What types of colour blindness does this tool simulate?
Four major categories: Protanopia (missing red cones, ~1% of men), Deuteranopia (missing green cones, ~1% of men — the most common form), Tritanopia (missing blue cones, very rare), and Achromatopsia (no colour vision, monochrome). Together these cover roughly 8% of men and 0.5% of women worldwide. We apply clinically-derived LMS colour-space matrices used in academic vision research.
How accurate is a browser-based CVD simulator?
The maths is accurate for dichromacy (complete absence of one cone type). Real-world CVD is more often anomalous trichromacy — a shifted cone, not a missing one — which produces milder symptoms than our filters show. Use the simulator as a worst-case audit: if your design is readable through Deuteranopia, it is comfortable for the much larger anomalous-trichromat population.
Can I use my webcam for live CVD simulation?
Yes. Click the camera option and grant permission — every frame is filtered in real time using a WebGL shader. This is useful for checking physical objects (UI mockups on paper, signage, product packaging). The webcam stream stays on your device; nothing is uploaded. Requires HTTPS and a working camera, of course.
Why do reds and greens look identical in some filters?
Because that is exactly what Protanopes and Deuteranopes experience. Red and green wavelengths fall on the same remaining cone type, so a stoplight, a heatmap, or red-on-green error text becomes ambiguous. The fix is not to avoid those colours but to add a second channel of information: shape, position, labels, or luminance contrast.
What contrast ratios should I aim for alongside CVD checks?
WCAG 2.2 requires 4.5:1 contrast for normal body text and 3:1 for large text and UI components. CVD simulation does not replace contrast checking — a Deuteranope still needs the same luminance contrast as anyone else. Use this tool together with a contrast checker for a complete accessibility pass.
What other accessibility-adjacent tools are available?
Our Sensors motion test helps audit reduced-motion preferences and vestibular triggers. The Multi-touch tool reveals whether interactive targets are reachable by users with limited dexterity. The CPU benchmark exposes whether your site stays responsive on low-end devices favoured by users with accessibility needs.