RGB, CMYK and the Pantone Matching System (PMS) are simply ways of defining colour in print and onscreen. Pantones are predefined colours (similar in concept to the paint swatches you’d find in a DIY store), and RGB and CMYK are recipes for creating millions of colours using only three or four base colours, because it’s simply not practical to have each colour separately presented on screen or printed from individual inks.
RGB: This is the model (recipe) that screens use (TVs, monitors, iPads/Tablets and mobiles etc). By using different mixes of Red, Green and Blue a vast array of different colours can be created in a similar way to natural light. And in common with light, this is an ‘additive’ colour system which means the more of Red, Green and/or Blue you add, the lighter the output colour is. So for example, if there is no Red, Green or Blue then the screen will be black. Adding the three RGB colours in different quantities will give you millions of shades and hues and if you have a ‘full’ intensity of each colour, the light — and therefore the screen — will be white. The RGB gamut (i.e range of shades or hues) is vast, but not as large as the visible spectrum.
CMYK: This is the model used for print and is composed of Cyan, Magenta, Yellow and Black (K stands for ‘key’) in various combinations. It is a ‘subtractive’ system — the more of each base colour you add the darker the finished colour. The CMYK range (or gamut) is smaller than the RGB one and has some specific limitations – it can’t represent some ranges of greens, blues and purples, generally ones that are intense and very vivid. However it still produces a remarkable number of colours, as you may now appreciate next time you pick up a magazine, catalogue or colourful book cover. Generally all these will have been printed in CMYK, and definitely so in the case of any photos on the page. Look carefully and you may see the fine dots of each colour that when laid down in a particular pattern produce the effect of a solid image. In theory, black can be created from C,M and Y, but in practice, it produces a muddy brown or similar so the key (K), which is generally black, is used to create darker shades and to print true black text.
Pantone (PMS): These are what’s called ‘Spot colours’. Most printed material uses the CMYK model above as it is the most efficient way to create a huge range of colours, however it can’t represent every colour and this is where Pantones come in. They are predefined by the Pantone company and can be purchased as premixed inks so that they are exactly the same every time. Also, by using Pantones, it means that it is easier to maintain colour accuracy – with CMYK being a mix of 4 colours slight changes in the relative mix of the four component colours can affect the output colour, whereas Pantone colours are applied as one ink directly to the paper. This makes Pantones great for maintaining brand colours accurately, it’s not practical to print every colour as separate PMS colours – it would take much longer and cost far more to print.
What should I be aware of?
- RGB images that you intend to use for print may change in colour when converted to CMYK. Photographs are usually fine, but graphics (icons, diagrams etc) with areas of solid colour may look different if those colours are outside the range (gamut) that CMYK can replicate.This usually happens to very vivid greens, blues and purples. Your designer/printer should be able to advise
- It may sound strange, but if you have large areas of black it is best to create a ‘rich black’ to make it look blacker when printing in CMYK. This is because black ink on its own does not look ‘black’ enough due to the way the ink is laid down on the paper (to avoid saturating and it and causing distortion). Rich blacks normally have 50% cyan or magenta added to them to give them a much darker and richer feel
- Pantone colours are the preferred model for creating logos, because then you are starting from a standardised colour definition – and Pantone produces ‘Colour books’ which show exactly how the colour will look. Although you can convert from Pantone to CMYK and RGB, all software and online conversion systems produce slightly different mixes of the colour because they are effectively creating a ‘nearest approximation’ to the colour required and there are different ways of calculating the mix. Therefore if you design your logo using CMYK or RGB colours you’ll be making colour decisions based on an ‘approximation’ on your screen or something you have printed out – neither of which has a standard calibrated output in the way Pantone does. Viewing the logo on a different screen, printing on different paper or using a different printer will alter the result. These sight variations are not normally too much of an issue, but when trying to maintain brand colours in logos etc it is much more important.
- RGB files of graphics which have a black or grey element to them when converted to CMYK can produce ‘muddy’ results. This is because any part of these files that look black will actually be produced out of a mix of all the constituent colours. It is much better to use the original ‘Vector’ files for any logos and graphics that you use and make the conversion from Pantone to CMYK at the print output stage (i.e when creating the PDF – or leave this to your printer) – this will produce the best result
As experienced graphic design consultants, we at Pixooma understand the importance of knowing how to work with different colour models. When designing for print we produce all our final files in CMYK and are aware of the limitations of this system throughout the design process. When supplying work intended for screen-use we focus on RGB, and when designing logos we create vector files which allow us to use Pantone ‘Spot colours’.
If you have any questions regarding colour models please contact us and we’d be happy to advise. And to get helpful articles such as this sent directly to your inbox simply sign up to our mailing list.