Lightness and Brightness and Other Confusions

What to do?
In the light of the complexity of human experience it could seem almost impossible
to find a common language to communicate about the human perception
of colour and light in a spatial context. Our experience is not without
structure or laws and certainly there are many concepts describing human
experience. You could even say that there are too many – and disparate –
concepts to be useful in communication. The basic problem, however, is not
the great number of concepts but the fact that they often lack a distinct position
in a coherent and well-defined structure of concepts. Without a comprehensive
structure of content it is not possible to see how different concepts
are related to each other or in what respect they refer to different aspects of
reality.
Physical abstractions
The concepts referring to abstract properties and hidden, underlying, but
measurable structures of the physical world are useful as long as they are
used to describe the material world. It is necessary for paint industries and
light source industries to have the use of instruments to control and maintain
physical standards of their products. But in the field of colour and light,
visual/perceptual phenomena are too often described and analysed with the
use of physically based concepts, which can give the false impression that
physical measurements also measure what we see. This is not only a question
of simplification. Using physically based concepts to describe perception of
colour and light may be both misleading and incorrect. It is, however, no
surprise that it happens all the time. In the technical world of light sources,
projectors and spotlights there are very few words relating to human experience
of light; physically or technically based concepts are used instead. We
find the same tendency in art, where painters often use names of pigments to
describe hues or colour nuances. 30
Natural experiences
Apart from the scientific colour systems, which are partially or totally based
on the visual perception of colour (for example the Natural Colour System,
the Munsell Colour Notation System or the OSA Uniform Color Space 31 ),
there is no general conceptual standard for the human experience of colour.
The aim of the perceptual colour systems is to offer standards for colour dis-
30 Today pigment names for artists’ paints rarely even refer to the genuine pigment,
which adds to the confusion.
31 The OSA-UCS is a colour space first published in 1974 and developed by the Optical
Society of America’s Committee on Uniform Color Scales.
29