Basic Vision
Retina
  • Neurons
  • Contains RODS and CONES
  • Rods = do not see fine details, peripherals
  • Cones = fine details, fovea
Location
  • CONES - fovea
  • RODS -  periphery
Acuity/Motion Sensitivity
  • CONES - high visual acuity
  • RODS - not high, very good at motion sensitivity
Light Sensitivity
  • CONES - Not as light sensitive/need a lot of light
  • RODS - Good in low-light situations
Color Sensitivity
  • CONES - Really good at telling colors apart
  • RODS - Less color sensitive
Dark Adaptation
  • CONES - work before dark environment
  • RODS - work after entering a dark environment
Differential Wavelength Sensitivity
  • CONES - More sensitive
  • RODS - particularly insensitive to redish waves aka red light does not disturb rods
Visual Acuity
  • Ability to see fine details 
  • Measured by visual angle

visual angle (min) = (Lx57.3x60)/D

OR min theta in minutes = 3438H/D

where D = distrance from eye
and L = smallest visual detail needed for identification
Needed functions of: 
  • intrinsic properties of the eye
  • light emitted or received by the target
20/20
with ideal lighting and high contrast, alpha = 1 min with 95% accuracy
Rods
  • High sensitivity to light
  • Poor spatial resolution
  • No color discrimination
  • None in fovea
  • Used for night vision
Cones
  • Color vision
  • Low sensitivity to light
  • High spatial resolution
  • concentrated in fovea
  • very few at periphery
  • daylight vision
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