Colors

#comp37111

• Colour for the observer = Illuminance x Reflectance.
• 3 Primary colours: Red, Green and Blue.
• Our eyes have 3 cones: L, M and S.
• Coloured light are additive because they "sum up their wavelengths" when overlapping with each other
• Chemical pigments and ink are subtractive colours

• Intensity: Absolute brightness, unit candela per square metre. AUC of Energy x Wavelength. More AUC => More Amount of that wavelength
• Hue: Predominant wavelength that defines the colour. Mean of the graph (Energy x wavelength).
• Saturation/Chroma: Amount of achromatic light = Variance from the mean. (how close it is to white)

Colour Space

• Standard Colour Space: CIE XYZ
  • The 3 values for each wavelength (RGB) are known as tri-stimulus values.
• Some values in the Red wavelength can't be perceived (negative wavelength) so we simply modify them by adding respective green and blue counterparts.

Chromaticity Chart

• 2D projection of 3D colours $$x = X / (Z+ Y+ Z), y = Y /(X+Y+Z)$$
• The realisable chromaticity is always a triangle in the XY chromaticity chromaticity diagram because we can only add lights together and there are no negative lights.