Knowing the difference between RGB and CMYK

Without understanding the key differences between RGB and CMYK in graphic design,

you could very well get a shock when seeing your printed marketing materials with colours you weren’t expecting. The mockups looked great on screen so what happened?

It is simply because RGB and CMYK are two very different colour codes—each with their benefits and restrictions. Printing a design in RGB format will no doubt turn out misconstrued colours, leaving you with an unnecessary waste of time and money. Let’s take a look at how this can be prevented.

You may have seen these acronyms here and there.  So what do they mean?

RGB vs CMYK  – which is best for what you need?

Let’s start with what RGB stands for. Red, Green and Blue.

For any media that transmits/emits light, computers and mobile phones for example, RGB is the best choice. This is because these mediums use light to create colours. They are made up of pixels—red, green and blue lights. When white light passes through the pixels it creates a greater spectrum of colour to our eyes. Varied brightness levels create different colours. These are called perceived colours and there are more of these on screen than you could ever get through printing. As the device emits more and more colour the closer it gets to white and, you guessed it, not emitting any beams we get closer to black. Think of it as when you flick on your light switch. Creating colours using the RGB method we use values ranging from 0 – 255.

For printing marketing materials the best files are in CMYK. Think of CMYK as a buildable colour code. When a percentage of Cyan, Magenta, Yellow and/or Black inks are combined they create the specific colour. White in this case is used as the naked printing material (paper for example) and black is created through the use of adding coloured inks.

During printing, these colours are formed through thousands of tiny dots of ink. The more layers of colour added, the darker the colour. Printers also use spacing between where the dots are put on paper to determine colour. The more spread out the lighter the colour, the closer they are the darker the colour becomes. Creating colours with the CMYK method we use percentages from 0 – 100%.

How do I convert an RGB file to CMYK for printing?

RGB is wonderful in that it has an extremely wide range of colours, or gamut as it is formally called, compared to CMYK. When it comes to converting colours from RGB to CMYK there will be a significant loss in colours available. As inks do not emit any kind of light it is impossible to replicate the perceived RGB colour spectrum you would find on screen through to paper.

 

Here’s an example. Say you are looking at a mockup of a website design. The design should have been done in RGB as it is the best choice for screen. If you were to print this file in RGB you would more than likely have a printed version with varying colours to that on screen. By converting to CMYK, you are asking inks to do their best in replicating the vivid more vibrant colours lights make on screen and in a way trick the eye to see similar colours.

Here are simple ways of converting an RGB file to CMYK through Adobe software:

Adobe Photoshop CC

In the top menu options find Objects > Image. Click “Mode” and look for “CMYK Color.”

Adobe Illustrator CC

Menu select Objects > Edit

Click “Edit Colors,” and select “Convert to CMYK.”

What happens if you forget to convert your file? The printer will convert it automatically. This may sound like a great choice but you won’t have the chance to see or edit the colours the printer converts to until it spits out. By that stage it is way too late to edit. Save yourself an expensive headache and remember to convert to CMYK.

About the different colour spaces

If you are interested in exploring the differences between RGB and CMYK in greater detail, we recommend looking at colour spaces. Colour spaces are dedicated ways of using colour models. Within the RGB and CMYK models are numerous colour spaces that hold their own individual gamut or colour spectrums. Adobe RGB and sRGB are two of the more frequently used coloured spaces. sRGB or Standard RGB is a colour space that you and most of your website visitors would have no trouble seeing through their screens.

Did you know that Adobe RGB holds the widest spectrum? Depending on your monitor, it may not reproduce all the colours available. If you know the design is destined for printing then using the Adobe RGB colour space is A-OK! This does depend on the printer being modified for Adobe RGB.

The best, and often safest way, is to contact your printer prior to sending your file so you know exactly what they require. Feel confident knowing your marketing materials will come out the way expected.

In a nutshell

So remember, any designs destined for mediums using screens like mobiles and television, it’s best to use RGB. For files that need to be printed make sure they have been converted to CMYK and enjoy beautiful colours across your entire brand.

Experienced graphic designers and agencies will provide you with logo files in RGB and CMYK versions to make your life easier—just pick the colour mode best for the destined medium. This goes for all your images too. We hear many cases of clients receiving one file and have no choice but to use it on all mediums which is far from ideal. Now you know what to look out for. It must be said that no colour model is 100% accurate but does a pretty good job of convincing the eye.