On Vision and Colors are, however, nonessential properties that differ according to the type of light-refracting substance that is used. The top of the upper image is violet. Below the violet is blue. The bottom of the lower image is orange. Above the orange is yellow. In this way, along with the white disk and the black background, four prismatic colors appear: violet, blue, yellow, and orange. This is in disagreement with Newton's claim that there are seven prismatic colors. As the upper image overlaps black, it is seen as violet. Where it overlaps white, it is seen as blue. As the lower image
Full-spectrum light its spectral distribution changes with more energy emitted at shorter (bluer) wavelengths. Sources that rely on fluorescence have a different emission spectrum shape than do thermal sources. Some wavelengths will be produced with greater amplitude than others. Fluorescent sources used for lighting, such as fluorescent lamps, white light emitting diodes, and metal halide lamps are intended to produce light at all wavelengths, but the distribution is different from thermal sources and so colors will appear different under these forms of lighting than under daylight; some colors may match under one light source that don't appear the same under another, a