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Color Blindness Simulator

Verify WCAG color contrast compliance by simulating how your UI mockups and images appear to users with different forms of color blindness.

Designing for Everyone: The Importance of Color Blindness Simulators

Approximately 1 in 12 men (8%) and 1 in 200 women (0.5%) suffer from some form of color vision deficiency (CVD). In web design, relying solely on color to communicate state—such as making an input border red for "Error" and green for "Success"—completely alienates millions of users. The RapidCalc Color Blindness Simulator allows developers and UX designers to verify that their interfaces remain legible and structurally clear regardless of the user's visual capabilities.

The Three Primary Types of Color Blindness

  • Protanopia (Red-Blind): A severe form of red-green color blindness caused by a lack of red retinal photoreceptors. Reds appear darker and often shift toward brown or black, while greens, yellows, and oranges all blend into similar yellowish hues.
  • Deuteranopia (Green-Blind): The most common form of color blindness. Users lack green photoreceptors. While similar to Protanopia, reds do not appear as dark. However, the contrast between red and green UI elements is almost entirely lost.
  • Tritanopia (Blue-Blind): A much rarer condition affecting the short-wavelength cones. Users struggle to distinguish between blue and green, as well as yellow and red. The world appears largely in shades of cyan and pink.

How Does This Browser Simulator Work?

Instead of merely applying a generic CSS desaturation overlay, RapidCalc utilizes precise mathematical SVG Color Matrices. When you select a deficiency from the dropdown, the HTML5 Canvas recalculates the exact RGB values of every pixel in your image using an industry-standard matrix transformation. For instance, the matrix for Deuteranopia forcefully bleeds the Red and Green channels together while preserving the Blue channel.

100% Client-Side Privacy

Because designers frequently work with unreleased proprietary UI mockups, uploading images to external servers poses a massive corporate security risk. This RapidCalc utility processes the image entirely within your own computer's memory using the native HTML5 Canvas API, ensuring absolute privacy.