RGB and CMYK Colour Models

As you start working with Adobe Photoshop there are two colour models that you need to be aware of. These are the RGB(Red, Green, Blue) and CMYK (Cyan, Magenta, Yellow and Black) colour models.

RGB is important because it mirrors the way the human eye perceives colour. It is the model used by scanners and digital cameras to capture colour information in digital format, and it is the way that your computer monitor describes colour.

Red, green and blue are referred to as the ‘additive primaries’. You can add varying proportions of the three colours to produce millions of different colours – but still a more limited range (or ‘gamur’) than in nature, due to the limitations of the phosphor screen coating of the monitor. If you add 100% red, green and blue light together, you get white. You produce the ‘secondary’ colours when you add red and blue to get magenta; green and blue to get cyan; red and green to get yellow.

The CMYK colour model is referred to as the ‘subtractive’ colour model. It is important because this is the colour model used by printing presses. If you subtract all cyan, magenta and yellow when printing you end up with the complete absence of colour – white.