<P> A dark area has limited light sources, making things hard to see . Exposure to alternating light and darkness (night and day) has caused several evolutionary adaptations to darkness . When a vertebrate, like a human, enters a dark area, its pupils dilate, allowing more light to enter the eye and improving night vision . Also, the light detecting cells in the human eye (rods and cones) will regenerate more unbleached rhodopsin when adapting to darkness . </P> <P> One scientific measure of darkness is the Bortle Dark - Sky Scale, which indicates the night sky's and stars' brightness at a particular location, and the observability of celestial objects at that location . (See also: Sky brightness) </P> <P> The color of a point, on a standard 24 - bit computer display, is defined by three RGB (red, green, blue) values, each ranging from 0 - 255 . When the red, green, and blue components of a pixel are fully illuminated (255,255,255), the pixel appears white; when all three components are unilluminated (0, 0, 0), the pixel appears black . </P> <Table> <Tr> <Td> </Td> <Td> hide This section has multiple issues . Please help improve it or discuss these issues on the talk page . (Learn how and when to remove these template messages) <Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (January 2010) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Table> <Tr> <Td> </Td> <Td> This section possibly contains original research . Please improve it by verifying the claims made and adding inline citations . Statements consisting only of original research should be removed . (November 2014) (Learn how and when to remove this template message) </Td> </Tr> </Table> (Learn how and when to remove this template message) </Td> </Tr> </Table>

Who said darkness is the absence of light