Free Online Color Blindness Simulator
Upload any image and instantly see how it appears to people with different types of color vision deficiency. 100% free, private, and works in your browser.
Drop your image here or click to upload
Choose an image to simulate color blindness
Original Image
—Upload an image to begin
Simulated — Protanopia
ProtanopiaClick "Simulate" to see results
What Is a Color Blindness Simulator and How Does It Work?
A color blindness simulator is a specialized digital tool that transforms images to accurately represent how they appear to individuals affected by various types of color vision deficiency (CVD). Also known as color vision deficiency simulator or daltonism simulator, this tool applies mathematically derived color transformation matrices to every pixel in an image, recalculating RGB values to simulate the reduced or altered color perception experienced by approximately 8% of men and 0.5% of women worldwide.
Color blindness is not actual blindness — it is a reduced ability to distinguish between certain colors. Most people with CVD can see colors clearly but may confuse shades of red and green, or blue and yellow. In rare cases, individuals see the world entirely in shades of gray. The ToolGalaxy Color Blindness Simulator covers all major categories: Protanopia (red cone absence), Deuteranopia (green cone absence), Tritanopia (blue cone absence), Achromatopsia (complete lack of color vision), and their partial variants (Protanomaly, Deuteranomaly, Tritanomaly, Achromatomaly).
Why Is Color Blindness Simulation Important for Designers?
For web designers, UI/UX professionals, graphic artists, and product developers, understanding how color choices affect users with CVD is essential. Approximately 1 in 12 men has some form of red-green color blindness, making it one of the most common accessibility considerations. Using a color blindness simulator during the design process helps identify potential issues such as:
- Text that becomes unreadable against its background when colors shift
- Data visualizations, charts, and graphs that lose meaning without color distinction
- Interactive elements like buttons, links, and form fields that become indistinguishable
- Status indicators (error/warning/success) that rely solely on color coding
- Navigation menus and maps that become confusing without clear color differentiation
By testing designs with this simulator, creators can proactively add patterns, labels, icons, and text annotations to ensure information remains accessible to all users. This practice aligns with WCAG 2.1 accessibility guidelines, specifically the requirement that color should not be used as the sole visual means of conveying information.
How Does This Tool Process Images?
This simulator uses the HTML5 Canvas API to process images entirely within your browser. When you upload an image, it is drawn onto a hidden canvas element, and the pixel data (RGBA values for each pixel) is extracted. The tool then applies a 3×3 color transformation matrix specific to the selected type of color blindness. These matrices are based on established scientific research, including the work of Brettel, Viénot, and Mollon (1997) for dichromatic simulations and Machado, Oliveira, and Fernandes (2009) for anomalous trichromacy simulations.
The severity slider allows you to adjust the intensity of the simulation from 0% (no change) to 100% (full simulation). This is achieved by linearly interpolating between the original RGB values and the fully simulated values for each pixel. All computation happens locally — your images never leave your device, ensuring complete privacy and instant results without server uploads or network latency.
Types of Color Vision Deficiency Explained
Protanopia
Complete absence of red cone cells. Reds appear dark and muted; reds and greens become hard to distinguish. Affects ~1.2% of males.
Protanomaly
Reduced sensitivity to red light. Colors appear shifted but some red-green distinction remains. Affects ~1.3% of males.
Deuteranopia
Complete absence of green cone cells. The most common severe form — reds and greens appear yellowish-brown. Affects ~1.2% of males.
Deuteranomaly
Reduced sensitivity to green light. The single most common form of CVD, affecting ~5% of males. Greens shift toward reds.
Tritanopia
Complete absence of blue cone cells. Blues appear green; yellows appear pink or light. Very rare, affecting ~0.001% equally in both sexes.
Achromatopsia
Complete color blindness — the world is seen only in shades of gray. Extremely rare (~1 in 33,000). Also causes light sensitivity.