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The SPECTRAL SENSITIVITY of the eyes for white light 
; is a property the eye has in common with panchromatic 
Physiological photographic emulsions, or better the other way 
Aspects around — the emulsion was made later, 
However, yellow is perceived as being brighter, but 
this is almost colour perception - an item which will 
be trated in paragraph 4. Instruments for subjective 
use, such as binoculars, are colour-corrected for green, whereas odd 
lenses are optimized for blue-green, and should not be used as magni- 
fying glasses or the like. 
COLOUR SENSITIVITY is a different property. Similar to a three-layer 
colour-film, the central part of the retina is colour-film, the central 
part of the retina is covered with a mosaic of 3 different sensitive 
receptors: red-green-blue, with considerable overlap, the red even has 
a secondary peak in the blue. Paradoxically, this only recently proven 
fact (the spectral absorptance of the active chemicals is known since 
1964, MacNichol; Boynton 1967) is familiar to almost everybody, in big 
contrast to properties like imaging quality and eye movements, 
This three fold sensitivity imposes important restrictions on 
multi-spectral photography. Did you ever realize that KODAK need not 
manufacture & 5 layer colour film? Our eyes would see no more on it than 
on an ordinary 3 layer print. Also: photo-interpretors can at most work 
with 3 images at a time, namely 3 transparencies projected in register 
in the three basic colours: blue-yellow-red (Colwell 1968). 
  
alg 
a differential colour sennitivity alter Smith 1946 b.109 
3 ser also Naumann 1960 p. 120. 
2 Over a range ol 300 nm (Alue to deep red) 
J x on the average a shift ed 3 "m can be seen. 
4 773867779 77 m 
[A resultant property is the differential colour discrimination of 
pure spectral colours (the rainbow spectrum): a normal person can 
distinguish more than 100 colours throughout the spectral range, the 
best distinction occurs in the blue-green region and in the orange-red 
transition-range. Notice that only some ten colours can be remembered. 
However, this colour "perception" where "Language" comes into, will 
be treated under psychology. 
A highly significant deviation is the large number of male persons 
(5 to 10%) who have a deficiency in their colour vision - that is in 
their spectral sensitivity as far as the 3 types of retinal rods is 
concerned, or of the chemicals, or of the nerve connections. Female 
operators are at least a thousand times better fit for colour-photo 
interpretation, (Naumann, 1960 quotes on page 119 that 25% male and 
0.1L, female are with colour deficiencies).