Image Tools
Color Blindness Simulator
Upload an image or pick colors and see how they appear under different types of color blindness. OpenToolLab's simulator runs entirely in your browser — your images never leave your device.
Simulated views
What makes this tool different
7 color blindness types
Simulate protanopia, deuteranopia, tritanopia, achromatopsia, protanomaly, deuteranomaly, and tritanomaly.
Image upload support
Upload any image to see how it appears under different color blindness conditions.
Before/after comparison
Side-by-side or slider comparison shows the original and simulated versions simultaneously.
100% client-side
All simulation happens in your browser using Canvas API. Your images are never uploaded to any server.
About this tool
Color Blindness Simulator: everything you need to know
Approximately 8% of men and 0.5% of women have some form of color vision deficiency. That means roughly 1 in 12 men and 1 in 200 women cannot distinguish between certain colors — most commonly red and green. If your website, app, or design relies on color alone to convey information, you are excluding a significant portion of your audience.
OpenToolLab's free color blindness simulator lets you see your designs through the eyes of color-blind users. Upload an image or enter color values, select from 7 types of color vision deficiency, and see an accurate simulation of how your content appears. The before/after comparison makes it easy to identify accessibility issues.
The simulator uses scientifically validated color transformation matrices from Machado et al. (2009), the most comprehensive research on color blindness simulation. It covers protanopia (no red cones), deuteranopia (no green cones), tritanopia (no blue cones), achromatopsia (complete color blindness), and three milder anomalous types.
Privacy is guaranteed because all processing happens in your browser using the Canvas API. Your images are loaded into browser memory, processed locally, and never sent to any server. This is critical for designers working with unreleased products, confidential branding, or proprietary visual assets.
Common use cases include testing website accessibility for WCAG compliance, reviewing UI designs before launch, checking color palettes for contrast issues, validating data visualizations for color-blind audiences, and ensuring marketing materials are accessible. The tool is essential for designers, developers, and product managers who care about inclusive design.
OpenToolLab imposes no limits on usage. Test as many images and color palettes as you need, with no signup and no premium tier. The tool works offline after the first load, making it usable in secure design environments.
FAQ
Color Blindness Simulator — frequently asked questions
What is a color blindness simulator?
A color blindness simulator shows how images, designs, and color palettes appear to people with different types of color vision deficiency. It applies color transformation matrices to simulate protanopia, deuteranopia, tritanopia, and other forms.
How do I simulate color blindness?
Upload an image or enter color values, select a color blindness type from the dropdown, and see the simulated result instantly. The tool shows you exactly what a color-blind person would see.
What types of color blindness can be simulated?
The simulator covers 7 types: protanopia (no red cones), deuteranopia (no green cones), tritanopia (no blue cones), achromatopsia (no color), and three milder anomalous types (protanomaly, deuteranomaly, tritanomaly).
Can I upload my own image?
Yes. Drag and drop any image or click to browse. The image is processed entirely in your browser — it is never uploaded to any server.
Is this tool free and private?
Yes. All simulation happens in your browser using Canvas API. Your images never leave your device — there is no upload, no server processing, and no data collection.
How do I check if my design is color-blind safe?
Upload your design or screenshot, simulate each type of color blindness, and look for elements that become indistinguishable. If colors merge or contrast drops, adjust your palette.
What is deuteranopia?
Deuteranopia is the most common form of color blindness, affecting about 1% of males. People with deuteranopia cannot perceive green light, making red and green appear as similar shades of yellow or brown.
Can I simulate color blindness on a color palette?
Yes. Enter your hex or RGB color values and see how each color transforms under different color blindness types. This helps you choose accessible palettes.
How accurate is the simulation?
The simulation uses scientifically validated color transformation matrices based on research from Machado et al. (2009). It provides an accurate approximation of how color-blind individuals perceive colors.
Can I use this for accessibility testing?
Yes. The simulator is a valuable tool for WCAG accessibility testing. It helps identify color contrast issues and ensures your designs are usable by people with color vision deficiency.
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