Perception of color. in 1917, Alfred Munsell created a “notation of colors” based on the human perception of colors (Fig 1). The “tri stimuli” sensitivity of red, green and blue of the eye cones allows humans to live in an additive color space. Munsell showed that any color is defined by three components: 1-Hue, similar to different visible wavelengths. 2-Chromaticity or saturation, similar to concentration of dyes. 3-Value or brightness, representing black and white.

Color Space and Gamut. Three conditions must be met to know the existence of an object, they are 1- An Illuminant (5000°K for photography), 2- An Object (Reflective, Transmissive or Emitting), 3- An Observer (Viewer, monitor, camera, detector). in 1931 La Compagnie Internationale de l’Eclairage, or CIE, met to develop a standard. This resulted in the CIE Color Space defined as a 3D volume of gamut of colors (Fig 2). Different vector notations can be used to define colors: Hue Saturation Lightness or Value (HSL or HSV), RGB (Red Green Blue), Lab (Lightness and two coordinates), and CMYK (Cyan Magenta Yellow Black).