Tinted trial lenses
The
trial lenses are tinted with one of seven dyes, providing seven colours. There
are 5 trial lenses of each colour (6 in the case of rose and purple). These
trial lenses form a series with increasing degrees of dye deposition. The
deposition increases from one trial lens to the next in the series. Any trial
lens has twice as much pigment as its lighter neighbour in the series, and half
as much pigment as its darker neighbour. The trial lenses can be superimposed
one upon another. Thirty one (2 to the power 5 less
one) combinations of five lenses are possible. These combinations provide 31
small and equal steps of dye deposition ranging from saturation that is so weak
as to be barely noticeable to saturation so strong as to be very dark. The 31
combinations of one colour can be combined with the 31 of a neighbouring colour
so as to provide 961 possible combinations of the two,
with various shades between the two colours. Taking the combinations of pairs
of neighbouring colours in the diagram below is sufficient to fill the gamut
shown in the central CIE UCS diagram. In other words, it is possible to obtain
virtually any colour with a high degree of precision simply by combining trial
lenses of neighbouring colours  e.g. rose and orange, orange and yellow, yellow and green etc. Complementary colours are never
combined, and this ensures that the transmission is as high as possible, given
the colour.
The
combination of trial lenses necessary to match any given setting of the Intuitive
Colorimeter can be obtained by a computer
program that is available for downloading..



