Color Blindness Simulator

Types of Color Blindness

Color blindness — more accurately called color vision deficiency — affects approximately 8% of males and 0.5% of females of Northern European descent. The condition results from missing or malfunctioning photoreceptor cells (cones) in the retina.

Red-Green Color Blindness (Most Common)

These are by far the most common forms, affecting roughly 1 in 12 males:

• Deuteranopia — Missing M-cones (medium-wavelength/green-sensitive). Affects ~5–6% of males. Red and green appear similar; both may look yellow or brown.
• Deuteranomaly — M-cones present but shifted. The most common single form of color blindness (~5% of males). Greens appear more red.
• Protanopia — Missing L-cones (long-wavelength/red-sensitive). Affects ~1% of males. Reds appear dark/black; red-green discrimination is lost.
• Protanomaly — L-cones present but shifted. Reds appear less bright and distinct (~1% of males).

Blue-Yellow Color Blindness

• Tritanopia — Missing S-cones (short-wavelength/blue-sensitive). Very rare, affecting roughly 1 in 10,000 people of all genders. Blues appear green; yellows appear violet or light grey.
• Tritanomaly — S-cones present but shifted. Extremely rare. Blue appears greener.

Total Color Blindness

• Achromatopsia — Complete absence of color vision; only brightness is perceived. Affects roughly 1 in 30,000 people. Often accompanied by photophobia (light sensitivity) and reduced visual acuity.

Color blindness is usually inherited (X-linked recessive for red-green types), which explains the higher prevalence in males. Acquired color blindness can also result from certain diseases, medications, or aging.

Design Tips for Color Accessibility

When designing for color-blind audiences, consider these evidence-based strategies:

Use More Than Color Alone

Never rely solely on color to convey information. Supplement with:

• Shape or icon (e.g., checkmarks vs. X marks, not just red vs. green)
• Pattern or texture in charts and maps
• Text labels directly on data points
• Position or size differences

Choose Color-Blind-Friendly Palettes

• Blue and orange are distinguishable across almost all types of color blindness — a reliable pair for data visualization.
• Avoid red–green combinations for critical signals.
• The Wong palette and Okabe–Ito palette are widely recommended for scientific figures.
• Use sufficient lightness contrast in addition to hue contrast.

Test Your Designs

Use tools like this simulator to review designs before publishing. Export your key screens, upload them here, and check each simulation. Pay special attention to charts, status indicators, and call-to-action buttons.

WCAG Color Contrast

While WCAG contrast requirements primarily target low vision rather than color blindness, meeting AA contrast ratios (4.5:1 for normal text) naturally improves readability for people with color vision deficiencies because it ensures sufficient luminance difference regardless of hue.

Simulating Color Blindness in GIMP

GIMP has a built-in color deficiency display filter that lets you preview your artwork as you work:

1. Open your image in GIMP.
2. Go to View → Display Filters…
3. Double-click Color Deficiency to add it to the active filters list.
4. Select the deficiency type: Protanopia, Deuteranopia, or Tritanopia.
5. Adjust the Severity slider (0 = no effect, 1 = full simulation).
6. Click OK — GIMP will render the canvas in the simulated mode without altering the actual file.

To switch back to normal view, simply return to View → Display Filters… and remove the filter.

For a permanent flattened simulation (useful for client presentations), use Filters → Colors → Hue-Saturation in combination with Colors → Curves to manually approximate the color shifts, then export to a separate file.