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
Tactical light high-efficiency white LEDs have led to a wave of brighter and more energy-efficient tactical lights. Tactical lights can be fitted with lenses to produce certain colors, Colored lights or filters provide flexibility for different purposes. Red lights are best for preserving night vision for the law enforcement officer, due to their minimal impact on the rod cells in the eye, while blue light provides high contrast for detecting blood. Light in the infrared spectrum is only visible through night vision devices, allowing the operator to see clearly while reducing the visibility to those not equipped with night vision equipment. Tactical