Luminance =
physical measure
Brightness =
perceived amount of light
Eye sensitive over 9 orders or
magnitude
–5
orders of magnitude (room – sunlight)
–Receptors
bleach and less sensitive with more light
–Takes
up to half an hour to recover sensitivity
Eye is NOT a light meter
–Designed to detect CHANGES
–Not good for detecting Absolute Values
–Extremely sensitive to Differences & Changes