NATS 1870 Lecture 5: Perception 2
21 Jan 2019
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Document Summary
Adjustment to levels of illumination by rods. Low levels of light causes a concentration of rhodopsin. After about 20 minutes, the amount of rhodopsin is at its maximum equilibrium. Small numbers of photons can trigger a signal. Sudden bursts of illumination cause bleaching, which is an overload" message. Momentary blindness occurs as rhodopsin levels reach a new, lower equilibrium. Our ability to discern colour, independent of illumination conditions. This is a subjective feature of the human colour perception system: afterimage. When we look at an image, for example a red spot, the red cones become fatigued form over- activation, decreasing their photopigment molecule concentration, and therefore their sensitivity. So when we look at white, we end up seeing a cyan afterimage as the red cones aren"t receiving whilst the blue and green cones are. This is a great was of finding out which colours are complimentary: simultaneous contrast.
