Types of Color Blindness
Color blindness (color vision deficiency) affects how people perceive colors. About 8% of males and 0.5% of females have some form of color vision deficiency. Understanding these conditions helps designers create more inclusive products.
Protanopia
Absence of red-sensitive cones. Red appears dark; cannot distinguish red from green or blue from purple.
Deuteranopia
Absence of green-sensitive cones. Most common form. Green appears similar to red or orange.
Tritanopia
Absence of blue-sensitive cones. Blue appears green; yellow and red may appear pink.
Achromatopsia
Complete color blindness — only shades of gray are perceived. Very rare (1 in 30,000).
Frequently Asked Questions
Color blindness (color vision deficiency) is the reduced ability to distinguish certain colors. It's caused by the absence or malfunction of specific cone types in the retina. Approximately 300 million people worldwide have some form of color blindness, making accessibility design crucial for inclusive products.
The simulator applies color transformation matrices in LMS color space (which approximates how the human eye's cone cells respond to light). Each pixel's RGB values are converted through the specific matrix for the selected deficiency type and converted back to RGB. This is the standard method used by accessibility tools like Sim Daltonism.
Designs that rely on color alone to convey information exclude users with color vision deficiencies. WCAG 2.1 guideline 1.4.1 (Color: Level A) requires that color is not the only visual means of distinguishing elements. Testing with a simulator helps catch issues before launch.
Protanopia is the complete absence of red cone function. Protanomaly is reduced (not absent) red cone sensitivity — colors appear shifted but can still be partially distinguished. The "-anomaly" variants (protanomaly, deuteranomaly, tritanomaly) are less severe than the "-opia" variants but still impact color perception.
Key strategies: (1) Use icons, patterns, or labels alongside color coding; (2) Ensure adequate contrast ratios (WCAG AA: 4.5:1 for text); (3) Use color-blind-safe palettes from ColorBrewer or similar tools; (4) Test with a simulator like this one; (5) Never rely on red-green contrast alone as the sole indicator.