RGB vs CMYK - colour spectrums explained
If you’re working with a designer, or you’ve tried sending a document to a printing service, you’ve probably heard the terms “CMYK,” “RGB,” and probably “colour conversion.” It’s not nearly as technical and intimidating as it seems, I promise!
To put it simply, they both refer to their own colour spectrums, and, depending on what you plan to use it for, your design must comply with a specific spectrum.
Essentially, if you’re creating something for print, you need to use CMYK colours. If you’re creating something for digital use, you need to work with RGB colours. And the reason is very simple: we can physically produce far, far fewer colours to apply to paper -we’re confined to what we can create from CMYK (Cyan, Magenta, Yellow, and Black). However, on a digital platform, we can create trillions upon trillions of colours from RGB (Red, Green, Blue).
So, then the question becomes, what do you do if you’re designing for both print and digital use? The answer? Design in RGB. Always. Design in RGB, then, when you’re finished, duplicate the design and convert it CMYK. RGB will produce far brighter, more vivid colours on your screen than CMYK will, and a computer is very good during a colour conversion at finding the closest CMYK comparison to an RGB colour. However, because CMYK colours can be found within the RGB spectrum, computers will never take a CMYK colour and look for a more vivid RGB version during a conversion, because they’ll assume the colour you chose is the colour you want.
You can see from the example above that the CMYK is duller and appears ever so slightly grainier because there are less colours at the computers disposal so the gradient isn't as smooth.
Lastly, let me follow up by mentioning, that almost every piece of artwork a design generates for you should be provided in formats that are both ready-to-print and ready for digital use. If, for any reason, you haven't been provided with these, and need to make a colour conversion, simply:
Open your source file (PSD, AI or INDD)
Go to File -> Document Colour Mode (for AI); Image -> Mode (for PSD); or Edit -> Transparency Blend Space (for INDD)
Select the option that indicates the spectrum you require.
Export the document as the file type required - read more about the various file types here
If you have any problems with existing artwork, feel free to give me a shout at firstname.lastname@example.org and I'd be happy to help you out.