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Color blindness simulator

This color blindness simulator shows how your chart, logo or photo looks to people with color vision deficiency. Upload an image or compare two colors and see it straight away in four ways of seeing. Calculated in your browser using the model by Machado et al. (2009).

Source: Machado, Oliveira, Fernandes (2009): A Physiologically-based Model for Simulation of Color Vision Deficiency, IEEE TVCG 15(6). Updated: .

Check a color pair

VisionColor 1Color 2ΔE
ΔE = color difference (CIELAB). The smaller the value, the more alike the two colors look.

Drag and drop files here or

One image (JPG, PNG, WebP, HEIC …), up to 50 MB

Tip: you can also paste images with Ctrl + V.

Your files are processed only in your browser and never uploaded – they don’t leave your device.

Simulated image

Choose an image – it will appear here in four ways of seeing.

    My Toolbox

    Result

    How it is calculated

    About 1 in 12 men has a color vision deficiency (National Eye Institute), usually red-green; in women it is much rarer. If you design charts, maps, logos or warning signs, it pays to check that your colors stay distinguishable. This simulator shows images and color pairs the way they are perceived with the most common forms.

    How it works

    1. Check a color pair: pick two colors, such as the red and green of a status chart. The table shows both colors for each type of vision and their difference ΔE.
    2. Check an image: drop an image – it appears as the original and in four simulations side by side.
    3. “Severity” approximates milder forms (anomalies); “Save simulation” downloads the full-size image.

    The model behind it

    The conversion follows the physiologically based model by Machado, Oliveira and Fernandes (IEEE Transactions on Visualization and Computer Graphics, 2009). It describes how the sensitivity of the eye’s cones shifts and gives a 3 × 3 matrix for each type. The matrices work on linear RGB, so colors are first linearised from sRGB (IEC 61966-2-1) and converted back afterwards. Achromatopsia is shown via relative luminance. ΔE is the Euclidean distance in CIELAB.

    Honest limits

    A simulation is an approximation: color perception is individual and screens display color differently. Milder forms are interpolated linearly between normal vision and dichromacy here, while the paper computes separate matrices. The simulator is not an eye test and does not correct color blindness.

    Privacy

    Your image is processed only in your browser and never uploaded.

    Frequently asked questions

    How do color blind people see red and green?

    With protanopia and deuteranopia, red, green and brown blur into similar yellow-olive tones. Pick red and green as the color pair above: the difference ΔE drops sharply for these types.

    Can I upload my own image to the color blindness simulator?

    Yes. Drop a photo, screenshot or graphic into the box. It is converted only in your browser and never uploaded.

    What is the difference between protanopia, deuteranopia and tritanopia?

    Protanopia lacks the red-sensitive cones, deuteranopia the green-sensitive ones and tritanopia the blue-sensitive ones. The first two are the common red-green deficiency; the third is rare.

    How do I choose colors that color blind people can tell apart?

    Combine colors with clearly different lightness, such as dark blue and orange, and add shapes, patterns or labels in addition to color. Check your pair here in every type of vision.

    Can the simulator correct color blindness?

    No. It only shows roughly how colors look with a color vision deficiency. A diagnosis comes from an eye doctor.

    Sources and legal basis

    As of:

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