Print School - Ever wondered why your colour printing doesn't match your screen?

Print School

Ever wondered why your colour printing doesn't match your screen? Frederick Law is here to explain.

Colour Modes - RGB vs. CMYK

A common error when delivering images is the difference between screen and printer colour modes. RGB (red, green, blue) is one of the most widely used colour modes and is used on computer screen monitors for display. CMYK (cyan, magenta, yellow) however is the only right colour mode for print. This explains why when you print some colours come out different to how they are displayed.

RGB

Right now you are reading an RGB display via your computer. RGB stands for Red, Green and Blue. The three colours that create every other tone of colour that is visible on your screen. There is no black or white ‘colour'. Neither is there yellow or purple. They are all combinations of red, green and blue. White is the sum of all three colours while black is the absence of all three colours.

CMYK

In four-colour process (CMYK) printing, primary colours (Cyan, Magenta, Yellow, and Black) are mixed together to produce most of the colours that you see in normal magazines and colour books. Cyan, magenta and yellow are subtractive colours. If we print cyan, magenta and yellow inks on white paper they absorb the light shining on the page. Since our eyes receive no reflected light from the paper, we perceive black.

The printing world operates in subtractive colour, or CMYK mode.

So, why does this matter?

One of the most common errors with printing is where RGB is used to create a document or image without allowances for the use of CMYK printing. Files must be converted to CMYK for printing purposes, causing usually only minor changes. However, sometimes the colour range can be altered causing a complete change in colour tones. Be warned that deep RGB blue can never be replicated by CMYK.

Tips on producing a design which will print well in colour
•Many programs, such as "Photoshop" and "Microsoft Publisher", have a CMYK mode option; while you are working you can switch to this mode to see exactly how your design or document will print. Though it is important to remember not to make repeated changes between RGB and CMYK views as every time a switch occurs a little clarity is lost. One switch is no problem; 20 switches make a difference. You may be wondering why we don't simply work in CMYK all the time. RGB files are 25 faster to work with and store.
•Be aware that it is possible to make colours in RGB that you can't make with CMYK.
•Colour photos don't suffer much from CMYK translation but ensure the resolution is high enough to get a good quality finish.

If this article has been helpful visit Frederick Law's Print School for similar helpful articles on printing problems.

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