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 Mark2
and 3
can be obtained by a computer program that is available
for downloading..



