assigns intensity to each wavelength of light
One theory is that sensitivity to blue is recently evolved.
where is a continuous function of wavelength
C is a three dimensional vector space (colour space)
where L, M, and S are weight functions.
Often add K (blacK) to get better black
Also HSL (double cone)
Also L*u*v and L*a*b
Backwards compatible with black-and-white TV (only show Y)
Readings: Hearn and Baker, Chapter 15, 14-5. Glassner, Volume 1, Chapter 1, 2.