What is Color Blindness Simulator?

Color Blindness Simulator helps you see how your images and colors appear to people with color vision deficiency (CVD). About 8% of men and 0.5% of women have some form of color blindness, making it essential for designers to test their work for accessibility.

Accessibility matters: Approximately 1 in 12 men and 1 in 200 women worldwide experience some form of color vision deficiency. Testing your designs ensures everyone can access your content effectively.

Why Use This Tool?

When designing websites, apps, or graphics, colors that look distinct to you may appear identical to someone with color blindness. This tool lets you:

Test Designs Early

Catch accessibility issues before publishing and avoid costly redesigns.

Compare CVD Types

See how different color vision deficiencies affect perception simultaneously.

Check Color Palettes

Test individual colors to ensure your palette is accessible to everyone.

Types of Color Blindness Supported

Deuteranopia Most Common

Green-blind vision affecting approximately 6% of men. This is the most prevalent form of color vision deficiency.

Protanopia

Red-blind vision affecting approximately 1% of men. Difficulty distinguishing red from green and dark colors.

Tritanopia Rare

Blue-blind vision affecting less than 0.1% of people. Difficulty distinguishing blue from yellow.

Achromatopsia Very Rare

Total color blindness where the world appears in grayscale. Extremely rare condition.

Your Data Stays Private

All processing happens in your browser with complete privacy protection:

No uploads - Images never leave your device
No tracking - We don't collect or store your images
Instant results - No server processing delays
Works offline - Once loaded, no internet connection required

100% Client-Side Processing: Your images are processed entirely in your browser using JavaScript and Canvas API. Zero data transmission means complete privacy and security.

How to Use Color Blindness Simulator

Testing Images for Accessibility

Test how your images appear to people with color vision deficiency:

Upload an Image

Click the upload zone, drag and drop, or paste from clipboard (Ctrl+V). You can also use the webcam to capture photos directly.

Select CVD Type

Choose from Deuteranopia, Protanopia, Tritanopia, or Achromatopsia to simulate specific color vision deficiencies.

Compare Results

Drag the slider to compare original vs. simulated view side by side. This helps identify problematic color combinations.

View All Types

Click "All" to see how your image looks across all CVD types simultaneously in a grid layout.

Download Results

Save the simulated image for documentation, sharing with team members, or accessibility reports.

Testing Individual Colors

Test individual colors for accessibility across all CVD types:

Switch to Color Tab

Click the "Color" button at the top of the interface to access color testing mode.

Enter a Color

Use the color picker for visual selection or type a HEX code directly (e.g., #FF5733).

View Results

See how your color appears across all CVD types instantly. Compare how different deficiencies affect the same color.

Quick Tips for Best Results

Try Sample Images

Use the built-in colorful samples to understand how different colors are affected by various CVD types.

Test with Webcam

Capture photos directly to test real-world scenarios like printed materials or physical products.

Focus on Deuteranopia

It's the most common type, affecting ~6% of men. Start here for maximum accessibility impact.

Pro Tip: When testing designs, pay special attention to critical UI elements like buttons, links, and status indicators. These should remain distinguishable across all CVD types.

Features

Multiple Input Methods

Flexible options to load images for testing:

File Upload

Click to browse or drag and drop images directly into the interface.

Supports JPEG, PNG, GIF, WebP
Preserves transparency in PNG

Clipboard Paste

Press Ctrl+V to paste screenshots or copied images instantly.

Quick screenshot testing
No file saving required

Webcam Capture

Take photos directly from your camera for real-world testing.

Test physical materials
Capture printed designs

Sample Images

Built-in colorful samples for quick testing and learning.

Instant demonstration
No upload needed

Four CVD Types

Comprehensive simulation covering all major color vision deficiencies:

Deuteranopia (Green-blind) ~6%

Protanopia (Red-blind) ~1%

Tritanopia (Blue-blind) <0.1%

Achromatopsia (Total color blindness) Very Rare

Comparison Tools

Powerful visualization options to analyze accessibility:

Slider comparison - Drag to reveal original vs. simulated side by side for precise comparison
All types grid - View all CVD simulations at once for quick comparison across deficiency types
Color mode - Test individual HEX colors across all CVD types to validate your color palette

Export Options

Save and share your accessibility testing results:

Download simulated images - Save as PNG with CVD type automatically included in filename
Instant processing - No waiting for server responses, immediate results
High quality output - Maintains original image quality and resolution

Privacy First

Your data security is our priority:

Traditional Tools

Server-Based Processing

Images uploaded to servers
Potential data collection
Requires internet connection
Processing delays

Our Simulator

Client-Side Processing

100% browser-based processing
Zero data collection
Works offline after loading
Instant results

Client-side image processing ensures complete privacy. Your images never leave your device, making this tool safe for testing confidential designs and unreleased products.
— Web Accessibility Best Practices

Frequently Asked Questions

What is color blindness?

Color blindness, or color vision deficiency (CVD), is a condition where people have difficulty distinguishing certain colors. The most common types affect red-green perception, while rarer forms affect blue-yellow or result in complete color blindness.

Key facts:

Affects approximately 8% of men and 0.5% of women globally
Usually inherited genetically through the X chromosome
Red-green deficiency is most common (Deuteranopia and Protanopia)
Can also be acquired through aging, medications, or eye diseases

How accurate is this simulator?

This simulator uses the Brettel-Viénot algorithm, a scientifically validated method for simulating color vision deficiency. While no simulation can perfectly replicate how someone with CVD sees, it provides a reliable approximation for accessibility testing.

Scientific basis: The Brettel-Viénot algorithm is based on physiological models of human color vision and has been validated through research with individuals who have color vision deficiencies.

Which CVD type should I test for?

Start with Deuteranopia (green-blind) as it's the most common type, affecting approximately 6% of men. If your design passes this test, also check Protanopia and Tritanopia for comprehensive coverage.

Recommended testing priority:

Priority 1 Deuteranopia - Most common, affects ~6% of men
Priority 2 Protanopia - Second most common, affects ~1% of men
Priority 3 Tritanopia - Rare but important for comprehensive testing
Optional Achromatopsia - Very rare, test if serving critical applications

Are my images uploaded to a server?

No. All image processing happens entirely in your browser using JavaScript and the Canvas API. Your images never leave your device, ensuring complete privacy.

Privacy guarantee: This tool operates 100% client-side. No data transmission occurs, making it safe for testing confidential designs, unreleased products, or sensitive materials.

What image formats are supported?

The simulator supports all common image formats including:

JPEG/JPG - Standard photo format
PNG - Supports transparency (alpha channel preserved)
GIF - Animated and static images
WebP - Modern web format

PNG images with transparency are fully supported - the alpha channel is preserved during simulation.

Why do some colors look the same after simulation?

This is exactly what the simulator is designed to show. When two colors appear identical in the simulated view, it means people with that type of color blindness cannot distinguish between them.

Design recommendation: When colors become indistinguishable, consider using different colors or adding other visual cues like patterns, textures, labels, or icons to convey information.

Common problematic combinations:

Red and green (Deuteranopia/Protanopia)
Blue and purple (Deuteranopia)
Blue and green (Tritanopia)
Pink and gray (Protanopia)

Can I use this for WCAG compliance testing?

This tool helps identify potential color accessibility issues, but WCAG compliance also requires meeting specific contrast ratios. Use this simulator alongside a contrast checker for comprehensive accessibility testing.

WCAG requirements include:

Contrast ratios - Minimum 4.5:1 for normal text, 3:1 for large text (Level AA)
Color independence - Information shouldn't rely on color alone
Focus indicators - Visible keyboard focus with sufficient contrast

Best practice: Combine this CVD simulator with contrast ratio checkers and manual testing to ensure full WCAG 2.1 Level AA or AAA compliance.

What's the maximum image size?

Images larger than 2000 pixels are automatically resized to ensure smooth performance. The aspect ratio is preserved during resizing.

Technical details:

Maximum dimension: 2000px (width or height)
Aspect ratio: Always preserved
Quality: High-quality resizing algorithm
Performance: Optimized for instant processing

This limitation ensures the simulator remains fast and responsive while maintaining sufficient detail for accessibility testing.