Computers, Applications, and Colour (Paul Lyons and Giovanni Moretti)
This tutorial demystifies the theory and practice of colouring computer interfaces.
Sophisticated models of colour integrate physics, the physiology of the eye, perceptual psychology, a
rigorous derivation of the mathematics of colour primaries, and CRT technology. Deprived of this underlying
theory, common colour guidelines seem naive and contradictory.
The tutorial contains a coherent presentation of the important parts of the theory. It explains the basis
for common practical guidelines, and how to prioritise guidelines.
Many colour phenomena aren't explained by spectrum-based and primaries-based models We cover more powerful
mathematical and psychophysical models of colour that turn these phenomena from impenetrable mysteries into
inevitable conclusions - without deriving the mathematics or reviewing a mass of human perceptual
psychology.
In the first section of the tutorial, we cover human colour perception, and outline an unambiguous canonical
colour vocabulary; we explain metamerism, opponent colour theory and colour spaces, including CIE, RGB and
Munsell's. We discuss perceptual uniformity, Macadam's experiments; and shortcomings of common 3D colour
models. We describe CRT primaries and demonstrate the perceptual non-uniformity of conventional
colour-pickers.
In the latter part of the tutorial we translate theory into practical guidelines for application developers.
We cover monitor white points, colour temperature, colour adaptation and monitor calibration, and colour
management systems. We present a number of other miscellaneous pieces of practical colour information,
related to displays on computer monitors.
Although the tutorial is divided into theoretical and practical sections, practical hints and demonstrations
leaven the theoretical section, and theory underpins our recommendations about colour practice.
Intended audience
If you specialise in the physics, technology, or psychology of colour, don't enrol in this tutorial
expecting to learn more about your speciality.
But if you struggle to design interfaces that work visually; if you want a deeper understanding of colour in
general and greater confidence in choosing colour combinations, then this is the tutorial for you. We've
assembled an explanation of various colour models and technologies that will inform your colour decisions.
We aren't physicists, experts on colour theory, or psychologists; we are computer scientists who experienced
firsthand the difficulty of choosing colours for applications. We are also undertaking research into a
practical application of a mathematical model for facilitating colour choice. Dissatified with the
guidelines in HCI texts, we turned to colour theory, looking for a few simple principles to help us.
Instead, we found a plethora of complex principles, which we have boiled down to a knowledge base that we
have shared with other practitioners around the world, via tutorials like this one.
Outcomes for attendees
You'll learn why physics only explains part of the phenomenon of colour, how the
eye distinguishes colours, and a little of the psychology of colour perception. And when to abandon all of
those and think in terms of monitor technology.
You'll also get a fistful of practical hints that will increase your chances of producing colour interfaces
that work - both aesthetically, and functionally.
Specifically, you'll learn about
- Standard colour vocabulary and common colour models
- Additive and subtractive colour mixing
- Primaries
- White points
- A psychological, perceptual perspective on colour
- Calibration of colour equipment (gamma)
- Colour harmony
- Colour management systems (CMSs)
- Commercially important colour spaces
- Device gamut and its implications
- Colouring for text
Schedule
The tutorial is divided into two halves. In the first half, Paul presents foundation material,
covering colour models, and with a few practical hints thrown in. After a break for coffee, Giovanni gets
down to the nitty gritty, with practical aspects like monitor gamma, printing, colour management systems,
and ways of choosing sets of colours that "go together".
Other material
You'll also receive a CD containing software (free for non-commercial applications) for
colour space conversions, and for generating colour schemes based around perceptually uniform colour spaces.
