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With the free Color Blindness Simulator, you can see how your color palette and images appear to people with protanopia (red blindness), deuteranopia (green blindness), deuteranomaly (reduced green sensitivity), tritanopia (blue blindness) or achromatopsia, with all five variants side by side. No sign-up: Colors and images are processed only in your browser and never uploaded.
Built by Justin Schuessler
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Calculated instantly for all simulated variants below. Select a color from your palette below to edit it here.
Click a color to edit it in the picker above. Use the plus button to add more colors and view your entire palette in every simulated variant at once.
Want to check whether your palette has enough contrast too? Also check your simulated palette for contrast
Continue with the selected color: Open in Color Picker · Generate color scheme
Runs entirely in your browser—nothing is sent to a server, stored, or logged.
Features
Besides your own images, you can check an entire color palette using hex or RGB values—useful for web design, brand colors and charts.
Five types of color blindness side by side
Alongside the original, the simulator shows each color with protanopia, deuteranopia, tritanopia, achromatopsia and deuteranomaly at the same time. You can see at a glance where two colors blend together.
Check an entire color palette at once
Use the plus button to add as many colors as you like, such as your entire brand palette. Each color’s hex value appears below it, and every simulated variant shows the entire palette.
Color field, hex or RGB
Choose colors in the color field with the hue slider, enter a hex or RGB value, or generate a new color with “Random Color”.
Simulate your own images
Optionally upload a PNG or JPG up to 15 MB, such as a screenshot, logo or chart. Large images are scaled down to 1,600 px on the longest side for the preview, and you can click to enlarge each preview.
Scientific simulation model
The simulation is based on the model by Machado, Oliveira & Fernandes (2009) and runs in the linear RGB color space. Color swatches and image pixels undergo the same processing.
Everything stays in your browser
Colors and images are processed directly in your browser. Nothing is sent to a server, stored or logged, and you don’t need an account.
Types of color blindness
Most people with color blindness can see colors but confuse certain shades. Which shades depends on the type of color vision deficiency.
| Type | How colors appear | Simulation in the tool |
|---|---|---|
| Protanopia (red blindness) | Red and green are hard to distinguish. Reds appear darker and shift toward olive, brown and yellow. | Full severity (level 1.0) |
| Deuteranopia (green blindness) | Red and green are confused and appear as similar shades of yellow, brown and olive. | Full severity (level 1.0) |
| Tritanopia (blue blindness) | Blue and green, as well as yellow and violet, are hard to distinguish. Yellow appears pale pink to light gray. Red and green remain easy to distinguish. | Full severity (level 1.0) |
| Achromatopsia (complete color blindness) | Almost no colors are perceived, only differences in brightness, much like a grayscale image. | Relative luminance (grayscale) |
| Deuteranomaly (reduced green sensitivity) | A milder form of deuteranopia and the most common color vision deficiency: red and green shades appear more similar. | Mild form (severity 0.6) |
Try it yourself: Enter #FF0000 in the simulator, use the plus button to add a second color and set it to #00FF00. In the Protanopia and Deuteranopia cards, you’ll immediately see that both colors become shades of yellow and olive, differing almost only in brightness.
How it works
From your first color to a comparison of all five variants, using your palette and optionally your own image.
Step 1
In the “Edit Color” section, choose a color in the color field with the hue slider, enter a hex or RGB value, or click “Random Color”.
Step 2
Use the plus button under “Your Color Palette” to add more colors. Click a color to load it into the picker for editing, or use the trash icon to remove it.
Step 3
Drag a PNG or JPG up to 15 MB into the “Upload your own image” field, or click it to select a file. The image stays in your browser.
Step 4
Under “Simulated Preview,” compare the original with protanopia, deuteranopia, tritanopia, achromatopsia and deuteranomaly. Look for colors that become too similar.
Step 5
Click a preview image to enlarge it and inspect the details.
Step 6
Use the links below the preview to open the selected color in the Color Picker or Color Scheme Generator, or check its contrast in the Contrast Checker.
Accessible colors
Red-green color vision deficiencies affect about 8 % of men and around 0.5 % of women (particularly those of European ancestry), an estimated 300 million people worldwide. If you convey important information solely through color, such as red for “error” and green for “success” without an additional symbol or text, you unintentionally exclude a significant share of your users.
The WCAG therefore require that color never be the only way to distinguish information (success criterion 1.4.1). Combine colors with icons, patterns or labels, and use the simulator to check which colors in your palette become too similar with a color vision deficiency. Then use the Contrast Checker to check whether text and background have enough contrast. Go to Contrast Checker
Discover more
Check contrast, adjust colors, generate a color scheme or extract colors from an image, also free in your browser.
Calculate the WCAG contrast ratio between two colors live and check it against AA/AAA standards and UI components—all in your browser.
Built by Justin Schuessler
Convert colors between HEX, RGB, HSL, HSV, and CMYK in real time, find the closest CSS named color, and check WCAG contrast against black and white—all in your browser.
Built by Justin Schuessler
Generate complementary, analogous, triadic, and other color schemes live from a base color—nothing is stored or transmitted.
Built by Justin Schuessler
Extract a color code from an image: eyedropper with magnifier, HEX, RGB, and HSL values, the image's color palette, and a contrast tip. The image stays in your browser.
Built by Dimitri Heissler
FAQ
Quick answers about color vision deficiencies, accessible colors and this tool.
Most people with color blindness can see colors but confuse certain shades. With protanopia and deuteranopia, red and green become similar shades of yellow, brown and olive. With tritanopia, blue and green, as well as yellow and violet, are hard to distinguish. Only achromatopsia removes color entirely, leaving differences in brightness like those in a grayscale image. You can see this directly with your own colors in the simulator.
Five types alongside the original: protanopia (red blindness), deuteranopia (green blindness), deuteranomaly (reduced green sensitivity), tritanopia (blue blindness) and achromatopsia (complete color blindness). All five are displayed side by side at the same time for every color in your palette and for an uploaded image.
Red-green deficiencies are the most common, especially deuteranomaly, a milder form of reduced green sensitivity. Red-green deficiencies affect about 8 % of men and around 0.5 % of women (figures for people of European ancestry), or an estimated 300 million people worldwide. Women can also have color blindness, though it is much less common.
No. The simulator shows how people with a color vision deficiency perceive colors. It is neither a vision test nor a diagnosis. If you want to have your own color vision tested, consult an eye doctor or optician, who may use Ishihara plates, for example.
The Color Blindness Simulator is free to use without signing up. Images are not uploaded: The tool reads the file directly in your browser and generates the variants using Canvas, with no transfer to a server, storage or logging. PNG and JPG files up to 15 MB are supported. For the preview, images are scaled down to a maximum of 1,600 px on the longest side. Close the tab and the image is gone.
Yes. Use the plus button to add as many colors as you like and see them all at once in each of the five simulated variants. Click a color to load it into the picker for editing, or use the trash icon to remove it. This lets you see whether two colors in your palette, such as your brand colors, become too similar with a color vision deficiency.
The simulation uses the physiologically based model by Machado, Oliveira & Fernandes (2009) and its published matrices, calculated in the linear RGB color space after conversion from sRGB. Protanopia, deuteranopia and tritanopia are simulated at full severity (level 1.0), deuteranomaly at severity level 0.6, and achromatopsia as relative luminance. The severity of a color vision deficiency varies from person to person, so the simulation shows a typical perception.
Red and green are particularly problematic, but so are green and brown or blue and violet when color is the only way to distinguish them. Instead of removing colors altogether, add text, icons or patterns and check your palette in the simulator. If two colors look almost identical in one variant, adjust their brightness or hue. Then use the Contrast Checker to check the contrast between text and background.
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