The difference between RGB and CMYK
Our system accepts RGB (Red, Green and Blue, top) colour files. It will automatically convert them to their CMYK (Cyan, Magenta, Yellow and Black, bottom) equivalents for printing. But colour conversion is not always perfect.
Digital devices like computer screens, TVs and phones use an RGB colour profile. An RGB profile uses light to make different colours, not ink. To reproduce RGB files in print, you must convert them to a CMYK format. Cyan, Magenta, Yellow and Black ink blends to make your artwork printer-friendly. You can read about the differences between these two colour profiles here. And you can reference our CMYK values and formula charts to ensure you get bright, vivid colours when printing.
Converting RGB to CMYK
Unfortunately, you cannot convert RGB to CMYK colours directly. When switching from light to ink, some RGB colours are impossible to reproduce in CMYK.
But colour conversion is still possible. Our conversion guide will demonstrate how to do this in an easy-to-read format. Before submitting any artwork, you will have full-colour control when printing, including manually adjusting tricky colours.
Standard black vs rich black
Litho printing has two main ways to produce black: standard black and rich black. In CMYK printing, standard black only uses black ink. Rich black, by contrast, uses a mix of Cyan, Magenta, Yellow and Black to create a richer, more intense colour. Note that when converting from RGB or greyscale to CMYK - you will get rich black in your prints.
Occasionally, we recommend standard black over rich black. We recommend this option because if your print work includes fine details, like small text or speech bubbles in Comic Books.
Even in a full-colour CMYK project, you should always use standard black. Otherwise, you run the considerable risk of ghosting. Ghosting occurs when the four ink plates needed to make rich black produce microscopic variations that result in unwanted blurred shadows. But you can check out our comprehensive standard vs rich black guide for more information on this topic. Our colour vs black and white printing page will also show you examples of when it’s better to print blacks in full colour to achieve an intense black.
Colour matching
Colours on a screen appear different compared to those on a printed page. Screens emit light, whereas print reflects it. Your choice of paper and finish can also affect the appearance of your colours.
CMYK ink can produce very slight colour variances between print runs - and minute colour variances within different copies on the same run. If colour is critical to your project, contact us, and our print experts will give you the guidance you need to get the desired results.
In litho printing, very subtle colour gradients can get lost, especially when ink saturations are very high. When this happens, your artwork can look darker than it appears on the computer screen.
If your ink saturation values are too high, the printed result can also appear darker than expected. This result is especially true with deep blues and blacks. You may like how they appear on a backlit screen, but they can appear much darker in print if your overall saturations exceed 300%.
In the case of single-colour saturations, light ink coverage under 10% may not print at all, while over 90% coverage may produce a solid colour. But our ink saturation and density guide will explain how to avoid extreme values and ensure every detail of your print is visible.
