SATURATION 85 



of simply adding more white light, we could add some white and sub- 

 tract some colored light, and thus lower the saturation while keeping 

 the total brightness constant. Again, we could reduce the amount of 

 colored light without adding extra white, and thus reduce both satura- 

 tion and brightness. Thus it can be seen that the saturation of a colored 

 light has nothing to do with the particular hue involved, and is also 

 quite independent of the brightness. 



There are two chief ways in which saturation and unsaturation may 

 be manifested. Firstly, saturation can represent the extent to which a 

 spectral color is free from objective adulteration with white light, or the 

 extent to which a pigmentary color is devoid of admixture with white. 

 Unsaturation of a colored light-beam by mixture with a white beam has 

 been mentioned above. A paper- or cloth-color which reflects much light 

 throughout the spectrum in addition to the strong band of wavelengths 

 which gives it its hue, is a 'tint' of that hue — unsaturated by the white 

 it reflects. An artist, mixing Chinese White with an oil color, is un- 

 saturating that color. Likewise, pigmentary colors may be apparently 

 unsaturated by mingling them with black, thus yielding 'shades' of their 

 colors. Admixture with black is really, however, not true unsaturation 

 but is more nearly tantamount to simply reducing intensity and therefore 

 brightness — it is like mixing a light-beam with darkness, which would 

 not unsaturate it even if it could be done! Psychologically, admixture 

 with black is not quite equivalent to reducing intensity, for blackness 

 and darkness are not psychologically identical. Brown, for example, is 

 a black-adulterated color which can be seen as brown only when the 

 conditions are right for seeing black. In a darkroom, a brown area which 

 is not surrounded by lighter areas appears simply as weakly orange or 

 reddish, for the blackness element of the brown becomes mere darkness. 

 If blackness is 'induced' in an orange area by surrounding the latter with 

 white in a darkroom, one can obtain the sensation of brown without 

 resort to pigments, for the orange spot in question need not be pig- 

 mentary — it can be formed by filtered or spectral light. 



It is important, in thinking about saturation, to keep one's attention 

 upon the amount of color, the 'chroma', present — not upon the character 

 of the unsaturating factor present, for this does not matter. It need not 

 even be whiteness which unsaturates, for, if we wish, we may speak of 

 unsaturating a hue with another hue, and thus think of orange as a red 

 unsaturated with yellow; but this is more than a little dangerous since 



