Josef Albers' book 
Interaction of Colour (1970) is widely influential. Albers claims that colours react when they are next to another colour. We should never consider the characteristics of a colour as absolute, but always relating to the enviroment. 
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| One page from Interaction of Colour. | 
    Contrast can be defined  as “the difference in visual properties that 
makes an object (or its representation in an image) distinguishable from
 other objects and the background.” In plain English that could be 
described at its most basic level as “things which look different from 
one another”
. (Love of graphics)