LaCie 324 Assembly Instructions

Color Management White Paper 2
Hardware & Human Factors Influence Color Management

Scanner Monitor Proofer Press
Original Print result
1- While this White Paper focuses on monitors and printers, the same issue affects scanners. The range of colors that are distinguishable by a scanner also varies from one model to the next.
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1. HARDWARE/SOFTWARE FACTORS: HOW
RELIABLY CAN PERIPHERALS DISPLAY COLORS?
Basic color reproduction issues can easily be
identified in common computer environments by
comparing the way a given RGB value appears. For
instance, when blue (R:0, G:0, B:255) is displayed
on several computer monitors, the result is often as
many shades of blue as there are available monitors.
There are several reasons for this:
MONITOR TECHNOLOGY DIFFERENCES
While flat panel displays are based on liquid crystal
panels that use color filters to produce color, tube
monitors (also called CRTs) use phosphors instead.
Even among flat panel displays, the differences in
liquid crystal technology types such as IPS, VA and
TN families can cause differences in the way the
same RGB value is displayed.
MONITOR SETTINGS
Luminance, brightness, contrast, and color
temperature differ from one product to another
depending on their usage. The end-user can also
change the factory settings to adjust monitor behavior
to their personal preferences. Both factory and user
settings have a direct influence on monitor colors.
MONITOR AGING
The performance of a monitor varies with its age.
As time goes by, for example, the maximum intensity
of the backlights in a flat panel display can diminish,
thus changing the way that the most saturated colors
appear. Therefore, contrary to common belief, RGB
color representation is not absolute, but essentially
device-dependent.
While graphic artists need to display their work on
monitors when processing documents, they also
need to print or prepare them for printing.
Unfortunately, monitors and printers differ in the
way they produce color.
• Monitors are additive devices that represent colors
by adding red, green, and blue values.
• Printers, on the other hand, are subtractive devices
that rely on reflected light to render colors. Color is
produced by the progressive subtraction of light by
successively applying cyan, magenta, yellow, and
black inks on paper.
The difference in these two processes and
representations of color creates a requirement for a
translation mechanism from the first to the second.
This translation is generally managed, among
others, by software called CMM that is embedded in
the graphic application’s software, operating system
and/or hardware drivers used. Since the CMM is
most often proprietary, the way colors are translated
ultimately depends on which software, OS, and
hardware are used.
In addition to these concerns, a fundamental issue
affecting all color reproduction processes is the
difference in the range of colors that each device
can produce, also called gamut. While it is beyond
the scope of this document to describe mathematical
color representations, a common graphical
In the digital imaging workflow, a document is commonly processed by a series of computer peripherals.
Because these peripherals all differ from one another in the way they display, process, and reproduce
color, discrepancies can appear between the original and the reproduced colors. The issue of reliable
color reproduction is further impacted by human factors. The aim of this document is to explore some of
the key reasons why color reproduction discrepancies appear and to outline some ways through which
they can be minimized.

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representation of gamut relies on a xy-diagram
similar to the one represented in the following graph,
which compares the gamut of common monitors and
printing devices.
In this diagram, the larger ‘horseshoe’ shape
represents the entire range of colors that can be
perceived by the human eye. Additionally, the
gamuts of several devices are represented by the
triangle shapes, which encompass all of the colors
those specific devices can reproduce. As seen in the
diagram above, some colors can easily be displayed
on a computer monitor but not printed, and some
can easily be printed but not displayed on monitors.
This is inherently related to the differences between
ink technology and monitor technology.
While advancements in technology bring hope
to minimize such differences, it is probable that
gamut differences will continue to exist for the
foreseeable future.
In summary, different devices use different types
of technologies and have different gamuts.
Furthermore, the gamut of one device can change as
it gets older, and color reproduction can further vary
as a result of factory and user settings. Rather than
a single “color space” for all peripherals, there is a
range of color spaces, each a little different from the
next—requiring proper translation mechanisms.
As a consequence, a given image (for instance, a
digital photograph) will not necessarily appear
exactly the same on different monitors and printouts.
If these discrepancies are not properly managed,
they may be a source of considerable obstacles in
productivity for digital professionals, resulting in
unnecessary, time-consuming color adjustments
and degradation in document quality rather than
improvements.
2. HUMAN FACTORS: HOW RELIABLY DO OUR
EYES & BRAINS PROCESS COLOR?
People may perceive the same color in completely
different ways. There are several causes for this:
SPECTRAL SENSITIVITY VARIES FROM
PERSON TO PERSON
The way eyes perceive colors can vary according to
the age, condition and mood of the observer.
INFLUENCE OF SURROUNDING COLORS
A blue patch in a red square will look different from
the same patch in a green square.
THE FORMAT AND SIZE OF THE COLOR DISPLAYED
A larger square with the same blue will look brighter
and more powerful than a smaller square.

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VARYING LIGHT SOURCES CAN
ALTER A COLOR’S APPEARANCE
A blue glass jar in daylight, under lamplight, and by
candlelight will produce different color perceptions.
A light source that emits most of its energy in
wavelengths of 570 nm (nanometers) can be
described as emitting mostly “yellow” light. A light
source that has a fl at spectral distribution (equal
energy emitted across the entire spectrum) will be
described as gray.
3. NEED FOR A RELIABLE MANAGEMENT SYSTEM
As explained in this White Paper, there are several
causes for color inaccuracies when processing digital
documents in graphic arts, design and photography.
In order to address these issues, we recommend that
you adhere to the following rules:
• Adapt your working environment to color
management requirements. The ISO 3664 Standard
recommends an ambient light that offers less than
64 lux luminance and has a neutral chroma. Use
neutral lighting; protect your desktop and display
from outside daylight infl uence; change your light
bulbs, turn off your offi ce lamps or reduce their
intensity; shade any windows; etc.
• Build a clearly defi ned color management strategy
and follow standard settings for your calibration
and profi ling: select white point, luminance and
gamma settings according to your needs.
• Rely on measurement tools such as
spectrophotometers and colorimeters rather than
on your eyes with products specifi cally designed
for color management, such as the LaCie blue eye
pro calibrator, integrated in a comprehensive color
management system.
• Calibrate every color sensitive peripheral (printer,
scanner, monitor). In a reliable workfl ow, a color
document must be reproducible by all different
peripherals of the graphic chain with predictable
and consistent results.
• Rely on monitors that can display accurate
colors and are specifi cally designed for color
management, particularly monitors that can be
hardware calibrated such as the LaCie 300 Series.
Future White Papers in this series will explore other aspects of
Color Management in further depth.
“Through a combination of cutting-edge technological
engineering and a rich history of unique design aesthetics,
LaCie continues as a fi rm leader in the color display industry.
Established in the United States, Europe and Japan, LaCie is a
leading worldwide producer of PC and Macintosh compatible
peripherals, including a new generation of color LCD monitors.
By providing top-of-the line tools for multimedia innovation,
LaCie anticipates the needs of creative professionals such as
graphic designers, photographers and fi lmmakers, who require
genuine, practical solutions for accurate color management.”
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