RGB vs CMYK colour spaces explained

When seeing one of their freshly-designed, newly-branded print products for the first time, our clients sometimes ask “Why do my brand colours look different in print?”. They would be forgiven for spotting a discrepancy in colour values, and they are not wrong. However, neither are we. Colour inconsistencies do exist, but there’s a reason for it. And this is where the RGB vs CMYK debate comes in.

The common explanation for this colour difference is that the colours we pick for our clients are chosen from a palette (or range) of RGB colours. It’s these colours that they often see first in design projects on screen – yet when they see the CMYK equivalent, it can look very different. In this post, we’ll explore the different colour spaces and how colour profiles can differ depending on the file format, design software, and, most importantly, from digital images to print files.

What are the different colour spaces? RGB vs CMYK

You might have heard of the CMYK and RGB colour spaces before. If not, here is a quick breakdown to offer you a basic understanding:

CMYK stands for cyan, magenta, yellow and key. In traditional print colour separation, the key plate holds the most detail in the image. The remaining ones (usually cyan, magenta and yellow) are carefully aligned with the key plate. As the key plate is usually black in print jobs, the “K”, in essence, stands for black. CMYK is thus a subtractive colour space because, on a piece of paper, each layer of ink reduces the initial brightness, by absorbing some of the light wavelengths and reflecting others, depending on its characteristics. When colour is created by subtracting wavelengths of light from a white paper or other materials, it results in subtractive mixing.
RGB stands for red, green and blue. These are the primary colours of light, used by screen-based media. The RGB colour space is formed by the pixels on the screen shining at different intensities. At full intensity, all three colours create white light. Alternatively, the absence of all three colours (aka without any light source) results in black. Each light or pixel can shine at an intensity between 0 and 255. So, RGB is an additive colour model, as colours in RGB are created by the additive mixing of light.

So, why do your colours look different in print files?

In the subtractive colour space, the cyan, magenta and yellow pigments in printing are too transparent to create opaque colours. So, black needs to be added separately. As discussed, in CMYK, colours are created by completely or partially absorbing some light wavelengths and reflecting others. This is the way colour is perceived when looking at all objects other than at a screen. It’s the texture of an object’s surface (sometimes resulting from the application of a pigment applied to said surface) that allows certain wavelengths of light from the visible colour spectrum to be reflected back to the eye.

Put simply, RGB is the way colour is produced on a digital screen and CMYK is the way colour is produced when pigments are used in print on paper or other materials – and they produce quite a different range of colours.

RGB colour capabilities often result in punchier, more vibrant colours than CMYK. So, print struggles to replicate the saturated colours of screen-based media. RGB mode creates the maximum colour combinations, with 16.7 million colours compared to CMYK’s 16,000 possibilities. This image best shows the differences between the colour spaces:

image explaining colour gamut

So, when you see your new brand colour in print form, or even as PDF files on screen for the first time, the CMKY version of the colour will likely look different – perhaps duller – from the RGB version you are used to. Even more, if you are viewing a PDF proof of print artwork on your monitor, your RGB-based screen will try to render the CMYK colour data as something resembling the correct colour.

And before you ask…

At Dusted, our designers start work on your brand development by using RGB colour pallets, as most of the work we produce is screen-based. However, when writing your brand guidelines and defining the colour information for your CMYK pallet, rest assured, we do our best to choose a CMYK recipe that represents as close to an exact match of the RGB version as possible.

There’s more! Digital design, colour matching, and keeping your colours consistent

The difference between these two common colour spaces is just one part of the bigger picture which is colour management. As you dig deeper, you find different types of RGB depending on the device you are looking at, as different devices can have different colour gamuts depending on their hardware and software. Even when it comes to CMYK, there are different colour ranges depending on which global region you are in.

Device-dependent differences

Device-dependent differences are a result of the type of RGB or CMYK profile (as they are often called), which are defined by the camera, scanner, monitor, printer, paper etc. on which the colours are viewed. To ensure consistent colour representation across devices, it’s important to use colour management tools and to create device-independent content. This can involve using standardised colour spaces, such as sRGB or Adobe RGB, and calibrating devices to ensure that they are accurately displaying colours.

LAB

Thankfully there is a parent device-independent colour space. It’s this default colour mode that all devices and software facilitating colour management refer to. This is known as LAB.

When talking about LAB, L represents lightness or brightness, A represents the red-green axis, and B represents the yellow-blue axis. Because LAB is device-independent, you can use it to achieve exact colour matches from one device-specific colour space to another. For example, if you have an image that was created on a digital camera with a specific colour profile and you want to print it, you can use the LAB colour space to convert the colours in the image to the colour profile of the printer. When colour managing, the equation is simple:

LAB + device-dependent colour space = unique colour profile

Professional designers incorporate this into their workflow to produce ‘true’ colours. As part of a business’ colour management policy, these profiles can be added to a designer’s computer monitor and to print press workflows. Different papers can also have their own unique profiles that are also worked into the print workflow. You can even make profiles for projectors!

International standards

Furthermore, we shouldn’t forget about international standards. The most famous and widely used is probably the Pantone Matching System (PMS). This is a proprietary colour space used in a variety of industries that supports the management of colour from design to production. This is largely considered the frame of reference for colour.

In conclusion

The difference between the RGB and CMYK colour spaces is an essential aspect of colour management in the design industry. While CMYK is used for traditional print, the RGB colour space is used for screen-based media. This is thus the main reason why colours look different depending on the format. Furthermore, there are other device-dependent differences which occur due to the type of RGB or CMYK profile defined by the camera, scanner, monitor, printer, or paper on which the colours are viewed. So, to ensure colour consistency across devices, colour management tools should be used, as well as creating device-independent content in standardised colour spaces. Overall, understanding the different colour spaces and profiles is crucial to ensure consistent and accurate colour representation in design projects.

Work with us

As you can see, there is a lot more to colour than meets the eye. If you need expert help, Dusted is here for you. We are brand specialists providing, among other services, design solutions to world-renowned clients across tech, finance and professional services.

At Dusted, we are committed to raising the bar by offering high-quality products that maximise your chances of success.