| UNDERSTANDING
RGB AND CMYK
What
is the difference and how does this affect you?
Well, scanners and digital
cameras create images using combinations of just three colours:
Red, Green and Blue (called "RGB"). These are
the primary colours of light, which computers use
to display images on your screen.
Printing presses print full
colour pictures using a different set of colours, the primary
colours of pigment: Cyan (blue), Magenta (red), Yellow
and Black (called "CMYK"). This is "4-colour
process" or "full-colour" printing that comprises
the majority of magazines and marketing materials you see
every day.
At some stage your RGB file
must be translated to CMYK in order to print it on a printing
press.
It's Best If You do the RGB-to-CMYK Conversion
of Your Images
You will have more control over the appearance of your printed
document if you convert all of the images from RGB to CMYK
before sending them to your printer, who normally will do
a standard-value conversion to CMYK, from your RGB file,
which may not be perfectly to your liking.
It is worthwhile to take time to prepare your files correctly,
as your printer won’t be responsible for sub-par results
when images are supplied in RGB. – Although monitors always
use RGB to display colours, the colours you see on your
monitor will more closely match the final printed document
if you view them in the CMYK colour space.
Be aware that it is possible to see colours in RGB that
you can't make with CMYK. They are said to be "out
of gamut". What happens is that the RGB-to-CMYK translator
just gets as close as possible to the appearance of the
original and that's as good as it gets.. So it's best to
select any colours you use for fonts or other design elements
in your layout using CMYK .
Here are some examples of how various RGB colours convert
to CMYK:
|
rgb colours
(will look like this)
|
cmyk colours
(printing inks will do this)
|
|
rgb colours
(will look like this
|
cmyk colours
(printing inks will do this)
|
|
You probably won't notice this kind
of colour change in a colour photograph. It is more likely to happen if you
pick a rich, vibrant colour for a background or
some other element of your layout. It probably won't
look bad, it just won't look exactly the same. |
Page
updated 17th July 2004
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