1.2 Chromatic Light

How to describe color? - We have several possibilities:

1. Make a table of colors, e.g. Munsell color-order system.

**Figure:** A commercial color table
$\includegraphics[]{I-33a}$

2. Assign names to colors, e.g. Light-Goldenrot-Yellow, Medium-Spring-Green, etc.

3. Produce colors by some process: Artists speak about the following variations of pure pigments:

**Figure:** The artists description of colors
$\begin{figure}\begin{picture}(4,4) \put(0.3,3){\makebox(0,0){White}} \put(0.3,2)... ...des}} \put(1,1){\makebox(0,0){$\bullet$}\line(0,2){2}} \end{picture}\end{figure}$

Consequently colored light has following quantities associated:

HUE (corresponding to pure pigment)
SATURATION (i.e. distance from gray of equal intensity)
LIGHTNESS (i.e. perceived intensity of a reflecting object)
or BRIGHTNESS (i.e. perceived intensity of light emitting object).

Andreas Kriegl 2003-07-23