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Using Light

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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Using Light

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  1. Using Light • The eye • curved cornea • lens • retina • fovea • optic disk

  2. The Retina has layers of cells • photoreceptors transduce incoming light • ganglion cells send signals along to the brain

  3. 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

  4. The Retina • Rods and cones are distributed differently across the retina

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

  6. The Retina • Why don’t you notice your blind spot?

  7. 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!

  8. The Retina • three types of cones: short, medium, and long • different absorptions enable color vision

  9. Visual Pathways • Ganglion cells project to the brain via the optic nerve • information is projected to contralateral cortex!

  10. Seeing Depth • What’s the big problem with seeing depth ?

  11. Seeing Depth • The world is 3D, the retina is 2D !

  12. Depth Cues • Four categories: • Pictorial • Physiological • Motion • Stereoscopic

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

  14. Depth Cues • Pictorial Depth Cues: aspects of 2D images that imply depth • Physiological Depth Cues: Proprioception in ocular muscles indicates accommodation and convergence

  15. 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

  16. 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

  17. Pictorial Depth Cues • Occlusion

  18. Pictorial Depth Cues • Occlusion

  19. Pictorial Depth Cues • Shadows and Shading

  20. Pictorial Depth Cues • Shadows and Shading

  21. Pictorial Depth Cues • Shadows and Shading: visual system assumes light from above

  22. Pictorial Depth Cues • Shadows and Shading: visual system assumes light from above

  23. Pictorial Depth Cues • Shadows and Shading

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