No upload, 100% local, no account

Color Blindness Simulator

See your image through the eyes of someone with a color vision deficiency. Choose the type, preview and download the result. Everything runs in your browser.

How Color blindness simulator works

Color blindness simulator applies a scientifically derived color transformation to an image to show how it appears to people with protanopia (red-blind), deuteranopia (green-blind), tritanopia (blue-blind) or achromatopsia (no color perception). Designers use it to audit charts, maps, infographics and UI screenshots for accessibility before publishing.

Unlike Color palette (which extracts dominant colors) and Color scheme (which generates palettes), this tool transforms an entire image to simulate a different perceptual experience. It uses established linear-algebra colour matrices from peer-reviewed models, a close perceptual approximation rather than a medical diagnostic, accurate enough to catch problematic colour combinations.

Frequently asked questions

Are my files uploaded to a server?

No. Your image is processed by the HTML5 Canvas API in your browser tab, its pixels are read with getImageData, a colour-vision matrix is applied, and written back with putImageData, and the result is offered as a local download. Nothing reaches Sunasty or any third party. Open your browser's DevTools, go to the Network tab and watch: no request carries your image.

Which types of color vision deficiency does it simulate?

It simulates protanopia (insensitivity to red, ~1% of males), deuteranopia (insensitivity to green, ~1% of males), tritanopia (insensitivity to blue, rare) and achromatopsia (complete absence of color vision, very rare). Protanopia and deuteranopia together cover most real-world color blindness cases.

How accurate is the simulation?

It uses established linear-algebra color matrices derived from peer-reviewed models of color vision deficiency. The result is a close perceptual approximation, not a medical diagnostic tool, and is accurate enough to catch problematic color combinations in a design.

Does it work offline?

Yes, once the page has loaded. Because the processing happens on your device, you can disconnect from the network and the tool keeps working. This is the clearest proof that your data never leaves your machine.

Is it free? Do I need an account?

It is completely free and requires no sign-up. There are no watermarks, no daily limits and no tracking cookies needed to use the tool.