To RGB or CMYK

RGB.

RGB is the colour scheme associated with electronic displays such as CRT, LCD monitors, digital cameras and scanners. It is an additive type of colour mode that uses the three primary colours (Red, Green and Blue) in various degrees to make different shades.

All three make pure white when mixed at their full extent, while all three mixed at their lowest setting make pure black.

RGB offers the widest range of colours which is why photo editing programs use it.

CMYK.

Printers use the CMYK colour mode and can produce colours that are more vivid and bright. It consists of the four colours Cyan, Magenta, Yellow and Black, and uses these to produce other shades when printing images.

Unlike RGB, CMYK is a subtractive process, which means that each additional unique colour is removed to create the colours. When the first three colours are mixed, they create a dark brown and 'K' or black is added to removed light completely which is why the eye perceives it as black.

Summary

The RGB colour mode has a more varied range of colour than CMYK and can produce vivid and vibrant shades. Colours that are beyond the range of CMYK and so images created with the RGB palette will come out darker when printed.

To accurately print the document or image, it must be covered from its original RGB format to CMYK. It is possible to do this using software like Photoshop and Illustrator.