Lightness and Brightness and Other Confusions

Despite colour constancy, determining the exact colour even of nearby objects
in so-called standard or normal conditions becomes a puzzle on closer reflection.
Let us return to the case of the apples in Seeing and Perceiving (p. 36).
Looking at one of the green apples on a white table in neutral daylight, which
part of this round object as viewed from this angle should be considered as
containing the ‘real’ colour of the object? (See also figure 21, p. 98). A naturalist
painter would carefully record the shadows, half-shadows, cast shadows
and highlights. The round object would be translated into either gradients of
greens varying between slightly differing tints, shades and hues or perhaps, in
a more Cézannesque tradition, into a pattern of flat areas of varying greens.
The question is, which of these greens or which point in the continuums of
the gradients represents the ‘local’ colour of the object? One will find several
answers to this question in painting manuals, but very few of them venture to
actually challenge the whole validity of this question.
It is somehow in our nature to treat material objects and surfaces as having,
among all the other permanent properties, the unchanging property of object
colour. Some philosophers will say that there is no such thing as object colour,
that the world is in fact colourless; colours are an illusion and are at the
most ‘projected’ on the world by the subject’s brain or mind. Others say that
colour is a property of, for example, the objects surface, a molecular structure
that lends that surface a propensity to absorb and reflect light according to a
particular profile. In between these two extremes there are various schools of
thought that have attempted either a synthesis of these seemingly irresolvable
theories or have tried to forge a path in completely new directions. Most of
the theories of the third kind could be classified as relational. They emphasize
the relative nature of perceived colour without completely abandoning the
idea of colour as a property of ‘the world outside’.
The question of whether the world is coloured at all in the sense of permanent
properties, is of course a deeply philosophical one. Even more so is the question
of whether we are able to gather any permanent truths about the world
through our senses. 86 Leaving these huge epistemological questions aside, let
us look at the problem of identifying colours from a more pragmatic viewpoint.
It is necessary sometimes to communicate very precise information about the
colour of materials, objects or surfaces. For this purpose various methods and
tools have been developed. First, there is measurement. The sample can be
Thus for exacting colour perception tasks, such as the monitoring of printing jobs, even
the colour temperature of the ambient light is specified in the viewing standard. In
everyday visual tasks a change of up to ±1000 K will have no effect (after adaptation)
on the perceived colours.
For an overview of the ontological and epistemological problems concerning colour
see Arstila 2005; see also Natural Experiences and Physical Abstractions in this volume.
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