Oce VarioPrint i Series User Manual

Learn about color differences
What are color differences
When you have printed a specific source color or a spot color, it can be required to check if the
reproduced color is the close enough to the source color. Or, you maybe want to know how
accurate the printer reproduces colors on specific media in general. Therefore, you need to know
how to express and calculate a color difference.
This topic describes several calculation methods and explains how they can be used in color
evaluations.
The comparison of colors always occurs in the same device-independent color space, such as the
CIELAB color space. You literally can draw a line between two colors in a CIELAB color space to
show how close or different they are. Therefore, a color difference is also named the
distance
between colors
. The CIELAB color space represents the colors as we see them. A value that
describes the difference automatically indicates if the difference will likely be visible or not.
The difference between two colors or two groups of colors can be expressed by a color metric.
This topic first describes the CIELAB color spaces and then describes the color metrics that are
derived from them.
CIELAB color values
The CIELAB color space has been developed by the Commission Internationale d'Eclairage (CIE)
and represents a three-dimensional sphere in which every color is unique by its location. The Lab
color value describes the location of the color in the CIELAB color space.
The VarioPrint i-series profiles, color validation tests, spot color libraries, and media family
calibration use the CIELAB color space to define color values and color differences in a device-
independent way.
To read the CIELAB color values of printed colors, you use a spectrophotometer. PRISMAsync
Print Server software can process the measured Lab values into further calculations.
There are two variants of the CIELAB color space: CIE L*a*b* and CIE L*C*h*.
•
The CIE L*a*b* color space is used to describe colors and to make color differences visible.
The CIE L*a*b* color space is based on the fact that the human eye transforms visual
information into three signals: light - dark, red - green, and yellow - blue.
-L
+L
-b
+b
-a
+a
Lab (60, 80, 25)
[312] CIE L*a*b*
The CIE L*a*b* color space components are the following:
•
L* - the lightness component ranges from 0 to 100.
Learn about color differences
250
Chapter 9 - Print what you expect

Oce VarioPrint i Series Specifications

General

Brand	Oce
Model	VarioPrint i Series
Category	Printer
Language	English