Graphics Programs Reference
In-Depth Information
Sidebar
WYSIWYG:
WYSIWYG is the ideal situation we all hope to achieve: What You See Is What You
Get. However, sometimes What You See Isn't Exactly What You Get! It is important to know
that color management can't (yet) break the laws of physics and as yet, no software product
is shipping with a brain probe (to read your mind). The glowing phosphors of a CRT and a reflec-
tive print can't always match. Under ideal conditions we can produce previews that simulate
the appearance of a reflective print. This may take some creative visualization. For years, pho-
tographers have used Polaroids as an aid to lighting the scene, looking at the Polaroid and then
mentally extrapolating how the transparency would look, based on their experience. For years,
photographers have taken transparency film and made prints, which they accepted as match-
ing the original. Again this was an artistic interpretation based on their years of experience.
Printers and service bureaus have produced proofs and press sheets, which they agreed matched
each other. None of these situations ever produced perfect matches. We understand and except
the limitations of proofing media.
Many conditions affect the match between two different types of media. The environmen-
tal conditions in which we view the background (called the
surround
), that is behind the sub-
jects, and our own vision all play a role. A fun web site that illustrates how our eyes plays tricks
on us can be found at http://www.colorcube.com/illusions/illusion.htm. Color management isn't
perfect and will never produce a perfect matching between disparate media, but it can provide
the best color match based on state of the art color science. The end user must understand the
limitations and consider these when viewing their work.
Calibration versus Profiling
The ICC introduced the idea of cross-platform, open systems for color
management. At the core of this structure are ICC profiles (sometimes
referred to as device profiles). Its important to understand that an ICC
profile is simply a description of how a particular device reproduces color.
The profile achieves this by describing to the color management system
the color space of the device.
Calibration is a process whereby a device is placed into some prede-
termined condition or behavior. An example is when a user calibrates a
display. We want to set some parameters that can be controlled, such as
the display's white point, brightness contrast, and TRC gamma. This cal-
ibration of the device creates a condition that can be standardized and is
repeatable. This allows similar devices in multiple locations to behave the
same way. Since a device such as a display is in a state of flux over time,
it is necessary to calibrate the device. This calibration returns the device
to the original aim point. Calibration is something we need to do on a
regular basis. Particularly with such devices as a display, which varies
considerably over time. In conventional photographic processes, this
would be similar to running control strips and adjusting chemistry to
achieve target densities.
