Evaluating color laser printers 13
Adaptive, accurate halftoning
Adaptive halftoning increases the edge smoothness of text and graphics while maintaining the
quality of filled areas. Adaptive halftoning provides a solution to the requirement for smooth color
and accurate, crisp edges by locating and increasing the digital halftone frequency at edges. The
HP Color LaserJet 5550’s series printer’s engine consistency and reliability combined with smooth
printing allows higher halftone frequencies that produce accurate halftones.
Trapping
To generate a color image, four color planes must be printed: cyan, magenta, yellow, and black.
Trapping is the deliberate overlapping of one color to an adjacent color to reduce the effect of
color plane misregistration.
Included in the trapping component is halo reduction. Halo reduction makes the subordinate colors
recede from the edge of the dominant color. For example, a process black line would be made up
of black, the dominant color, and cyan and magenta, the subordinate colors. The cyan and
magenta near the edge of the black line are reduced or removed. This prevents color from being
seen on the edge of the black line.
Color matching
The process of matching printer output color to your computer screen is quite complex because
printers and computer monitors use different methods of producing color. Monitors display colors
by light pixels using an RGB (red, green, blue) color process, but printers print colors using a
CMYK (cyan, magenta, yellow, and black) process.
Several factors can influence your ability to match printed colors to those on your monitor. These
factors include:
• Print media
• Printer colorants (inks or toners, for example)
• Printing process (inkjet, press, or laser technology, for example)
• Overhead lighting
• Personal differences in perception of color
• Software applications
• Print drivers
• PC operating system
• Monitors
• Video cards and drivers
• Operating environment (humidity, for example)
Keep the above factors in mind when colors on your screen do not perfectly match your printed
colors. For most users, the best method for matching colors on your screen to your printer is to print
sRGB colors.
sRGB
Standard red-green-blue (sRGB) is an industry color standard originally developed by HP and
Microsoft® as a common color language for monitors, input devices (scanners, digital cameras),
and output devices (printers, plotters). It is the default color space used for HP printers, Microsoft
operating systems, the World Wide Web, and most office software sold today. sRGB is
representative of the typical Windows computer monitor today and the convergence standard for
high-definition television.
The latest versions of Adobe® PhotoShop®, CorelDRAW™, Microsoft Office, and many other
applications use sRGB to communicate color. Most importantly, as the default color space in
Microsoft operating systems, sRGB has gained broad adoption as a means to exchange color
information between applications and devices using a common definition that assures typical users
will experience greatly improved color matching. sRGB improves your ability to match colors
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