Daniel Suo

Scientific progress goes 'boink'

Ph.D. Candidate
Princeton University
Department of Computer Science

Color

Photon interactions

A photon can interact with a surface in a number of ways:

  • Absorption: the energy from the photon is transformed into the internal energy of the absorber (e.g., thermal energy).
  • Reflection: the energy from the photon changes direction back into the medium form which the photon originated.
  • Diffuse Reflection: an incident ray of light is reflected in many directions, not just one angle.
  • Specular Reflection: an incident ray of light is reflected in one direction (e.g., in mirrors).
  • Transparency: an incident ray of light travels through an interrupting medium unchanged
  • Refraction: an incident ray of light travels through an interrupting medium, but alters direction
  • Fluorescence: an incident ray is absorbed and emitted, often at a different wavelength
  • Subsurface scattering: an incident ray goes into a surface, bounces around one or more times, and comes back out at a different places than the point of entry
  • Phosphorescence: an incident ray is aborbed and emitted at some later time
  • Interreflection: an incident ray strikes reflects some energy, which strikes and illuminates nearby surfaces

Bidirectional reflectance distribution function (BRDF)

  • Lambertian surfaces

  • Specular surfaces

The physics of color

Color mixing

  • Additive mixing

  • Subtractive mixing

The eye and color perception

Color spaces