CS781 - Colour for Computer Graphics - Winter 2009

Lecture 10

Visual Response to Light

Colour matching functions depends on something done by humans,

1. The Eye

2. The Retina

3. Neural Processing

4. Opponent colours theory

Ganglion Cell & Cortical Physiology

Ganglion cells we understand pretty well

  1. Centre-surround organization
    Pretty well every combination
  2. Only colour opponency, no spatial opponency

Cortical cells

Hubel & Weisel (Nobel prize for this), "There is a feedforward network: location -> edges -> motion -> etc."

More recently,

  1. Charlie Michael, "Every cell ever predicted by a psychophysicist has been found in the cortex, and then some."
  2. Peter Lennie, "Thirteen different channels of processing handle colour in one way or another."
  3. Samir Zeki, "I have found cells sensitive to individual wavelengths."

Psychophysical phenomena

How to do experimentation.

  1. Reddish-green and yellowish-blue don't exist
  2. Unique hues
  3. Flicker photometry
  4. Minimally distinct border
  5. Colour naming
  6. Unusual properties of yellow-blue axis

Neural Theories

Other interesting observations

  1. Basic colours
  2. Cardinal colours
  3. Simultaneous contrast

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