That’s not what it looked like on my computer …


Ever wonder why certain colours look different in print and on your computer screen?

This is because they use very different types of colour management systems. Commercial printing uses the CMYK process. Computer monitors use the RGB system.
CMYK refers to the four ink colours used in color printing: Cyan, magenta, yellow and black.

Originally colour printing was produced on metal plates, and each colour had its own plate.  The black plate was referred to as the “key” plate, as it contained important information about the file.  Hence, black is referred to as “K”.

In a four-colour printing process, the full colour spectrum is created by combining varying amounts of cyan, magenta, yellow and black.

RGB means red, green, and blue.

When all three colours are combined, they create white. In the color printing process, these underlying tones must be changed into CMYK.

The biggest difference between CMYK and RGB is the way that they produce colour:  Monitors emit light, and paper absorbs light.

CMYK are subtractive shades.  When cyan, magenta and yellow are added together, black is created.   So they start with all the shades, and as the colours are subtracted, the colours produced will become lighter until nothing is left and the paper is white.

RGB colors are additive. PC monitors are black, so light is incorporated to generate colour. The screen will appear white if all three shades are combined at a 100% density.

The printing process itself works through the absorption and reflection of wavelengths of which we perceive as color – and this is how the CMYK model works.  Cyan, magenta and yellow are laid over each other to reach the desired hue, with black used to adjust the depth or darkness.

While the RGB process can produce all colours on the spectrum, monitors are limited in what they can display.  In addition, individual monitor factory specifications and settings can vary widely, causing even further differences in colour.  This is why RGB images must be converted to CMYK in order to be printed commercially, to ensure the highest quality printing.  Ideally, your projects should be created using CMYK to avoid any quality loss from conversion.

If you have any questions about colour printing, give us a call and we’ll make sure your projects are produced at the highest quality.