Thursday 25 September 2008

RGB aint CMYK

It's been another busy week at IP, but we have now finally got the time to add another exciting installment to our blog!
It occurred to me the other day, how confusing colour can be! Then I came across a fantastic article that explains RGB and CMYK extremely well. So if you were ever confused about what the printer is talking about when he is huffing and puffing that you have got your artwork in RGB, not CMYK, or you don't actually quite understand what the different processes are all about, then read on!

Colour is colour, right? Wrong! Depending on your application and use, there are two main colour referencing formats you will come across: RGB and CMYK. These two colour formats are for completely different uses, but the result of the two formats is the same to our eyes.

How do you know when each is being used? How does this influence your colour printing projects? These issues and others are the point of this discussion as we delve into the finer points of colour printing.

RGB: the primary colours of light
RGB is an acronym for Red, Green and Blue: the primary colours of light. When your computer monitor or television screen reproduces images, the three primary colours are mixed together in varying shades and strengths. The important distinction here is that light, rather than ink, is used to reproduce an image. Just because a picture looks one way on a monitor or television screen does not mean that it will be reproduced accurately on paper.

CMYK: the primary colours of ink
CMYK is an acronym for Cyan, Magenta, Yellow, and Black: the primary colours of ink. When your printer reproduces images, the four primary colours of ink are mixed together in varying shades and strengths.

You are probably noticing the pattern about now, in that RGB and CMYK do the same thing but in different ways. What you have to understand is that RGB references light and CMYK is ink.

What all of this means.
You cannot print in RGB and you cannot view pictures on a monitor in CMYK. So, to answer our first question of how to know when you are using which colour format, monitors display in RGB and printers display in CMYK.

A conversion process has to take place to go from viewing pictures on a monitor to view the same pictures in print. What's more, the conversion is not always perfect or accurate. In response to the question about how this impacts colour printing: there may be differences between what you see on the monitor and what you get back from the print shop. You can compensate for this by calibrating your monitor and through printing proofs to make sure your work is translating properly.

RGB and CMYK are fundamentally different. RGB is how monitors display light. CMYK is how printers reproduce images in ink. You can make sure your colour printing turns out as expected by using a calibrated monitor and by printing proofs to check for any colour variations.

Keep creative,

James

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