Colour Perception

Colour Perception

https://en.wikipedia.org/wiki/Color_vision

Physiology

• Light sensitivity
  • Seeing Purple (source: https://www.quora.com/Why-does-purple-light-appear-blue-in-cameras/answer/Bill-Otto-5)
  • Human Eye Quantum Efficiency (see how cones percieve some blue light as red):
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    • Normal Quantum Efficiency:
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      • Canon D450 Quantum Efficiency:
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• Rod and Cone Cells
  • Cone Cells
    • Are three types - Short (S), Medium (M), Long (L)
    • Gives colour vision
    • Most are sensitive to 555 nm (Green)
  • Rod Cells
    • Gives low-light vision at 500 nm

Mathematics

• Physical color is a combination of pure spectral colours (in the visible range)
• Hilbert Space $H_{colour}$ (Infinite Dimensional Vector Space) holds all colours
• Euclidian Spaces
• Each element $C$ of $H_{colour}$ is a function that gives an interval of all the colours $[W_{min},W_{max}]$ to real numbers $w$
• So human percievable colours can be modelled by 3 numbers, to the extend to which each cone cell - S,M,L is stimulated by a wavelength $w$ as $s(w)$, $m(w)$ and $l(w)$.
• This can be thought of as points in a 3-dimensional Euclidian Space, and we call this the ${R^3}_{colour}$