OKI C7000, C9000 User Guide

OKI C7000 Series and OKI C9000 Series

Colour Guide

Preface

EEC compatibility

Every effort has been made to ensure that the
information in this document is complete, accurate, and
up-to-date. Oki assumes no responsibility for the results
of errors beyond its control. Oki also cannot guarantee
that changes in software and equipment made by other
manufacturers and referred to in this guide will not
affect the applicability of the information in it. Mention
of software products manufactured by other companies
does not necessarily constitute endorsement by Oki.

Copyright 2000 by Oki. All rights reserved.

Oki is a registered trademark of Oki Electric Industry
Company Ltd.

Energy Star is a trademark of the United States
Environmental Protection Agency.

Microsoft, MS-DOS and Windows are registered
trademarks of Microsoft Corporation.

This product complies with the
requirements of the Council
Directives 89/336/EEC (EMC) and
73/23/EEC (LVD), as amended
where applicable, on the
approximation of the laws of the
member states relating to
Electromagnetic Compatibility and
Low Voltage.

Energy Star

As an Energy Star Partner, Oki
has determined that this product
meets the Energy Star guidelines
for energy efficiency.

Universal Serial Bus

This printer is fitted with an
industry standard universal
serial bus (USB) data interface.

ii Colour Guide

Table of contents

English

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

EEC compatibility. . . . . . . . . . . . . . . . . . . . . . . . . . ii

Energy Star . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Universal Serial Bus . . . . . . . . . . . . . . . . . . . . . . . . ii

Table of contents. . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Colour Printing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Use of colour. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Colour perception . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Electromagnetic spectrum. . . . . . . . . . . . . . . . . . . . .5

Primary and secondary colours. . . . . . . . . . . . . . . . .6

Additive and subtractive primaries . . . . . . . . . . . . . .7

Additive primaries. . . . . . . . . . . . . . . . . . . . . . . .7

Subtractive primaries . . . . . . . . . . . . . . . . . . . . .8

Neutral colours . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Colour complements. . . . . . . . . . . . . . . . . . . . . . . .10

Colour wheel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Problems using colour . . . . . . . . . . . . . . . . . . . . . .12

Colour management systems . . . . . . . . . . . . . . . . .13

Specifying colour . . . . . . . . . . . . . . . . . . . . . . . . . .14

Printing colour . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Colour registration . . . . . . . . . . . . . . . . . . . . . . . . .17

Colour adjustments . . . . . . . . . . . . . . . . . . . . . . . . .18

OKI C7000/C9000 Printer Drivers . . . . . . . . . . . . . 19

Colour management. . . . . . . . . . . . . . . . . . . . . . . . 20

Windows and Macintosh PostScript driver . . . . . . 21

Windows colour matching . . . . . . . . . . . . . . . . 21

Image colour matching. . . . . . . . . . . . . . . . 21

Black finish. . . . . . . . . . . . . . . . . . . . . . . . . 21

Colour halftone. . . . . . . . . . . . . . . . . . . . . . 22

Image colour rendering style . . . . . . . . . . . 22

Macintosh colour matching . . . . . . . . . . . . . . . 22

Colour/greyscale. . . . . . . . . . . . . . . . . . . . . 22

Black and white . . . . . . . . . . . . . . . . . . . . . 22

ColorSync colour matching . . . . . . . . . . . . 23

PostScript colour matching. . . . . . . . . . . . . 23

Windows ICM . . . . . . . . . . . . . . . . . . . . . . . . . 23

No colour matching . . . . . . . . . . . . . . . . . . . . . 24

Print in greyscale . . . . . . . . . . . . . . . . . . . . . . . 24

Print colour separations . . . . . . . . . . . . . . . . . . 24

Windows PCL driver . . . . . . . . . . . . . . . . . . . . . . . 25

Auto colour. . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Manual colour . . . . . . . . . . . . . . . . . . . . . . . . . 25

Halftone type . . . . . . . . . . . . . . . . . . . . . . . 25

Colour setting . . . . . . . . . . . . . . . . . . . . . . . 26

Manual adjustment . . . . . . . . . . . . . . . . . . . 26

Print colour swatch . . . . . . . . . . . . . . . . . . . 26

Preface iii

Monochrome . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Black finishing in photo printing . . . . . . . . 27

Monochrome dithering . . . . . . . . . . . . . . . . 27

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

iv Colour Guide

Colour Printing

Introduction

This Colour Guide has been conceived to provide you
with a broad overview of issues related to colour
printing, in order that the best use of colour be made in
the software applications used. The text is designed to
describe the technical issues in a manner that can be
understood by anyone involved in the preparation of
colour documents.

Please familiarise yourself with the user documentation
provided, which describes operational details of the
OKI printer setup and configuration for specific
options.

OKI are sure that you will find this colour printer an
excellent part of printing solution. If you have any
comments with regard to the content of this document,
then please let us know through your local OKI
representative.

English

Colour Printing 1

Use of colour

Recent advances have brought colour to the desktop in
a way that could not have been imagined a decade ago.
It has been shown that using colour in print can increase
memory retention by up to 65% and readership by as
much as 40%, not to mention the added impact that it
provides. As colour becomes more and more accessible
it is essential to understand the importance of colour
and how best to use it.

People use colour for different reasons; it has become a
very important tool and is used widely in marketing to
grab attention and communicate ideas and, when used
effectively, can alter the viewer’s perception.

Colour can be used in text documents as well as for
graphics. It can be used to emphasise headings or
particular words which would otherwise be lost in the
vast array of black and white. Colour adds impetus to a
company logo and can be as important as the design
itself. The use of colour also makes a document easier
to comprehend and can convey information at a glance.
For example, using red to highlight negative figures in
a spreadsheet.

The use of colour should be considered an integral part
of any presentation or document and not added at the
end as an afterthought.

2 Colour Guide

The following examples list some widely used colours
and their significance:

This is a very powerful and passionate colour.
The power and passion it portrays has made it
a favourite for many exotic sports cars.

Unlike red, green is a very calming and
‘natural’ colour. It signifies trees, grass and
plant life in general. It is soothing and perhaps
associated with a stroll in a field. As well as
the calming side of green, it is also the colour
of envy.

A cool and refreshing colour. It is the colour of
summer skies and a clear blue sea which
produces a calming effect. Dark blues are
associated with wealth and dignity and also
have names that suggest these virtues – Royal
blue, Navy blue, etc.

This is really an absence of colour and the
contrast that it provides with other colours has
made it one of the most widely used. Black is
usually associated with night and darkness

English

The colour of pure snow and in itself suggests
purity. It is used in hospitals to portray an air
of cleanliness and sterility. Like black, white
can be paired with most colours and is
therefore very popular.

In short, colours can be used effectively to send their
own message, regardless of the message that they are
supporting. The colours used within a message are seen
and automatically decoded before the message itself
has been read. This underlines the importance and

effectiveness of using colour.

Colour Printing 3

Colour perception

Colour does not exist by itself but is dependent on the
presence of:

• a light source

• an object

•an observer

Our perception of colour involves light from a source
being reflected off, or transmitted through, an object
and entering the eye.

Light interacts with an object and what we see is the
final result of that interaction. An object can reflect,
transmit or emit light. A reflective object absorbs some
sections of the visible spectrum and reflects the rest.
What we see is the reflected portion. An object
removing wavelengths at the ultra violet end for
example, will appear red in hue. A transmissive object
allows light to pass through it and may absorb a section.
The colour of the object in this case will depend upon
the wavelengths of light that are allowed to pass
through. An emissive object emits light and the
appearance of the light will depend on the wavelengths
emitted. In short, the composition of the light and its
interaction with the object will define the colour we see.

4 Colour Guide

1 micrometre= 1×10-6 metre

(0·001 mm)

1 nanometre= 1×10

-9

metre

(0·000001 mm)

1 picometre= 1×10

-12

metre

(0·000000001 mm)

1 femtometre= 1×10

-15

metre

(0·000000000001 mm)

Visible light spectrum

Electromagnetic spectrum

All colours we can see fall into what is the visible part
of the electromagnetic (EM) spectrum. The visible
portion of the EM spectrum is minute and although we
are ‘blind’ to the rest, the part we can see has a
significant effect on our perception of everything
around us.

If light containing all visible wavelengths in balanced
quantities is detected, then white light is seen. If there
is an absence of all wavelengths then black is
perceived. The infinite combination of different
wavelengths give rise to what we perceive as colour. So
colour is light.

When our eyes receive information containing a strong
content of a particular wavelength then we interpret that
as a colour. A strong content around 700 nm (0.0007
mm wavelength) is interpreted as red and at the other
end of the scale, 400 nm is interpreted as violet.

Visible light spectrum

English

Colour Printing 5

Primary and secondary colours

In theory, all colours can be made up from a very small
group of ‘colour elements’. There are three primary
colours, and all other colours can, in theory, be obtained
by mixing the primary colours in varying proportions.
Mixing two primary colours in equal proportions
produces what is known as a secondary colour.

PROCESS

DISPLAY

6 Colour Guide

Additive and subtractive

standard dot display Trinitron™ display

primaries

Primary colours can be split into two categories which
are termed additive and subtractive. It is important to
note the difference between mixing additive primaries
and subtractive primaries. For example mixing red and
green inks will produce a ‘muddy’ brown, whilst red
and green light mixes to give yellow. So in which way
do the two models differ ?

GREEN YELLOW

CYAN

English

Additive primaries

Video technology such as computer monitors and
television screens use the additive model. The additive
primaries are Red, Green and Blue (RGB). Starting
from black (lack of colour) and adding red, green and
blue in equal quantities will generate shades of grey
with white being generated with full, balanced
intensities of all three. Mixing the three colours in
different quantities will generate intermediate colours.

RED

BLUE MAGENTA

Colour Printing 7

Subtractive primaries

Cyan, Magenta and Yellow (CMY) are known as the
subtractive primaries and are commonly used in
printing processes. In this case we start with a white
background (usually paper) and add translucent inks of
cyan, magenta and yellow to subtract certain
wavelengths of light. For example, cyan ink on a page
appears to be this colour because the ink removes
components of red light and reflects green and blue,
which we perceive as cyan.

In theory, a combination of the three subtractive
primaries will produce black. In practice however,
pigments used in inks are not perfect and usually give
rise to a dark green/brown. For this reason, in many
colour output devices, a separate black ink is used to
produce greys and black (in shadows and black text for
example). This is the CMYK model and is the method
most widely used in the colour printing and printer
industry. The OKI C7000 Series and OKI C9000 Series
of printers use separate cartridges of cyan, magenta,
yellow and black toner to generate high definition
colour images for the workgroup or networked
environment.

Traditional CMYK print

8 Colour Guide