Color Contrast Simulator by Condition
Explore a local visual approximation with WCAG numerical reference thresholds; this is not a diagnosis or accessibility certification.
A QUICK WALKTHROUGH
How to use this tool
- Choose opaque foreground and background sRGB colors.
- Select deuteranopia, protanopia or tritanopia.
- Compare the original and simulated previews, relative luminance and contrast; copy the summary.
Simulation model
Uses linear-sRGB Viénot 1999 matrices for protanopia and deuteranopia, and Brettel 1997 two-plane projection for tritanopia, using public-domain libDaltonLens coefficients. The reference site names the conditions but does not disclose coefficients; this tool does not claim identical output. Full dichromacy only, with gamut clipping and 8-bit sRGB rounding.
Contrast scope
Relative luminance uses 0.2126R + 0.7152G + 0.0722B after sRGB linearization. Reference AA thresholds are 4.5:1 for normal text and 3:1 for large text (18pt, or 14pt bold). Threshold comparisons use unrounded ratios. WCAG evaluation uses original colors; simulated-color ratios are illustrative checks, not a separate compliance test.
GOOD TO KNOW
Common questions
Does this diagnose color vision?
No. Individual color vision, displays and viewing conditions vary. These models are visual approximations and do not represent every person or replace clinical assessment.
Does a threshold match prove accessibility?
No. This checks one opaque color pair only. It does not evaluate font rendering, transparency, focus, non-text content, screen readers or a complete page.