MEC 325 Lecture Notes - Lecture 5: Color Blindness, Working Memory, Vitreous Body
9 Nov 2016
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Cornea: tough shell for protection, 70%-80% of refractive power. Lens: 20% of refractive power-fine tuning. Retina: fovea center of field of view. Visible range: violet (380 nm) to red (760 nm) Low illumination levels shift perception to green. Design implications: if light is low, objects must be bigger, colour coding won"t work in low light, maintain dark adaptation, red goggles for pilots, red controls for boats, night driving. User characteristics: age (reduced adaptability, poor night vision, disabilities (colour blind, low vision) 20/20 vision is 1/60 degree of arc of resolution text size at 20/60 or 1/3 degree arc min. Tan = (cid:4666)/2(cid:4667: a = character height, d = distance of character from eye. Illuminance (illumination) lux or (lumen/m2: light falling on object. Luminance (candela/m2: reflected light, colour - dark absorbs light, distance light travels before hitting the object. Contrast ratio = (luminance a/luminance b: keep contrast ratio under 10:1, 3:1 is optimal, too much contrast glare.
