Free color blindness simulator: upload any photo and preview it as people with protanopia, deuteranopia, tritanopia or total color blindness see it, right in your browser.
About 1 in 12 men and 1 in 200 women in the world live with some form of color blindness. They do not see the world in black and white. They see it differently: reds can look like greens, blues can melt into greens, and some color pairs that look obvious to you can be impossible to tell apart for them. If you design graphics, pick chart colors, teach children, or share photos online, that difference matters. Our free color blindness simulator lets you upload any image and preview it exactly the way people with different types of color vision see it.
The tool runs fully in your browser. Your photo is never uploaded to a server, never stored, and never seen by anyone else. You pick an image from your device, choose a vision type, and the preview updates.
What color blindness really is
Color vision comes from three types of cone cells in the eye, sensitive to red, green, and blue light. Color blindness happens when one type of cone works differently or is missing. The most common forms are red-green problems: protanopia, where the red cones are missing, and deuteranopia, where the green cones are missing. Both make reds and greens hard to separate. Tritanopia is rarer: the blue cones are missing, so blues and greens blur together and yellows can look pink. Achromatopsia, total color blindness, is very rare and leaves only shades of gray.
Most people with color blindness still see plenty of color. What they lose is the difference between specific pairs. A red traffic light and a green one can look alike. A red error message on a green background can vanish. A chart that uses red and green lines to show profit and loss can become unreadable. That is why checking your images matters: problems that are invisible to you are obvious once you simulate them.
How the simulator works
The tool reads every pixel of your photo and applies a published color-vision-deficiency matrix to its red, green, and blue values. These matrices come from vision research and describe, in numbers, how each type of color blindness shifts colors. A red pixel under protanopia, for example, becomes a darker, browner tone. The result is not a filter or a guess. It is a mathematical model of how the eye responds, applied pixel by pixel, in real time.
Because all of this runs on your own device, even large photos process fast, and nothing leaves your browser. There is no account, no upload queue, and no waiting. The simulation is an approximation, not a medical test: real color vision varies from person to person. But for design decisions, teaching, and checking your own work, it is the standard approach used by accessibility professionals.
Who should use it
Graphic designers use it to check logos, posters, and social media images before publishing. If your call-to-action button only stands out because it is red on a green background, a large part of your audience will miss it. Data analysts use it to check charts and maps: a heat map that goes from red to green is one of the worst choices you can make, and the simulator shows you why in seconds. Teachers use it to show students what a classmate sees, which builds understanding far better than any explanation.
Photographers use it to check whether the mood of a photo survives for color blind viewers. Web developers use it to test site screenshots before launch. If you ever wondered whether your work is readable for everyone, this tool gives you the answer in one click.
How to use the simulator
First, click the upload button and choose a photo from your device. Any common format works: JPEG, PNG, WebP, or GIF. Second, pick a vision type from the menu: normal vision for comparison, protanopia, deuteranopia, tritanopia, or achromatopsia. The preview updates instantly. Third, if you want to keep the result, click the download button to save the simulated image as a PNG. Try the same photo under each vision type. You will be surprised how different the same image can look.
Simple rules for color blind friendly images
Once you have seen the simulation, a few habits will make your images work for everyone. Never use color alone to carry meaning: pair it with labels, icons, patterns, or different brightness. A red circle and a green circle can look identical, but a red circle with an X and a green circle with a checkmark never will. Choose color pairs that differ in brightness, not just hue: dark blue and bright yellow survive almost every form of color blindness. Avoid red-green and blue-green combinations for critical information. And always run your final image through the simulator before you publish. It takes ten seconds and it can save your message.
Frequently asked questions
Is this a medical test for color blindness? No. It simulates how images look under different types of color vision. It cannot diagnose anything. If you think you may be color blind, see an eye specialist for a proper test.
Is my photo private? Yes. The tool runs entirely in your browser. Your image never travels over the internet, is never stored on our servers, and is never seen by anyone but you.
Color blindness affects hundreds of millions of people. Upload a photo now and see it through someone else’s eyes.
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- Versión en español
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