Colour Blindness Simulator
Simulate 8 types of colour vision deficiency on any image. Side-by-side and grid comparison views. Colour palette checker identifies indistinguishable colours. Based on scientifically accurate Machado et al. 2009 matrices. Free. No sign-up. Images never leave your device.
Drop an image, click to upload, or paste from clipboard
Supports JPEG, PNG, WebP. Files never leave your device.
Colour Vision Deficiency: Key Facts
Approximately 1 in 12 men have some form of red-green colour vision deficiency.
About 1 in 200 women have red-green CVD due to X-linked recessive inheritance.
Over 300 million people globally live with some form of colour vision deficiency.
Deuteranomaly (weak green) is the most prevalent type, affecting about 5% of all males.
| Type | Category | Prevalence | Affected Colours |
|---|---|---|---|
| Protanopia | Red-blind | ~1.3% of males | No red cones — red appears dark |
| Deuteranopia | Green-blind | ~1.2% of males | No green cones — green-red confusion |
| Tritanopia | Blue-blind | ~0.001% of population | No blue cones — blue-yellow confusion |
| Protanomaly | Red-blind | ~1.3% of males | Weak red cones — reduced red sensitivity |
| Deuteranomaly | Green-blind | ~5% of males | Weak green cones — most common type |
| Tritanomaly | Blue-blind | ~0.01% of population | Weak blue cones — rare |
| Achromatopsia | Monochromacy | ~0.003% of population | Total colour blindness — greyscale only |
How it works
- 1Upload an image
Drag and drop, click to browse, paste from clipboard, or load from a URL. All processing happens in your browser — nothing leaves your device.
- 2Choose a simulation type
Select from 8 CVD types: protanopia, deuteranopia, tritanopia, protanomaly, deuteranomaly, tritanomaly, achromatopsia, or view all at once in grid mode.
- 3Analyse and fix
Compare original vs. simulated side by side, check your colour palette for indistinguishable pairs, and download the simulated image for documentation.
Why Test Your Designs for Colour Blindness
Approximately 300 million people worldwide live with some form of colour vision deficiency. For web designers, app developers, and content creators, this means that colour alone should never be the only way to convey information. Graphs that distinguish data series solely by red vs. green, error messages that rely on colour without icons, and navigation systems that use colour-coded labels without text alternatives all create barriers for a significant portion of your audience.
This simulator uses scientifically accurate colour transformation matrices based on the Machado, Oliveira, and Fernandes (2009) research to replicate how images appear to people with each of the eight major types of colour vision deficiency. The matrices transform pixel data in linearised sRGB colour space to produce accurate simulations of protanopia, deuteranopia, tritanopia, and their anomalous (partial) variants, as well as achromatopsia (complete colour blindness).
The side-by-side comparison view lets you evaluate one CVD type at a time against the original, while the grid view shows all eight simultaneously in a compact layout. This dual-view approach is essential for identifying which specific deficiency types your design struggles with. The colour palette checker takes accessibility testing further by letting you input your brand or UI colours and immediately seeing which pairs become indistinguishable under each CVD type.
Web Content Accessibility Guidelines (WCAG 2.1) require that colour is not the sole means of conveying information (criterion 1.4.1). Testing your designs through this simulator helps you meet that requirement and build products that work for everyone. All processing happens in your browser — your images are never uploaded or stored.