Each person starting their adventure with computer graphics must face such concepts as CMYK, Pantone and RGB which refer to colour spaces. Together with Andrzej Kidaj, graphic designer and founder of Andy Design blog we decided to provide some insight into this subject.
CMYK colours and RGB colour — how do they differ and do they need to be in two spaces? The answer, in a nutshell is that they differ mostly by their principle of operation and yes, they do require to be in two spaces.
CMYK for printing
This abbreviation comes from the English words: Cyan, Magenta, Yellow and blacK. Cyan is a light blue colour which is called blue-green in CorelDraw. Magenta is a shade of pink, although also crimson can be encountered here. The graphic circles simply use the English names and this is fine. Also here, if we look at the printout closely, we can see dots in appropriate colours. The dots are called halftone and this model is called subtractive as the sum of three CMY components should form the black colour. It should however the printout is not perfect and after overprinting all the colours we get something brownish. To prevent this a separate black colour was added.
We were taught at school that blue, red and yellow are the primary colours from which all the other colours can be obtained. Forget it, it’s nonsense. You will not get pink. The truth is that Cyan (blue is obtained after mixing it with Magenta), Magenta (red is obtained after mixing it with yellow) and Yellow (i.e. yellow) are the primary colours.
RGB for the screen
RGB is also an English abbreviation made up from the following words: Red, Green, Blue. Monitors work in this space. If we look closely at a screen, we can notice that white is not white at all, but it consists of three dots placed near each other: red, green and blue. These are so called sub-pixels and the brightness of each of them defines the average colour that our eye can see. This space, for a change, is called the additive model — the white colour is obtained after adding all the components. RGB is a ‘broader’ space which contains more colours than CMYK. Special care should be taken while preparing a design which uses bright, neon colours, e.g. bright orange, as it will not look the way we would like it to after printing. It is easy to check this in Photoshop by pressing CTRL+Y to get a preview in the CMYK mode.
What should we pay attention to while printing?
There are no major problems with digital as we generally get what we see whilst designing (different recipients may observe slight differences resulting from an uncalibrated monitor), but printing involves many more pitfalls. Therefore, as we know, designing for printing requires some experience and those who ignore these specs will ultimately pay for their error. Literally because the whole print run must be printed again! So what should you pay attention to?
- Printing machines are not perfect and each colour is printed separately. So matching errors may occur (it can be seen especially on cheap printouts). The colours fall apart slightly and fine texts cannot be seen if they consist of several components. Therefore, information in fine print should be preferably black and, if they are against some background, they should have the overprint option set so that no white frames appear. White letters on a dark background is asking for trouble.
- Shadows should be also overprinted (or be in the multiply mode). What looks good on the monitor (e.g. the colour of the background) may look terrible after printing because the background colour disappears (‘superseded’) and black appears gradually — this doesn’t look anything like a shadow.
- They say everything works on paper. This is not true. There is a parameter called total ink limit (TIL — ask about it at the print shop). It usually amounts to approximately 300% and means that the total of all the components may not exceed this value. It is particularly important for the creation of so-called ‘rich black’. If we use only the black component for the background, it will look grey in print, so some other colours must be added. And if we add all of them in maximum amounts, this will give us 400%. As a result, the print will be seen on the other side of the page, it can become blurred (this is very likely to happen), the printer will swear at you (the majority of cheap print shops do not check this before printing) and your boss will probably not be happy about the costs of reprinting the material. It should be remembered that there are tools (e.g. in InDesign) for checking the total ink limit — use them.
And what is this PANTONE for?
These are the predefined additional colours that often cannot be obtained using CMYK, e.g. gold. silver, orange and all the colours classified distinctive or bright. Obviously, each additional colour means additional costs, so they are not used very often and certainly not for printing photos. Pantone colours are usually used for vector elements, e.g. a logo on business cards (this is why logos are often described using RGB, CMYK and Pantone colours in sign books). As CMYK components have different proportions with many colours and visible halftone appears in print, Pantone allows us to avoid this. It can also be used for writing fine texts. Forget about Pantones if low volume digital printing is used — these machines use only CMYK.
PANTONE for photos
There are situations (rare but they happen) when the usage of Pantone for printing photos reduces costs in comparison to the standard CMYK. Usually we use black colour and one of Pantone colours (so called dual tone) or black and two Pantone colours (triple tone). Of course, the photos must be appropriately prepared, but the effect can be interesting.
Remember to use the colour chart
It is true that software allows for automatic conversion of a colour from CMYK to Pantone, but the effects are rarely satisfactory. Everything depends on the calibrated monitor and the software, and the result (I know this from painful experiences) can be completely unexpected. To select the right colour you can use Pantone colour charts in which you need to find a suitable colour manually (and visually) taking into account for example the type of paper — coated or uncoated etc.
I hope that I managed to shed some light on this subject to all those who are at the beginning of their career in graphic design. Unfortunately, it takes a long time to master issues related to CMYK, RGB and Pantone, and the process involves making mistakes however always learning from them so keep your chin up!