CMYK and RGB – some of the facts Part 1.

CMYK and RGB have long been the discussion points of many forums. What is the difference? What do they stand for? Over the next few articles we will bring you some of the facts of these two abbreviations!

The CMYK colour model – also referred to as process colour or four colour is used in colour printing and is what is known as a subtractive colour model. CMYK stand for cyan, magenta, yellow, and key (black) and is often used to describe the printing process itself. These four colours of ink are used in offset printing. The ink is usually applied in the order of the abbreviation – CMYK.

“Why is black ‘K’ in CMYK?
In four colour printing, the CMY (cyan, magenta and yellow) printing plates are aligned (or keyed) using the key of the black “key plate”. Hence why the K in CMYK stands for key. It has also been suggested that the K is taken from the last letter in the word “black” due to the B already being used for the word Blue.

Masking colours on a lighter background, usually white, is how the CMYK colour model works. The ink works to reduce the light that would normally be reflected. This is why such a model is called subtractive, because the inks subtract brightness from the white.

RGB colour models are the opposite, the are additive colour models. White is the additive combination of all primary coloured lights while black is the absence of light. The CMYK model is the opposite to this, where white is the natural colour of the paper (or other background) while black comes from a full combination of the coloured inks. To make deeper black tones (and to save money on ink of course), unsaturated and dark colours are often produced by using black ink instead of the combination of CMY (cyan, magenta and yellow).