Color Blind Filter

How the color blind filter works

A color blind filter re-maps the colors in a photo or live camera view so pairs you normally confuse become easier to tell apart. This free tool uses daltonization — the color science also behind color blindness glasses — tuned to your type (protan, deutan, or tritan), and runs entirely in your phone's browser: point the camera, compare before and after, save the result. It helps you distinguish colors; it does not cure color blindness or show you what typical color vision looks like. A third mode reverses the direction: Simulate shows a normally-sighted viewer what any scene or image looks like with a chosen deficiency, at any severity.

Simulate color blindness — for designers, developers & teachers

A color blindness simulator transforms an image or live camera view to show what someone with a color vision deficiency actually sees, so designers, developers, and teachers can spot color combinations that fail color-blind viewers. This tool uses the Machado, Oliveira & Fernandes (2009) physiologically-based model — the current academic standard — and simulates protan, deutan, and tritan deficiencies at any severity, from mild anomalous trichromacy to complete dichromacy. That matters because most real-world color vision deficiency is partial: simulators that only show the complete forms overstate the effect and can mislead accessibility decisions. Everything runs in your browser; nothing is uploaded.

Switch the tool above to Simulate, pick a type, and drag the severity slider. Reference: Machado, G. M., Oliveira, M. M., & Fernandes, L. A. F. (2009). A Physiologically-based Model for Simulation of Color Vision Deficiency. IEEE Transactions on Visualization and Computer Graphics, 15(6), 1291–1298.

Working from a file rather than a camera? The color blindness simulator takes an upload or a built-in test scene, puts the original and the simulation side by side behind a draggable divider, and exports the frame with its severity stamped on it — the same engine, built for design review instead of live vision.

What does it look like to be color blind?

Mostly like normal vision, with certain color differences shrunk or gone — not a gray world. The strips below are computed with the same Machado 2009 model the simulator uses: the top row is the original palette, the rows beneath show how the same colors look with each complete deficiency, and the last row shows a moderate (50%) deutan — the kind of partial deficiency most color-blind people actually have. Notice how red and green collapse toward each other for deutan and protan viewers, while blue and yellow survive; tritan does the reverse.

To see any scene or your own images this way — at any severity, not just these anchors — switch the tool above to Simulate mode.

Color blind filter — frequently asked questions

What is a color blind filter?

A color blind filter is a color transformation that re-maps the colors a color vision deficient person confuses into colors they can distinguish. The standard technique is called daltonization: software estimates which color differences are invisible to your type of deficiency, then shifts that lost difference into hues you can still see. The result looks recolored — and that is the point.

How does daltonization work?

Daltonization works in three steps. First it simulates how a scene looks to your type of color vision deficiency (using the Machado 2009 simulation model). Second it computes the error — the color information you lose. Third it re-injects that error into the channels you do see: for red-green types the lost red-green difference is pushed into blue and brightness; for blue-yellow (tritan) types it is pushed toward red-green. This tool applies all three steps as one transformation, in real time on the camera.

Does a color blind filter fix color blindness?

No. Color blindness is caused by the cone cells in your retina, and no filter, app, or pair of glasses changes that. A filter helps you distinguish colors in a specific image by deliberately changing them — useful for telling things apart, but the colors you see are shifted, not 'corrected', and the effect ends when you stop looking through it.

Can this filter help me read an Ishihara test plate?

It can make the hidden figure easier to see. Switch to “Read plate” mode: instead of the gentle everyday re-mapping, it strongly exaggerates the single color axis a plate hides its figure along — red-green plates are pushed toward blue-yellow, blue-yellow plates toward red-green — so the number or shape stands out. Pseudo-isochromatic plates are deliberately designed to resist color cues, so how well it works depends on the plate and the strength of your deficiency; raise the strength slider for the biggest effect. Reading a plate through a filter is an accessibility aid, not a substitute for taking the test under normal conditions.

What is a color blindness simulator?

A color blindness simulator shows people with typical color vision what an image or scene looks like to someone with a color vision deficiency. Designers and developers use it to check that charts, maps, UI states, and teaching materials still work when red-green or blue-yellow differences disappear. The Simulate mode in this tool applies the Machado, Oliveira & Fernandes (2009) physiologically-based model — the peer-reviewed standard for CVD simulation — to your live camera or any photo, entirely on your device.

How is this simulator different from other online color blindness simulators?

Two ways. First, severity is continuous: most online simulators only show complete dichromacy (protanopia, deuteranopia, tritanopia), but the large majority of color-blind people have partial deficiencies — anomalous trichromacy — so complete-only simulation exaggerates what most real viewers experience. This tool simulates any severity from mild to complete, using the interpolation the Machado 2009 paper itself endorses. Second, it works on a live camera as well as photos, so you can point it at a printed poster, a projected slide, or a room, not just an uploaded file.

Does my screen affect what the simulator shows?

Yes, and it is worth knowing why. Every display has its own color temperature, white point, and gamut, so an identical simulated image renders differently on a phone, a laptop, and a calibrated studio monitor — and none of them is the single correct rendering. Two practical consequences: judge a palette by sweeping the severity slider and checking whether it survives the whole range, rather than trusting one frame at one setting; and confirm anything safety-critical on the medium it will actually be viewed on. The model simulates the eye, not your monitor.

Is this a free alternative to the Coblis color blindness simulator?

It covers the same job — showing what an image looks like with a color vision deficiency — with two technical differences. Coblis uses the HCIRN/Wickline simulation function from the early 2000s and offers the complete forms plus monochromacy; this tool uses the Machado, Oliveira & Fernandes (2009) model, the current peer-reviewed standard, with a continuous severity slider that also covers the partial deficiencies most color-blind people actually have. It also works on a live camera, not just uploaded files. Coblis remains a fine tool for quick complete-form previews; for accessibility decisions, severity control matters because complete-only simulation overstates what most real viewers experience.

Is this the same as color blindness glasses?

It's the same goal by a different mechanism. Color blindness glasses use optical notch filters that cut the wavelengths where red and green signals overlap, which can increase contrast for some red-green deficiencies. A digital filter can go further: it knows your type and severity, works for tritan as well, and can re-map colors arbitrarily rather than only subtracting light. Neither glasses nor filters provide typical color vision.

Are my photos uploaded anywhere?

No. The camera stream and your photos are processed entirely on your device using WebGL in the browser. Nothing is uploaded, stored, or sent to a server, and no account is needed.

Which type should I choose if I don't know mine?

Deutan (green-weak) is the most common type, so it's the best first guess — about 6% of men. But the better answer is to take the free 2-minute color vision test on this site: it estimates your type and severity, and the filter then tunes itself to your result automatically.

Why doesn't the live camera work in WeChat or Instagram?

In-app browsers often block the camera API (getUserMedia) that the live filter needs. If that happens, this tool automatically falls back to photo mode — take a photo with your normal camera button and the same filter is applied. For the live experience, open the page in Safari or Chrome directly.