HP Color LaserJet 4550 printer family - Software Technical Reference

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HP Color LaserJet 4550 Software Technical Reference 220
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3. USING ICC PROFILES AND COLOR MANAGEMENT SYSTEMS (CMS)
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3.1 OVERVIEW OF COLOR MANAGEMENT SYSTEMS (CMS)
Color professionals with more exacting color requirements can use color management systems (software) to
control the color data exchange between devices. Color management is used to convert color data for different
devices with dissimilar color definitions. Color management systems, such as ICM in Windows and ColorSync on
the Macintosh, are available at the operating system level, while others can be integrated into an application.
For most purposes, the sRGB and CMYK Ink emulation paths provide great color on the HP 4550 without any
color management. The HP 4550 is compatible with color management systems when color conversions are
required or desired for more control of the printer color.
A color management system (CMS) performs two main functions:
• Mapping colors between devices with different ranges of color (gamuts), such as scanners and printers.
• Transforming colors from one working space to another, such as from CMYK (cyan/magenta/yellow/black)
to sRGB (a term generally used to define red/green/blue color output for monitors).
When mapping colors from one gamut space to another, the best method often depends on the type of data being
mapped. Some systems provide the option of choosing the method or rendering intent of the color transform. For
example, when transforming photographic data to a smaller data space, it is important to maintain the relative
color differences that give the image a realistic appearance. This process is often called perceptual or image color
mapping. The process of transforming named colors, such as PANTONE®* colors, and matching a standard ink
color as closely as possible, is called a colorimetric transformation. Printing PANTONE®* colors that have been
through a color management system is not as accurate as using the custom calibrated values as described in the
previous section. The other less used option in a color management system is the saturation or graphics intent.
For most practical purposes, the perceptual or image intent will provide the best results.
HP provides CMYK (hp4550c.icm) and sRGB (hp4550r.icm) ICC profiles with its Color LaserJet 4550 printers.
The CMYK profile can only be used with the PS driver while the sRGB profile can be used with any of the HP4550
drivers. The profiles are in the ICM directory of the driver CD-ROM 1 or on the HP Web site. These profiles
describe the way color is interpreted in the default CMYK and RGB modes. The sRGB profile matches the default
RGB mode (sRGB) which is enabled with the Screen Match or Automatic Color Smart II setting in either the PCL
or PS driver. The CMYK profile is based on the default mode which is a SWOP simulation with a CMYK Inkset
setting of FAST in the PS driver. These profiles can be used for color conversions in a color managed workflow.
3.2 CUSTOM ICC PROFILES
Color professionals can also use color management to calibrate specific color devices. This use of color
management requires a custom ICC profile to be built for the specific device. There are many software packages
and measurement devices on the market for this purpose.
To create the best ICC profile for the HP 4550 printer, it should be put in the "Vivid" or full gamut color mode in
the Color Smart II controls. Note that the "Vivid" setting must be set for all object types: text, graphics and
images. An RGB can be built by printing the ICC profile software measurement target with the printer in the Vivid
mode and then keeping the printer in this mode when printing color managed data from the profile.
Note: