Colorblind Simulator
See an approximation of how your image looks with protanopia, deuteranopia, tritanopia, the milder anomalies or achromatopsia, based on a published simulation model.
Red
Green
Blue
Yellow
Orange
Purple
Cyan
Pink
Left: Original | Right: Simulated
Drop your image here
Choose an image to simulate how it appears with color blindness
Max 1 file, up to 50.0 MB each
About the Colorblind Simulator
Roughly one in twelve men and one in two hundred women have some form of color vision deficiency, most often difficulty telling reds and greens apart. That matters whenever color alone carries meaning: red and green status labels, lines in a chart, map legends, error states in a form. This simulator transforms the colors of your image to approximate how it may look with seven types of color vision deficiency, so you can spot information that disappears.
How it works: each pixel is converted to linear RGB, multiplied by a 3×3 color transformation matrix from the model published by Machado, Oliveira and Fernandes in 2009, and converted back. The three “-anopia” types (protanopia, deuteranopia and tritanopia) use the model at full severity. The three “-anomaly” types use a moderate severity of 0.6, although real anomalous color vision ranges from very mild to nearly complete. Achromatopsia is shown as grayscale based on luminance.
Treat the output as an approximation. Vision varies from person to person, screens differ, and no matrix can show exactly what someone else sees. What a simulation is good at is revealing problems: if two lines in your chart turn into the same muddy shade under deuteranopia, many readers with that condition will struggle too. The fix is usually an extra cue rather than a different hue: labels, patterns, icons or a clear difference in lightness.
The comparison strip shows eight basic colors before and after for the selected type, even before you upload anything. To check text legibility with numbers, use the Contrast Checker; to build and refine a palette, try the Color Palette Generator.
How to use the Colorblind Simulator
- 1
Choose a type
Select one of the seven options under Type of Color Blindness. The comparison swatches update straight away.
- 2
Add an image
Drop a screenshot, chart or photo (JPG, PNG, WebP, GIF or BMP) onto the drop area or click Browse Files.
- 3
Compare
The simulated version appears next to the original. Untick Show side by side for a larger single view, and switch types to compare them.
- 4
Download
Click Download Simulated Image to save the result as a PNG.
What it can do
Seven simulations
Protanopia, deuteranopia, tritanopia, protanomaly, deuteranomaly, tritanomaly and achromatopsia.
Published model
Matrices from Machado et al. (2009), applied in linear RGB rather than directly to gamma-encoded values.
Instant switching
Choosing another type re-processes the selected image automatically.
Color swatch comparison
Red, green, blue, yellow, orange, purple, cyan and pink shown before and after.
Transparency kept
Alpha values are left untouched and the result is saved as PNG.
Limitations
- The result is an approximation; it can’t show exactly what any individual sees, and it depends on your screen.
- The anomaly types use one fixed severity (0.6), so mild and severe cases are not shown separately.
- Only still images are supported. To test a web page or video, take a screenshot first.
- Large images take longer and need more memory, because every pixel is processed in the browser.
Privacy
The image is processed pixel by pixel in your browser and is never uploaded to FlexyPdf’s servers.
Frequently asked questions
How accurate is the simulation?
It uses a published, widely used physiological model, which makes it a reasonable approximation for finding problems in a design. It is not a diagnostic tool and can’t show exactly what a particular person sees.
Which type should I test first?
Start with deuteranomaly and deuteranopia, then protanopia, because red-green deficiencies are by far the most common. Tritanopia is rare but worth a quick check if your design relies on blue and yellow.
How do I test a website?
Take a screenshot of the page, or of the chart or form you care about, and upload it. The tool works on images, not on live pages.
Two colors in my chart look identical in the simulation. What now?
Add a second way to tell them apart: direct labels on the lines, different line styles or markers, or colors that also differ clearly in lightness. Then check again with the simulator.
Does color blindness mean seeing in black and white?
Rarely. Most people with a color vision deficiency see colors but confuse certain hues. Complete color blindness (achromatopsia) is very rare.
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