Night Vision 4+‎

Night Vision is designed to help preserve your scotopic vision (vision under low-light conditions) by reducing the blue and green components of your monitor's output, leaving mostly red, which aids in preserving biological night vision.

Your eyes' photo-receptors consist of rods and cones which are found in the retina, and convert light into electrical signals which are sent to the brain to form an image. Cones create our color vision and are only active in high-light levels. Rods are much more sensitive in low-light conditions, but not to color. Within your rods is the chemical rhodopsin which allows night vision. When exposed to bright light, Rhodopsin bleaches and takes around 5-10 minutes to regenerate. The rhodopsin contained withing the rods is less sensitive to the color red, and this color is often used to help preserve scotopic vision.

Night Vision operates by reducing the gamma values of your computer's three video output channels (R,G,B), particularly the blue and green channels, which allows your monitor to appear dimmer, leaving mostly red. Because it works at a hardware level across your entire screen, the benefits are not limited to only a single application. The effect can be switched on and off at any time, and adjusted to suit the ambient lighting conditions.

Astrophotographers, and video astronomers often resort to placing red cellophane over their computer monitor in an effort to achieve similar results. The Night Vision application performs this function much more easily, and with more adjustability.