Difference between RGB, CMYK, Hex & PMS

Here’s a quick summary of the differences between the different colour spaces and a brief explanation as to why you’ll never be able to easily colour match between them. This is really important as the design that you see on the screen might not necessarily look the same when printed and may look different when printed on different digital colour printing machines and when lithographically printed.

As you’ll probably be aware, the human eye can detect somewhere in the region of 7000000 different colours. The reproduction of these colours in different mediums however is much much less due to the limitations of colour gamuts (what can be displayed in those various mediums). These are known as “colour spaces.” Colour spaces can include but are not limited to Pantone(PMS), RGB, CMYK, Hexachrome, YUV and so and so forth.

Different colour spaces are used for different processes and many of them are not interchangeable.

RGB (Red, Green and Blue) for instance are used in the display of digital colour images on screen i.e televisions and computer monitors. These images are displayed by firing red, green and blue pixels onto the screen which the human brain compiles into a single static or moving image.

CMYK (Cyan, Magenta, Yellow and Key/Black) is used to create a full colour image in print. This is done by laying down dots in a screen (there are many types of screens and screen sizes) on a substrate (card or paper etc) Again the human brain compiles these dots into a single colour image. Unfortunately because CMYK uses only 4 colours, the overall gamut that can be achieved is limited. A few years ago a new process was introduced called Hexachrome which added a green and orange into the CMYK mix so as to achieve a greater range of achievable printed colours.

The Pantone Matching System (PMS) is an alternative way of presenting colour in a printed image. Due to the CMYK process being limited in what can be achieved colour wise, Pantone introduced a system of “spot colours.” These are created using a much wider base of colours and are mixed in varying percentages to achieve a much closer match to the required printed colour. Spot colour printing in certain instances can be more expensive but will be necessary to achieve something like a company brand where CMYK is unable to meet the specific colour requirement.

Taking the above into consideration (particularly when you look at the RGB colour gamut) you can see that it would be impossible to match either CMYK or Pantone or in fact any of the many colour spaces to the values dictated by RGB as they are produced in a totally different way (one using electronic pixels and the other using printed dots) Unfortunately, it is only possible to achieve a very loose colour match if at all.

The overall colour range is that which is visible by the human eye. Contained within the image are the colour spaces I’ve described. As you can see what is achievable in print and on screen etc does differ and is considerably less than what we can discern with our eyes.

We hope this helps you understand why colour matching is so important and how what you see on your screen may differ from the final printed result.