Proceedings Article | 29 January 2007
KEYWORDS: Light sources and illumination, Computer programming, Colorimetry, Graphic arts, Color management, Calibration, Lamps, Printing, RGB color model, Analytical research
In much the same way that the automobile industry develops new technologies in racing cars and then brings them to a
broader market for commercial and consumer vehicles, CIE Division 8 is trying to spread color management from the
graphic arts market into the broader office and home markets. In both areas, the professional environment is
characterized by highly motivated, highly trained practitioners who see their activity as an end in itself and have access
to expensive technology, state of the art measurement and calibration equipment, and an environment that, if not as
sedate as a research laboratory, is controlled and well-understood. In contrast, the broader market features users who
have relatively little training at the imaging tasks and see them as a means to an end, which is where their real attention
is focused. These users have mass-market equipment and little or no equipment for measurement and calibration. They
use their tools (cars or imaging equipment) in a variety of environments under highly unpredictable conditions. The
challenge to the automobile and imaging engineering communities is to design practical solutions to work in these real
world environments that are less demanding in terms of strict performance, but more demanding in terms of flexibility
and robustness.
In the graphic arts, we have standards that tell us how to perform comparisons between printed images (hardcopy) and
images displayed on a screen (softcopy). The users are told to use sequential binocular comparisons using memory
matching, where they first adapt completely to one viewing condition, study one image, and then adapt to the other
viewing condition and compare the second image against their memory of the first. This provides a nicely controlled
environment where the observer's state of adaptation is easy to calculate. Unfortunately, in the office and home
markets, users insist on comparing the softcopy and hardcopy side by side, and rapidly switching their gaze between
the two images. In such a situation, it is much harder to say what the observer's adaptation is. There are two
phenomena involved. First is mixed chromatic adaptation, where the white point to which the observer is adapted is a
mixture of the white points of the display and the hardcopy. Related to this is what is known as incomplete chromatic
adaptation, where the media white point does not appear perfectly white to the observer. The report from TC8-04
provides equations that extend CIECAM02 to account for mixed and incomplete chromatic adaptation.
Those who work in the graphic arts know that if you want to make critical color judgments, you need a controlled
lighting environment. Most color management systems are designed around a white point of D50, even for displays.
This white point is the default setting for most spectrophotometers, for example. In the office environment, the situation
is much less clear. There are many different lamps used in office lighting with many different white points. There have
been no broad, multi-national studies of office lighting conditions, so we cannot say what typical office lighting is like,
or even if there are any conditions that could be called "typical." TC8-10 is designing such a study. We intend to look
at the spectral power distributions and illumination levels found in areas of offices where people tend to look at images.
Once we have gathered this data, we will analyze it to see if any trends can be found. There may be similarities within
geographic regions, job categories, or seasonal variations that would be useful to know.
CIE Division 8 members hope that by applying the research results from our technical committees, color engineers will
be able to help their customers get pleasing results in the uncalibrated, unmeasured, unpredictable environment that is
the office workplace.
