Guides JP

Color Blindness Simulator

Load an image to simulate how it appears to people with protanopia, deuteranopia, tritanopia, or achromatopsia, and compare it side by side with the original. Verify your color choices are accessible to everyone. All processing happens in your browser and images are never uploaded.

Last updated: 2026/10/18 Design Feedback & bug reports

Drag & drop

or

CtrlV Ctrl+V to paste a screenshot

JPEG, PNG, WebP, GIF, HEIC (iPhone) / max 20MB

Vision Type
100%
0% = normal vision, 100% = full dichromacy (strongest)
View

How to Use

1

Load an Image

Drag & drop, click to select, or paste a screenshot with Ctrl+V.

2

Choose Type & Severity

Pick protanopia, deuteranopia, tritanopia, or achromatopsia and adjust the severity slider.

3

Compare & Save

Compare side by side with the original and download or copy the result.

About the Color Blindness Simulator

An online tool that loads an image and reproduces how it appears to people with color vision deficiencies. Using the color vision transformation matrices by Machado et al. (2009), it accurately simulates protanopia, deuteranopia, tritanopia, and achromatopsia at adjustable severity levels. It is ideal for accessibility checks of web designs, documents, charts, and UI color schemes. All processing happens locally in your browser and your images are never uploaded to any server.

Features

  • 4 Vision TypesSimulate protanopia, deuteranopia, tritanopia, and achromatopsia (monochrome).
  • Adjustable SeverityUse the slider to vary from mild color weakness to strong color blindness.
  • Side-by-Side CompareCompare the original with the result, or view all types at a glance.
  • Browser-Only ProcessingAll processing happens locally. Your images are never uploaded to any server.

Use Cases

  • Accessibility check of UI color schemes in websites and apps
  • Verify charts and graphs do not rely on color alone
  • Validate color usage in documents, slides, and posters
  • Check readability of transit maps and signage
  • Color universal design education and awareness

FAQ

Are my images uploaded to a server?
No. All processing happens in your browser. Your image data is never sent to any server.
How accurate is the simulation?
It uses the color vision transformation matrices published by Machado et al. (2009), a widely cited academic method. Actual perception varies between individuals, so use it as a design aid rather than a medical reference.
What are protanopia, deuteranopia, and tritanopia?
Protan affects red-sensitive cones, Deutan affects green-sensitive cones, and Tritan affects blue-sensitive cones. Protan and Deutan types are the most common.
What does the severity slider change?
It changes the severity of the condition. 0% is normal vision; higher values move continuously from mild color weakness to strong deficiency (full dichromacy at 100%).
What formats and sizes are supported?
JPEG, PNG, WebP, GIF, and HEIC (iPhone photos) up to 20MB. Very large images may take longer to process.
Does it work on mobile?
Yes. It works in browsers on smartphones, tablets, and PCs.

Related Tools

px to vw Converter Convert CSS px to vw. Bulk CSS conversion supported px to em/rem Converter Convert CSS px to em/rem. Bulk CSS conversion supported Aspect Ratio Calculator Calculate simplified aspect ratio from dimensions Line Height Calculator Calculate line-height ratio from font size and leading CSS Gradient Generator Visually create Linear, Radial & Conic CSS gradients

Popular Tools

Character Counter Count characters, words, and lines in real-time JSON Formatter Format and validate JSON with syntax highlighting QR Code Generator Create custom QR codes with logo, colors & styles Password Generator Generate secure random passwords with one click Base64 Encoder Encode and decode text or files to Base64 IP Address Checker Check your global IP address

Related Guides

Color Contrast Ratio and Accessibility: WCAG Levels, Relative Luminance, and Readable Palettes Learn color contrast and accessibility from the ground up: the WCAG thresholds (4.5:1, 3:1 for large text, 7:1 for AAA), how relative luminance works, why contrast matters, designing for color vision diversity, and how to build palettes everyone can read.