The relationship between a color and the source illuminating it. For more see Color Matters - Design and Art - True Colors and Metamerism and More on Metamerism. For the Lighting Designer, this means that colors must be chosen differently depending on the light source, if the results on stage are to be at all predictable. The noncontinuous nature of discharge and LED sources complicates the use of color. With an RGB LED source, there is only one combination of R-G-B levels to produce a given color. However, with RGBA, RGBW, RGBAW, or 7-color LED sources (such as the Selador fixtures from ETC), there are many setttings of the different colors that produce apparently the same color on a white surface. However, these different metamers of the "same color" produce vastly different color-rendering results on scenery, costumes, and skin. For more, see any of the excellent articles at Mike Wood Consulting.