Biology Reference
In-Depth Information
520
540
560
g
500
580
0.5
490
600
480
620
470
650
0
0.5
r
Fig. 2.2 Chromaticity coordinates of monochromatic spectral lights
measured at the central fovea in a dark-adapted state and expressed in
the WDW (i.e. W. D. Wright) diagram. Thus, the data points are plotted in
terms of the matching stimuli 650, 530 and 460 nm and the normalized
units are based on matches of 582.5 and 494 nm. That is, the amount
of the 650 nm and 530 nm stimuli required to match 582.5 nm were
regarded as equal, as were the amounts of 530 nm and 460 nm stimuli
required to match 494 nm.
had a reduced form of colour vision in that the red mechanism was
lacking (Maxwell,
1855
,
1860
,
1872
).
On the basis of his discovery that all spectral lights can
be matched by using only three standard lights, and by using
Grassmann's (
1853
) vector diagram for representation of resultant
colours, Maxwell (
1860
) could present his colour matching results
graphically in a two-dimensional colour space by an equilateral
triangle (the Maxwell colour triangle). (
Fig. 2.2
gives an example of a
modern representation of colours of monochromatic spectral lights
in a two-dimensional colour space.)
The conclusions of Maxwell (
1855
,
1860
) departed from the
colour theory of Newton in two important respects: (1) He made
use of only three primaries, and (2) he found the essential cause of
