554 



Simultaneous Colour Contrast. 



2. A certain difference of wave-length is necessary before simultaneous 

 contrast produces any effect. This varies with different colours. 



3. A change of intensity of the light of one colour may make evident 

 a difference which is not perceptible when both colours are of the same 

 luminosity. 



4. Simultaneous contrast may cause the appearance of a colour which is 

 not perceptible without comparison. 



5. Both colours may be affected by simultaneous contrast, each colour 

 appearing as if moved further from the other in the spectral range. 



6. Only one colour may be affected by simultaneous contrast as when 

 a colour of low saturation is compared with white. 



7. When a false estimation of the saturation or hue of a colour has been 

 made the contrast colour is considered in relation to this false estimation. 

 That is to say the missing (or added) colour is deducted from (or added to) 

 both. 



8. A complementary contrast colour does not appear in the absence of 

 objective light of that colour. 



9. The negative after-images of contrasted colours are complementary to 

 the colours seen. 



