CMYK and RGB

RGB vs CMYK – what is the difference?

Firstly, let’s consider how we view a screen versus how we view the colours on the printed page. For a screen we see the light which comes from screen – the colour orange being created by the ‘addition’ of primary colours of light (Red Green and Blue) in different proportions

When we observe the reflected light from a surface of print, the orange is defined by the colours ‘subtracted’ from the white light shining on it (CMYK) - the Cyan, Magenta, Yellow and Key or Black

Thus we have two systems of colour definition, RGB (an addition system) and CMYK (a subtraction system).

All colour can also be defined as a PANTONE number – this is a system which allows printers to define the exact mix of cyan magenta and black (CMYK) inks to create a colour. The Pantone system is an international system of colour definition that ensures that artwork printed anywhere will be the same. Do not place the pantone book against your screen – you are comparing two different definitions of colour – and with a screen which in all likelihood is not calibrated!

If the printers artwork you were sent has a colour that does not ‘look right’ on screen – this is not surprising since you are comparing an apple with a pear. Ask for a hard copy proof or give the colours a Pantone definition.