Color Blindness Simulator

What is it?

Color blindness (more accurately called color vision deficiency, or CVD) affects approximately 8% of males and 0.5% of females worldwide — roughly 300 million people. Contrary to popular belief, most people with CVD do not see in black and white; they experience a reduced ability to distinguish certain colors, particularly red-green distinctions. This simulator applies mathematically derived transformation matrices to every pixel of your image, replicating how the visual cortex processes color information under each type of CVD. The four simulated conditions are: **Protanopia** affects the long-wavelength (red) cone cells. Reds appear dark or black; red-green distinctions are lost. About 1% of males are affected. **Deuteranopia** affects the medium-wavelength (green) cone cells, causing similar red-green confusion to protanopia but with subtly different color shifts. It is the most common form of CVD, affecting about 1% of males. **Tritanopia** affects the short-wavelength (blue) cone cells. Blues appear green; yellows appear violet. It is rare, affecting about 0.003% of the population. **Achromatopsia** is complete color blindness — the absence of all cone function. Affected individuals see only in grayscale and have extreme light sensitivity. The transformation matrices used in this tool are based on the peer-reviewed research by Gustavo Machado, Manuel Oliveira and Leandro Fernandes, published in IEEE Transactions on Visualization and Computer Graphics (2009), which is the most widely cited algorithm for perceptually accurate CVD simulation.

How to use it

1. Click the upload area or drag and drop an image (PNG, JPG, WEBP) into the tool.
2. Select the type of color vision deficiency from the buttons: Protanopia, Deuteranopia, Tritanopia or Achromatopsia.
3. The simulated image appears side by side with the original — compare them directly.
4. Switch between types to compare different simulations instantly.
5. Click "Download Simulated Image" to save the result as a PNG file.

Why use this tool

Designers and developers use this simulator to verify that their UI, infographics, data visualizations, maps and marketing materials are accessible to people with CVD. If key information in your design relies solely on red-green color distinctions, a large portion of your audience may miss it. Web Content Accessibility Guidelines (WCAG) 2.1 require that color is not the only means of conveying information (Success Criterion 1.4.1). Checking your designs through a CVD simulator is the fastest way to spot accessibility failures before shipping. The tool is equally useful for photography and video production — understanding how your color grading appears to CVD viewers helps you make inclusive creative decisions. Product managers and UX researchers also use it to build empathy during accessibility audits. All image processing is done locally using the browser Canvas API. Your image is never uploaded. There is no account required, no watermark added and no file size limit beyond what your browser can handle.

Frequently asked questions