Colour plays a vital role in digital design, from creating visual appeal to guiding users through interfaces. But for the millions of people with colour blindness, certain design choices can create barriers to accessibility. Colour blindness, or colour vision deficiency (CVD), affects around 1 in 12 men and 1 in 200 women globally. Designing with these users in mind is essential to ensuring that everyone can engage with digital content effectively.

In this post, we’ll explore what colour blindness is, how it impacts users’ experiences with digital interfaces, and practical strategies to design in a way that accommodates individuals with CVD.

What is Colour Blindness?

Colour blindness refers to a range of conditions where a person’s ability to perceive certain colours is reduced or absent. The most common form of colour blindness is red-green colour deficiency, where individuals have difficulty distinguishing between shades of red and green. Less common types include blue-yellow deficiency and complete colour blindness, where all colours are seen in shades of grey.

For those with CVD, digital designs that rely heavily on specific colour contrasts may not be fully accessible. This can make tasks like reading text, interpreting graphs, or navigating interfaces more difficult, especially when key information is conveyed through colour alone.

Real-World Impact of Colour Blindness

Imagine using a website where buttons for "submit" and "cancel" are only differentiated by colour — say, red for cancel and green for submit. For someone with red-green colour blindness, these buttons may appear nearly identical, increasing the risk of errors. Similarly, data visualisations that use only colour to distinguish between categories can be hard to interpret, making it challenging for users with CVD to grasp the information.

By understanding these challenges, we can take steps to ensure digital designs are accessible to everyone, including those with colour blindness.

Red and green toggle switches highlighting challenges for colourblind users in distinguishing between these colors.

Design Challenges for People with Colour Blindness

Colour blindness can affect users in a variety of ways when engaging with digital interfaces. Here are some common design challenges that people with CVD might face:

1. Insufficient Colour Contrast

Red, blue, yellow, and dark green shapes illustrating challenges in colour contrast for users with colour blindness.

Low contrast between text and background colours is one of the biggest issues for users with colour blindness. If the contrast is too subtle, people with CVD may struggle to read the content or may miss important information altogether. This is particularly problematic on websites with light-coloured text on pastel or light backgrounds, or with dark-coloured text on dark backgrounds.

2. Colour-Dependent Navigation

Design elements that rely solely on colour to convey meaning can be confusing for people with CVD. For example, if hyperlinks are only distinguished by being blue, or if important notifications are only indicated by a red box, these cues might be missed by those who can’t easily distinguish these colours.

3. Inaccessible Data Visualisations

Infographic template using various shades of red to demonstrate the issue of inaccessible data visualisations for users with colour blindness, particularly when only colour is used to distinguish data points.

Charts, graphs, and infographics that use only colour to differentiate between data points can exclude users with CVD. A pie chart with several shades of green and red can appear nearly indistinguishable to someone with red-green colour blindness, making it hard to interpret the information correctly.

Best Practices for Designing for Colour Blindness

Creating accessible designs for users with colour blindness doesn’t require sacrificing creativity. By following a few key principles, designers can make their interfaces more inclusive without compromising visual appeal.

1. Use High Colour Contrast

Retail website example demonstrating the importance of using high contrast between text and background to ensure legibility for all users, especially those with visual impairments.

Ensure sufficient contrast between text and background colours to make content legible for everyone. Aim for a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text, as recommended by the Web Content Accessibility Guidelines (WCAG). Tools like contrast checkers can help designers evaluate whether their colour choices meet these guidelines.

Example: A retail website can enhance contrast by using dark text on a light background or vice versa, ensuring that product descriptions are easy to read for all users.

2. Avoid Relying Solely on Colour

Don’t use colour as the only way to convey meaning or highlight key elements. Combine colour with text labels, patterns, or icons to ensure users with CVD can understand the information.

Example: In a form, use both colour and icons to show errors—like a red outline around a field and a clear error message that says "Please enter your name." This helps users with colour blindness know what needs attention.

3. Choose Colour-Blind Friendly Palettes

Certain colour combinations are more difficult for people with CVD to distinguish. Avoid problematic pairings like red-green, blue-purple, or green-brown. Instead, opt for colour-blind friendly palettes that include high-contrast, easily distinguishable hues.

Example: A data visualisation tool could use a palette with distinct shades of blue, orange, and purple, ensuring that all users can easily differentiate between categories in a graph.

4. Provide Textures and Patterns in Visual Data

In charts and graphs, use patterns, textures, or labels in addition to colour to differentiate between data sets. This makes it easier for users with CVD to interpret the information accurately.

Example: A bar chart showing sales performance could use different textures (like dots, stripes, or crosshatches) for each bar alongside colour, ensuring that data is clear to everyone, regardless of colour perception.

5. Test Designs for Colour Blindness

There are several tools available that simulate how your design will appear to someone with colour blindness. Using tools like Coblis or Colour Oracle can help you ensure that your design works for everyone.

Example: Before launching a new website, a designer can use these tools to check how a colour scheme appears to users with different types of CVD and adjust accordingly to improve accessibility.

The Benefits of Designing for Colour Blindness

When digital designs accommodate users with colour blindness, they benefit everyone. Improved contrast, clearer instructions, and more thoughtful use of colour make for a better user experience overall. Accessible design fosters inclusivity, ensuring that no one is excluded due to visual differences. Moreover, businesses and organisations that prioritise accessibility can reach a wider audience, improving engagement and customer satisfaction.

Inclusive Design is Better Design

Designing with colour blindness in mind is a crucial aspect of creating an accessible, inclusive digital environment. By using high-contrast colour combinations, avoiding reliance on colour alone, and considering alternative ways to present information, designers can ensure their digital spaces are welcoming to all users.

By making small adjustments, we can create a digital world that’s easier to navigate for everyone, regardless of how they perceive colour.

Understanding Colour Blindness in Digital Design