Four Colour Process Printing - What is four colour process printing?
A method of multi-colour printing; this process uses four process colours that are combined to create the required colours. Sometimes known as process printing, this process involves layering the required process colours onto a substrate in multiple runs to produce the correct colour. The four colours are Cyan (Process Blue), Magenta (Process Red), Yellow (Process Yellow), and Key (Black).
The CMYK model creates colours through a subtractive combination of process colours; starting with white, each process colour that is added will absorb certain wavelengths (colours) of light rather than reflecting them (subtracts them from white).
In order to be able to produce a continuous range of colours, process colours are printed as halftones (tiny dots of colour). The dots are so small that the human eye perceives a pattern of dots as a solid colour; by adjusting the size, shape, and spacing of the dots, the saturation of a process colour is increased or decreased, allowing a continuous range of colours to be produced. The inks and toners used in process printing are usually translucent; this allows the process colour to be layered as needed. Colours are usually specified and identified by listing the percentage of a halftone that is printed in each process colour (if a process colour isn't required, it is listed as 0%).
While four colour process printing can produce a wide range of colours (and is used for full colour printing), it is reliant on the optical effect of halftones and the combination of just four colours and simply cannot produce a full, unlimited range of colours. To expand the range of colours that can be produced, different versions of process printing may be used; Pantone's Hexachrome model expanded the range of CMYK by adding two more process colours (orange and green), and the CcMmYK process adds a light cyan (lower case c) and a light magenta (lower case m) to overcome problems with printing light shades of these two colours.Go Back to Glossary