Using light
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Using Light. The eye curved cornea lens retina fovea optic disk. The Retina has layers of cells. photoreceptors transduce incoming light ganglion cells send signals along to the brain. Two kinds of Photoreceptors. 2 types of photoreceptors: rods and cones

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Presentation Transcript
Using light
Using Light

  • The eye

    • curved cornea

    • lens

    • retina

    • fovea

    • optic disk


The retina has layers of cells
The Retina has layers of cells

  • photoreceptors transduce incoming light

  • ganglion cells send signals along to the brain


Two kinds of photoreceptors
Two kinds of Photoreceptors

  • 2 types of photoreceptors: rods and cones

  • rods are very sensitive - useful in dim light

cones are less sensitive but work even in very bright light


The retina
The Retina

  • Rods and cones are distributed differently across the retina


The retina1
The Retina

  • visual acuity (ability to see detail) depends on cones - thus acuity varies across the visual field


The retina2
The Retina

  • Why don’t you notice your blind spot?


The retina3
The Retina

  • Why don’t you notice your blind spot?

    • Blindspots don’t overlap!

    • Your brain “fills in” the missing information

    • The specific information in the blindspot isn’t much more missing than the rest of the periphery!


The retina4
The Retina

  • three types of cones: short, medium, and long

  • different absorptions enable color vision


Visual pathways
Visual Pathways

  • Ganglion cells project to the brain via the optic nerve

  • information is projected to contralateral cortex!


Seeing depth
Seeing Depth

  • What’s the big problem with seeing depth ?


Seeing depth1
Seeing Depth

  • The world is 3D, the retina is 2D !


Depth cues
Depth Cues

  • Four categories:

    • Pictorial

    • Physiological

    • Motion

    • Stereoscopic


Depth cues1
Depth Cues

  • Pictorial Depth Cues: aspects of 2D images that imply depth


Depth cues2
Depth Cues

  • Pictorial Depth Cues: aspects of 2D images that imply depth

  • Physiological Depth Cues: Proprioception in ocular muscles indicates accommodation and convergence


Depth cues3
Depth Cues

  • Pictorial Depth Cues: aspects of 2D images that imply depth

  • Physiological Depth Cues: Proprioception in ocularmuscles indicates accommodation and convergence

  • Motion Depth Cues: foreground and background move in opposite directions


Depth cues4
Depth Cues

  • Pictorial Depth Cues: aspects of 2D images that imply depth

  • Physiological Depth Cues: Proprioception in ocularmuscles indicates accommodation and convergence

  • Motion Depth Cues: foreground and background move in opposite directions

  • Stereoscopic Depth Cues: disparity between two retinal images indicates distance




Pictorial depth cues2
Pictorial Depth Cues

  • Shadows and Shading


Pictorial depth cues3
Pictorial Depth Cues

  • Shadows and Shading


Pictorial depth cues4
Pictorial Depth Cues

  • Shadows and Shading: visual system assumes light from above


Pictorial depth cues5
Pictorial Depth Cues

  • Shadows and Shading: visual system assumes light from above


Pictorial depth cues6
Pictorial Depth Cues

  • Shadows and Shading


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