Color blindness simulator
See an image the way people with protan, deutan, tritan or total color blindness see it
Your files stay with you. Conversion happens inside the browser; no file is ever uploaded to a server.
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How it works
Tap or click the box, choose one or more images and tap "Simulate". The default "All four" setting gives you four files per image: red-blind, green-blind, blue-yellow blind and total color blindness. Example: a sales chart shows a dark red (#CC0000) "loss" bar next to a green (#009900) "profit" bar. In the green-blind version the first becomes RGB 130, 114, 0 and the second RGB 143, 128, 31 — both the same mustard shade, impossible to tell apart. That tells you the bars need a label or a pattern, not just a color. With severity on "Full" the cone type is treated as missing; "Moderate" and "Mild" show color weakness instead. Transparent areas stay transparent. Everything runs in your browser and nothing is uploaded.
This tool is also known as color blindness simulator, color blind simulator upload image, colorblind filter for images, how do color blind people see, deuteranopia simulator, protanopia simulator.
What is Color blindness?
Color blindness (color vision deficiency) means one of the three cone types in the retina — sensitive to long, medium or short wavelengths — is missing or shifted. Most people with it still see color; they confuse certain pairs, most often red and green. It is usually inherited and far more common in men than in women. Only an eye doctor can diagnose it; this page only shows what an image looks like.
What is Protanopia, deuteranopia, tritanopia?
The names tell you which cone is not working: in protanopia the long-wavelength (red) cone, in deuteranopia the medium-wavelength (green) cone, in tritanopia the short-wavelength (blue) cone. If the cone is present but shifted, the name ends in "-anomaly" (deuteranomaly, for example) and colors merge only partly — the "Moderate" and "Mild" severity settings show that case.
Is a color blindness simulation the same as grayscale?
No. Grayscale removes all color, which matches only total color blindness (achromatopsia), and that is rare. Most color blind people do see color but mix up specific pairs: with green blindness, red and green both turn yellowish brown while blue stays blue. Checking a design in grayscale alone therefore misses the red-green confusion that causes most real problems; only a simulation like this one shows it.
What the simulation can and cannot show
The result is a prediction from the physiological model Machado and colleagues published in 2009: it calculates where colors shift for an average person with each deficiency. Real people vary, and two people with the same diagnosis do not see an image identically. For blue-yellow (tritan) deficiency the model is a rougher approximation than for the red-green types.
Your screen's brightness and color settings also affect what you see. Showing the result to a color blind person shows them nothing new. The tool is for empathy and design checks; it does not diagnose or correct color blindness.
Found a problem? How to fix it
Start with "All four"; most problems show up in the red-green types. If two items differ only by color and turn into the same shade in the simulation, add a second cue: write values or names on chart bars, use solid and dashed lines, add patterns or labels on maps.
If you change colors, pick a pair that also differs in lightness, such as orange and blue — lightness differences survive every type. For text on a background, also measure the WCAG contrast ratio with the color contrast checker on this site.
Frequently asked questions
How do color blind people see a picture?
It depends on the type. With the most common red-green types, reds, oranges and greens move toward a yellowish brown while blues and purples stay distinct. Upload your own image here to see all four types side by side.
Is this a color blindness test?
No. This page does not measure your color vision; it shows how an image looks to someone with color blindness. For a diagnosis, see an eye doctor.
Which type should I pick?
If you are unsure, choose "All four". The red-green types (red-blind and green-blind) are the most common, so a design that reads well in those two works for most people.
Is my image uploaded to a server?
No. The calculation runs in your browser on the image's pixels; the file never leaves your device. Once the page is open it keeps working even offline.