Differences between CMYK and RGB colour model

CMYK is a colour model used in printing, and RGB – in computer environments and colour television.

In the CMYK model, the primary colours are superimposed to obtain the black colour, and in the RGB model, the white colour is formed from the superimposition of the primary colours.

The CMYK Colour model - the abbreviation CMYK is formed by the words of the four main colours: Cyan (cyan - basic blue), Magenta (magenta - purple red, tending to red), Yellow (yellow), Key or black (for black). Removing these colours produces a white colour. Theoretically, a mixture of cyan, magenta and yellow should give a black colour, but it does not, so black is added.

The numerical value of each colour element of the CMYK system is between 0% and 100%, where at 0% the specified colour element is not reproduced, and at 100% it is reproduced completely

The RGB colour model – Computer monitors create colours similar to television receivers – by emitting three rays – Red, Green and Blue light. In this model, the three primary colours are combined to produce the remaining. 256 values are possible for each of the three colours.

Practical tips for using these models:

* When creating colours in the CMYK system, you can use the following proportions:

White – C=0%, M=0%, Y=0%, K=0%

Green - C=100%, M=0%, Y=100%, K=0%

Red - C=0%, M=100%, Y=100%, K=0%

Yellow – C=0%, M=0%, Y=100%, K=0%

All colours must be used to obtain the black colour, and the total value must not exceed 300%. The following proportions can be used for a solid black colour C=60%, M=60%, Y=60%, K=100%

* When scanning illustrations, photos, pictures, etc., the resulting files are in RGB colours. Therefore, if we want to print them, it is recommended to convert them to CMYK colours through the appropriate programs. When creating files to be printed, it is recommended that they be created in CMYK colours.

* When creating web documents that will only be viewed on a monitor, it is better to have them in RGB colours, as this will reduce the file size.