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 from lights not marketed as "full-spectrum". Color temperature and Color Rendering Index (CRI) are the standards for measuring light. There is no technical definition of "full-spectrum" so it cannot be measured. To compare "full-spectrum" sources requires direct comparison of spectral distribution. The emission spectrum of a light source varies depending on the light generating mechanism. Thermal sources such as incandescent bulbs produce electromagnetic radiation over a broad and continuous range of wavelengths, including infrared and ultraviolet. A black body radiator is the idealized version of a thermal source. As the temperature of a black body radiator increases, the shape of