At this exhibit, the visitor looks into a set of partially silvered mirrors which combine three color-separated black and white transparencies into one picture. Each transparency was photographed through a red, green, or blue filter. By placing colored (red, green, or blue) filters in front of the three light boxes, the original photo can be recreated in full color. By switching the filters around, all sorts of strangely colored renditions of the original scene can be observed. It turns out that one two-color combination produces fairly good overall color for the image. The intensity of the light in each light box can be controlled from the observer's view point. This exhibit, which we include in the Building Blocks section, illustrates how full color pictures can be composed using only red, green and blue light sources combined. Red, green, and blue are the primary additive colors.