Designing for Colour Vision Deficiency: A Scoping Review of Resources That Support Designers in Choosing Accessible Colours
Connor Geddes, Edward Curran Eggertson, Jonathan Sutton, Garreth W. Tigwell · 2025 · ASSETS 2025: 27th International ACM SIGACCESS Conference on Computers and Accessibility · doi:10.1145/3663547.3746370
Summary
This paper presents a comprehensive scoping review of 113 academic papers focused on design methods that support colour accessibility for people with colour vision deficiency (CVD). CVD affects approximately 1 in 12 men and 1 in 200 women, making certain uses of colour in digital designs inaccessible. The review followed PRISMA-ScR guidelines and searched ACM Digital Library and IEEE Xplore, supplemented by backward and forward reference searching. The 113 papers were categorized into three groups: 46 design tools, 55 guidelines, and 12 simulation algorithms. The analysis examined what features and recommendations these resources provide and how they are evaluated. The authors developed a codebook organized around four core attributes: targeted domain, evaluation data, and whether the strategy was a design tool or guideline. The most commonly targeted domains were web development, data visualization, and video games — areas with heavy reliance on colour for conveying information. The review reveals a significant imbalance in the landscape: most design tools focus on identifying colour problems through CVD simulation (72% of tools) and contrast ratio checking (35%), but far fewer help designers actively generate accessible colour palettes (only 13%) or suggest alternative colour choices. Similarly, guidelines predominantly recommend ensuring high contrast (58%) and proofing with simulations (31%), while practical guidance on implementing redundant encoding or selecting CVD-safe palettes receives less attention.
Key findings
The review identifies several critical gaps in current CVD-accessibility resources. First, design tools overwhelmingly focus on problem identification rather than solution generation — 33 of 46 tools feature CVD simulation, but only 6 offer colour scheme generation. Second, a troubling 22% of design tools and 38% of guidelines included no evaluation at all. Among those evaluated, only 10% of design tool papers and 24% of guideline papers tested with actual CVD users. Third, the popular guideline "don't use colour alone" can inadvertently lead designers to simply re-encode colour information (e.g., using a leaf symbol for green) rather than using truly meaningful redundant encoding. Fourth, current contrast ratio calculations based on WCAG's luminous efficiency function (LEF) do not account for the abnormal LEFs of people with CVD — meaning a colour pair meeting WCAG contrast requirements may still have insufficient contrast for protanopes, for whom reds appear dimmer. The authors propose ten research opportunities including: developing tools that actively assist in selecting accessible colours rather than just flagging problems, creating CVD-specific contrast checkers that account for abnormal luminous efficiency functions, building symbology libraries for secondary coding, and evaluating how CVD simulations actually influence design decisions.
Relevance
This review is essential reading for accessibility practitioners and developers who work with colour in digital design. It exposes a fundamental limitation in current practice: the field has invested heavily in helping designers see what CVD users see (through simulations) but has done far less to help designers fix the problems they find. The finding that WCAG contrast ratios may be insufficient for CVD users is particularly significant for standards compliance work — a design passing WCAG AA contrast requirements could still fail CVD users because the standard observer model does not account for abnormal luminous efficiency. For practitioners, the review validates common guidelines like avoiding colour-only encoding but adds important nuance: redundant encoding must be meaningful and context-appropriate, not merely a symbolic re-encoding of colour. The ten research opportunities provide a roadmap for tool developers and researchers working to improve colour accessibility.
Tags: colour vision deficiency · color blindness · design tools · guidelines · scoping review · colour accessibility · contrast ratio · redundant encoding · CVD simulation
Standards referenced: WCAG 2.1