Godlove Recipient Presentation
CIE Colorimetry, Past, Present, and Future
Robert W.G. Hunt
Colour Consultant
Salisbury, England
Abstract
The activities of the CIE in colorimetry fall into three main areas: color matching;
color differences; and color appearance.
The introduction in 1931 of the CIE Standard Colorimetric Observer for color matching was
such a historic event that it can be said to mark the beginning of practical colorimetry as
we know it today. Now more than 75 years old, that this Standard Observer is still widely
used is a tribute to the care with which the original experimental work was carried out by
W. David Wright, the 1989 Godlove Award recipient, and John Guild. Their work was combined
with the 1924 V(λ) function, which is in error at wavelengths below 460nm, but the
effects of this are usually considered to be too small to warrant changing the standard. The
CIE 1964 Supplementary Standard Colorimetric Observer, based on matches in a 10° field, was
not combined with the 1924 V(λ) function, but the y10(λ) function involves greater additivity
failures than the V(λ) function, and is therefore a questionable basis for 10° luminance. CIE
Technical Committee are now investigating: the effects of field size and age; discrepancies of
additivity; better prediction of Observer Metamerism; and the provision of daylight type sources.
Colour differences were studied extensively by David L. MacAdam, the 1963 Godlove recipient, and
extensive work on colour difference formulae was carried out by Dorothy Nickerson, the 1961 Godlove
Award recipient. It was in 1976 that the CIE introduced the two color spaces and color difference
formulae, CIELUV and CIELAB. The former has the advantage of incorporating the approximately uniform
chromaticity diagram, u',v'. The latter has since been improved by adding parameters that have
different values in different parts of the space, resulting in the CMC, CIE94, and CIEDE2000 formulae.
Color appearance was first addressed by the CIE by defining, in the 1931 x,y chromaticity diagram,
dominant wavelength, λd , and excitation purity, pe. Then in
1963, the CIE U*V*W* approximately uniform space included an approximately uniform correlate of
lightness, W*. The 1991 Godlove recipient, Richard S. Hunter, introduced his Lab color space and
color-difference meter, which was a forerunner of the 1976 CIELUV and CIELAB approximately uniform
spaces, which included correlates of lightness, L*, hue, huv, hab, chroma,
C*uv, C*ab, and saturation,
suv. Then in 1997 and 2002 the Color Appearance Models CIECAM97s and CIECAM02 were introduced. Future
requirements for Colour Appearance Models include: better prediction of redness-greenness and
yellowness-blueness; prediction of simultaneous contrast; a comprehensive model that includes response
from the rods; a model for unrelated colours; a model for the effects of spatial factors and temporal
factors; a model predicting the effects of gloss and translucency; and a model combining appearance
and colour differences.
Biography
Dr Hunt is well known to ISCC and the color science community. From the 2006 IS&T Color Imagign Conference biography:
Robert Hunt worked for 36 years at the Kodak Research Laboratories in Harrow, England, taking early retirement as Assistant Director of Research in 1982. Since then he has been working as an independent color consultant. He has had two books published: The Reproduction of Colour, now in its sixth edition, and Measuring Colour, now in its third. He has attended all the previous Color Imaging Conferences in Scottsdale and is a regular contributor of keynote papers.
This page last updated 09Mar07.