SCOTOPIC VISION
The scientific term for human visual perception in low light (night vision). Directed by rod cells in the human eye.

PHOTOPIC VISION
The scientific term for human color vision under normal conditions during the day. Directed by cone cells in the human eye.

MESOPIC VISION
The scientific term for the combination between Photopic and Scotopic vision, taking into account the total sensitivity of the rod cells in the eye for the blue range, with the color perception of the cone cells.

VISUAL CONCLUSION
Extensive research has been conducted to better understand Mesopic vision, and to learn how Scotopic vision stimulates the photoreceptors in the human eye to cause pupil contraction and increased visual acuity.  It was found that Scotopically enhanced light appeared brighter even when light levels were reduced, thus creating the potential to reduce wattage while improving lighting.

The ratio of Scotopic light vs. Photopic light in a lamp is called the S/P ratio. This ratio determines the apparent visual brightness of a light source. Induction lighting produces a high S/P ratio, allowing an 85W induction system to appear as bright or brighter to the human eye than a sodium vapor or metal halide system of twice the wattage.