HP Designjet Z6100 Printer series - Manual (Page 119)

The solution: color management
Many colors from an RGB-controlled device cannot be reproduced in a CMYK-controlled device, and vice
versa. These colors are called “out-of-gamut” colors.
1
. Describe the color behavior of a device as accurately as possible by using an ICC
profile. The color behavior of a device can be described by taking various RGB or CMYK
combinations, sending them to a device, measuring the resulting output, and expressing it in a device-
independent color space (for example, CIE Lab). The resulting relationship is stored in an ICC profile,
which is a standard file that translates the color space of a device(CMYK or RGB) to a device-
independent color space (for example CIE Lab). The process of generating an ICC profile is called
profiling.
2
. Convert colors as effectively as possible by using a Color Management System
(CMS). A CMS is software that uses information from ICC profiles to transform the color space of
one device (defined by a source profile) into the color space of another device (defined by a
destination profile). In this solution, difficulties arise with the colors that exist in the gamut that one
device uses and that the other does not use.
The following four settings describe and CMS:
● CMS: Color Management System. The software that converts the color information that is stored in
the input image (defined by a source profile) into an output image that has the color space specified
by a destination profile. Many different CMSs are on the market: in software programs, in operating
systems, and in printing software, including the HP Designjet Z6100 internal RIP.
● Source profile: a description of the color behavior of the input device
● Destination profile: a description of the color behavior of the output device
● Rendering intent: the most difficult challenge in color management is when a color in the source
gamut does not correspond directly to a color in the destination gamut. When a perfect match is not
possible, choices must be made about how to treat gamut differences. These choices are called
rendering intent. There are four different possibilities depending on the final output that you want to
achieve.
● Use Perceptual for the most pleasing final output. It is suitable for photographic content.
● Use Saturation for vivid final output. It is suitable for business graphics (charts, presentations,
and so on), but is not recommended for color matching.
● Use Relative Colorimetric for press proofing. This rendering intent provides a match for
colors that are inside both the source and destination gamuts, and minimizes differences when
a match is not possible.
● Use Absolute Colorimetric for press proofing (like Relative Colorimetric), when you also
want to simulate the color of the source’s paper.
The solution: color management 107
Color management