The difference between RGB and CMYK
Our system does accept RGB color files and automatically converts them to their CMYK equivalents for printing, but the color conversion is not always perfect.
Any technological device, whether computer monitors, TVs, phones or LCDs, use an RGB color profile. This is because an RGB profile uses red, green, and blue light to make the different colors – there’s no ink in sight. To reproduce RGB files in print, you have to convert them to a CMYK format. Instead of blending light, this format blends Cyan, Magenta, Yellow and blacK ink to make the piece more printer friendly.
For more information on the differences between the RGB and CMYK color models, please read our detailed explanation.
We have also created a list of suggested CMYK values to help ensure bright, vivid colors when printing.
Converting RGB to CMYK
Unfortunately, RGB can’t be converted to CMYK directly. When switching from light to ink, some RGB colors become impossible to reproduce in CMYK. If a printing company claims they can print in RGB, alarm bells should start going off!
This isn’t to say that RGB to CMYK conversion is impossible. Our conversion guide will step you through the process in a convenient, easy-to-read format. When you successfully convert your RGB files to CMYK before submitting any artwork, you will have full color control when printing, including manually adjusting tricky colors.
Standard black vs. rich black
Offset printing has two main ways to produce black: standard black and rich black. Standard black is standard because it only uses black (the K in CMYK). Rich black, on the other hand, uses a mix of Cyan, Magenta, Yellow and blacK to create a richer, more intense color.
It’s worth noting that, when converting from RGB or greyscale to CMYK, you will automatically end up with rich black.
There are occasions when it is better to use standard black, not rich black. This is particularly important if have very fine lines, like small text or speech bubbles in comics. Even in a full color CMYK project, you should always use standard black. Otherwise, you run the considerable risk of ‘ghosting’, where the four ink plates needed to make rich black produce microscopic variations that result in a blurred shadow of unwanted color.
To find out more about standard black and rich black check out our comprehensive guide.
You can also check out our guide on full color vs black and white, because sometimes it’s actually better to print blacks in Full Color in order to get your blacks really black.
Color can look different on your screen compared to a printed page, because screens are backlit, whereas print reflects color. Your choice of paper and finish can also affect the appearance of your colors.
For best results, we recommend printing on satin paper, while uncoated paper will produce slightly muted colors.
CMYK always blends four colors of ink (cyan; magenta; yellow; and key, or black), which can produce very slight color variances between runs, and incredibly small color variances within different copies on the same run. If color is critical to your project, please get in touch with our print experts and we’ll give you the guidance you need to get the results you want.
In offset printing, very subtle color gradients can get lost, especially when ink saturations are very high. When this happens, your artwork could end up looking darker than it appears on the computer screen.
If your ink saturation values are too high overall, the printed result will appear darker than expected. This is especially true with deep blues and blacks. They may look incredible on a backlit screen, but will appear much darker in print if your overall saturations begin to exceed 300%.
In the case of single-color saturations, light ink coverage under 10% may not print at all, while coverage over 90% may turn out as a solid color.
Have a look at our saturation guide for ink coverage. It explains how to avoid extreme values and make sure that every detail of your print can be seen clearly.