The International Color Consortium (ICC) solution for the dilemma
is the introduction of standardized color spaces. These are are
mathematical coordinate systems (three-dimensional representation)
for assigning numerical values to colors. There are many ways to
define such spaces, each with its own benefits and problems. (e.g.
Adobe RGB (1968), sRGB, Pro
Photo RGB). Hence, a color space is a color gamut, which is the
limit for
a set of colors. Adobe RGB, sRGB, and Pro Photo RGB are well-defined
color spaces, which might not match any device in the world. Using
the color space Adobe RGB (this is the one we use) the solution is
the following. The image
internally stores all RGB values in relation to the internal
(abstract) color space (here Adobe RGB). A RGB value in the context
of a color
profile/space actually defines an absolute color. Photoshop's ICC
engine now translates all these color values from the internal space
to the monitor space (using a monitor profile). The same happens
with the printer. Note: A RGB value in the context of a color space
does define an absolute color Repeating this process when receiving
a sent image solves the problem of different monitors not showing
the same color.
Photoshop stores the information about the profile within the image
(TIFF,
JPEG). Avoid applications that do not use or create these embedded
profiles
and also do not support the use of monitor profiles.
The standardized color spaces range from narrow to broad. If your
image is
used with a narrow range then some colors get lost in the
transformation.
Broadening the range to "invent" the missing colors is not possible.
If the
range is very wide, you deal with colors that probably none of your
target
devices will be capable of rendering.
The following list shows some of the most important color spaces:
• sRGB: This space is still narrow but is supported by some
printers. It
might be a good idea to use sRGB for photos on the WEB.
• Adobe RGB (1998): This is a very popular space among Photoshop
users. It covers most printable colors. This is what we use.
• Pro Photo RGB: Color space supported by Kodak (very wide
gamut).
• Apple RGB: Not as wide as Adobe RGB.
Properly displayed color spaces use 3D charts. The industry also
uses some
form of 2D charts to display color spaces.