relativeLuminance static method

double relativeLuminance(
  1. Color color
)

The relative luminance of color, in the range [0, 1].

color's alpha is ignored — composite it over its background first with compositeOver if it isn't already opaque.

Implementation

static double relativeLuminance(Color color) {
  double linearize(double channel) {
    return channel <= 0.03928
        ? channel / 12.92
        : math.pow((channel + 0.055) / 1.055, 2.4).toDouble();
  }

  final r = linearize(color.r);
  final g = linearize(color.g);
  final b = linearize(color.b);
  return 0.2126 * r + 0.7152 * g + 0.0722 * b;
}