A look at the three types of Colour process us designer types refer to and how a bit of knowledge saves you money and time!
There are essentially three colour processes that designers will usually mention when working with you. RGB, CMYK and Pantone (or Spot). RGB is a digital screen based colour mode used for things like web design and other applications that will be viewed on screen. CMYK and Pantone though different from each other are for print. Knowing the differences can save a lot of time and even money!
So what’s the difference between them? We’ll start with RGB.
RGB is a screen only colour system that isn't suitable for commercial print. RGB refers to the Red Green and Blue light emitted in the from of pixels on a screen. The three colours are mixed in different intensities to achieve the millions of possible colours that you’ll see on your computer, phone or other device. The most important aspect here is perhaps the fact that the colours are created using light. They are mixed using the 'additive' colour mixing process. We won’t go into science here but will simply say that the results can be extremely “bright” colours. Imagine looking at a bright light bulb or LED. Many of these colours aren’t achievable in print and that’s an important thing to note.
CMYK (Four Colour Process) on the other hand is a colour system for printing that relies on the optical mixing of four coloured inks, Cyan, Magenta, Yellow and Black. You may have noticed that Black doesn’t begin with K. It’s thought that the K actually stands for Key, a derivation from early printing processes, but let’s not get bogged down in that. For our purposes “Black” best describes the actual hue being used. In process printing the four colours in a CMYK file are separated from each other into individual plates for each of the four colours, made up of dots arranged at different angles. Each of the four inks is transferred to it’s corresponding plate one at a time and run on a printing press, with each colour overprinting the previous. The resulting composite of the 4 layers of coloured dots fools the eye into mixing them together to create the illusion of a full colour image. It’s similar in principle to Pointillist painting but on a tiny scale. One of the most important distinctions we need to make is that CMYK can’t reproduce all of the bright and intense colours available in RGB.
So why is it so important to know that CMYK can’t achieve colours that RGB can? To give you an example, we have worked with a client who had had their logo designed by another designer right at the start of their business venture. Part of the colour scheme was bright orange. The client was happy with the way the logo looked on screen in presentations and signed off the design. However, as time went on and they had more and more printed material produced with the colour scheme, they noticed that the lovely warm bright orange that they had approved was printing as a dark muddy colour. This is because the nature of the CMYK process means it just can’t create bright oranges and many other bright and vivid colours. Another issue was that they were not given any guidelines as to what the colours actually were in terms of CMYK or RGB values / percentages. This has led to the client having to rethink the colour palette used. However the orange is so much a part of their onscreen identity now, they were reluctant to change it.
Now, this is where Pantone or “Spot” Colour can lend a helping hand. The Pantone system uses premixed pigment inks, much like the artist's paint you get in shops, that are defined in a formula guide as mixtures from a set of 18 base colours. The fact that there are 18 base colours to mix from versus the 4 of CMYK mean that the gamut of available colours is much wider. The nature of the ink means that the colour is already mixed before it hits the paper, it isn’t mixed by the end user, usually the printer, and so there are no dots for the eye to mix. The colours that are achievable range from those available in CMYK to much brighter colours and even some that are metallic or luminous. This means that the orange that the client had seen on screen was achievable on paper after all. So we worked with them to define what the orange is, to keep everything consistent, in terms of it’s RGB mix and which Pantone colour it is. The issue that arises however, and there’s always a catch isn’t there?, is that the use of Pantone, when combined with CMYK means that you are effectively adding a fifth ink to the printing process, which means a fifth plate that the printer has to make and so it becomes more expensive if you have to use that Pantone colour every time you go to print. It also makes low cost short run digital printing, which is becoming more and more popular due to low cost, less viable. So that early mistake made when designing the logo is now costing the client money in the long run!
There are plenty of other factors to consider when looking at colour consistency and reproduction, including variation in CMYK from printer to printer and also the paper stock onto which you print, however just knowing the differences between, and pitfalls of, these three colour systems can help you no-end in working with your designer, on your own and with your print shop.
Knowing this distinction, which our client now does, empowers them to make choices about what they are being shown on screen. They are able to question whether or not a design being translated from on screen, i.e a web site to off screen promotional materials will work in terms of colour. They can ask their web designer, for example, “How will those colours print when I come to produce my business card or brochure?” or consider whether they actually want their logo to be bright orange after all!