contrastY function

double contrastY(
  1. double y1,
  2. double y2
)

Contrast ratio of two luminances, (Y_lighter + 0.05) / (Y_darker + 0.05), in 1, 21.

Implementation

double contrastY(double y1, double y2) =>
    y1 > y2 ? (y1 + 0.05) / (y2 + 0.05) : (y2 + 0.05) / (y1 + 0.05);