Oki 8c Plus - Manual (Page 11)

Colour Guide 11
English
The problems with using colour
As already explained, a computer monitor, where an image is first
viewed, and a printer which produces the final document use
different methods to generate colours. Indeed they are based
around a different set of primaries (RGB for monitors, CMYK
for printers). Monitors do not generate a full range of perfect
colours and neither do printers. There is a limit on how many
colours a monitor or printer can generate. This is known as a
device’s colour gamut. Some colours can be reproduced by
both devices, while others can be displayed on a monitor but
cannot be printed or vice versa. This in practice may lead to a
colour print not resembling the original on-screen image. So
what has happened?
Images (graphics and text) can be captured through scans or
digital photography, or input directly into the PC via
applications programs. However the original image is
obtained, it will be displayed and manipulated in RGB colour
space (on-screen) and finally converted to CMYK for print.
Each of these processes requires data conversion/
manipulation. An image seen on a computer monitor relies on
the monitor’s ability to reproduce the image and represent
colours within it. Adjustments such as brightness, colour and
contrast also tailor the image to the preference of the viewer
rather than a display of true colour. The data sent to the printer
may not be adjusted to allow for imperfections in the inks used.
Colour management systems
Colour Management Systems (CMS) such as those found in the
OKIPAGE 8c Plus printer driver, allow for any mismatches that
may occur between the RGB and CMYK conversion process.
Colour matching systems go a long way to ensuring a better match
between the input data and printed result but cannot always allow
for monitor adjustment or a variation in paper stock. Paper can
sometimes appear blue or cream in hue which will have an effect
on the light reflected from the page and therefore change the
appearance of some colours. The texture of the paper used will
affect the way that light is scattered and may also result in patches
of light or dense colour. It is therefore best to find and adopt a
paper that provides you with the best results. This of course may
be a process of trial and error, but some recommendations are
given in the User’s Guide.