Color Perception Quiz

Color Perception

• Additive vs. Subtractive Color Models:
  • Additive model: combining light of different colors to produce a range of colors (e.g., RGB monitors)
  • Subtractive model: absorbing certain wavelengths of light to produce a range of colors (e.g., ink on paper)
• Trichromatic Theory:
  • The human retina has three types of cones sensitive to different ranges of wavelengths:
    • Long-wavelength cones (L-cones): sensitive to red light (~600-700nm)
    • Medium-wavelength cones (M-cones): sensitive to green light (~500-600nm)
    • Short-wavelength cones (S-cones): sensitive to blue light (~400-500nm)
• Color Opponency:
  • The visual system processes colors in an opponent manner:
    • Red-green opponent channel
    • Blue-yellow opponent channel
    • Black-white (achromatic) opponent channel

Retinal Anatomy

• Layers of the Retina:
  1. Photoreceptor layer (rods and cones)
  2. Outer plexiform layer (synapses between photoreceptors and bipolar cells)
  3. Inner nuclear layer (bipolar cells, horizontal cells, and Müller cells)
  4. Inner plexiform layer (synapses between bipolar cells and ganglion cells)
  5. Ganglion cell layer
• Photoreceptors:
  • Rods: sensitive to low light levels, responsible for peripheral and night vision
  • Cones: sensitive to color and high light levels, responsible for central vision
• Retinal Blood Supply:
  • Oxygen and nutrient supply to the retina via the choroid and retinal vessels

Ocular Reflexes

• Pupil Light Reflex:
  • Constriction of the pupil in response to bright light
  • Regulated by the autonomic nervous system
• Accommodation Reflex:
  • Change in lens shape to focus on objects at different distances
  • Regulated by the ciliary muscle and the autonomic nervous system
• Vestibulo-Ocular Reflex:
  • Adjustment of eye movements in response to head movements
  • Regulated by the vestibular system and the oculomotor system

Visual Processing

• Retinogeniculate Pathway:
  • Transmission of visual information from the retina to the lateral geniculate nucleus (LGN)
  • Processing of visual information in the LGN and primary visual cortex (V1)
• Cortical Processing Streams:
  • Ventral pathway (what pathway): object recognition and identification
  • Dorsal pathway (where pathway): spatial relationships and motion detection
• Feature Extraction:
  • Processing of visual information in higher-level visual areas (V2, V3, V4, etc.)
  • Extraction of features such as line orientation, color, and texture

Photoreception

• Phototransduction:
  • Conversion of light into electrical signals in photoreceptors
  • Involves the activation of photopigments (rhodopsin and photopsin) and downstream signaling cascades
• Photopigments:
  • Rhodopsin: sensitive to low light levels, responsible for rod-mediated vision
  • Photopsin: sensitive to higher light levels, responsible for cone-mediated vision
• Signal Amplification:
  • Amplification of the light signal through the phototransduction cascade
  • Involves the activation of second messengers and downstream signaling pathways

Color Perception

• Additive color model combines light of different colors to produce a range of colors, used in RGB monitors.
• Subtractive color model absorbs certain wavelengths of light to produce a range of colors, used in ink on paper.
• Human retina has three types of cones sensitive to different ranges of wavelengths: L-cones (red, 600-700nm), M-cones (green, 500-600nm), and S-cones (blue, 400-500nm).
• Visual system processes colors in an opponent manner: red-green, blue-yellow, and black-white opponent channels.

Retinal Anatomy

• Retina has five layers: photoreceptor layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, and ganglion cell layer.
• Photoreceptors: rods are sensitive to low light levels, responsible for peripheral and night vision; cones are sensitive to color and high light levels, responsible for central vision.
• Retina receives oxygen and nutrient supply via the choroid and retinal vessels.

Ocular Reflexes

• Pupil light reflex: constriction of the pupil in response to bright light, regulated by the autonomic nervous system.
• Accommodation reflex: change in lens shape to focus on objects at different distances, regulated by the ciliary muscle and the autonomic nervous system.
• Vestibulo-ocular reflex: adjustment of eye movements in response to head movements, regulated by the vestibular system and the oculomotor system.

Visual Processing

• Retinogeniculate pathway: transmission of visual information from the retina to the lateral geniculate nucleus (LGN), and processing in the LGN and primary visual cortex (V1).
• Ventral pathway (what pathway): object recognition and identification.
• Dorsal pathway (where pathway): spatial relationships and motion detection.
• Feature extraction: processing of visual information in higher-level visual areas (V2, V3, V4, etc.), extracting features such as line orientation, color, and texture.

Photoreception

• Phototransduction: conversion of light into electrical signals in photoreceptors, involving activation of photopigments (rhodopsin and photopsin) and downstream signaling cascades.
• Photopigments: rhodopsin is sensitive to low light levels, responsible for rod-mediated vision; photopsin is sensitive to higher light levels, responsible for cone-mediated vision.
• Signal amplification: amplification of the light signal through the phototransduction cascade, involving activation of second messengers and downstream signaling pathways.