies

When designers of visual materials want to add color to their black-and-white transparencies, they are concerned about how to select the proper colors. Are there specific colors, transmissions or densities, or brightnesses that provide the best viewing conditions? What background colors will make the message most legible? Solutions to the problems of selecting background colors for projected visuals are related to the effect colors have on visual acuity. This study attempts to answer the question: What background color' should be used on projected materials to meet the legibility needs of the viewer?