avoidRedBlackWhitePaletteFilter function

bool avoidRedBlackWhitePaletteFilter(HSLColor color)

A basic PaletteFilter, which rejects colors near black, white and low saturation red.

Use this as an element in the filters list given to PaletteGenerator.fromImage.

See also:

• PaletteGenerator, a class for selecting color palettes from images.

Implementation

bool avoidRedBlackWhitePaletteFilter(HSLColor color) {
  bool isBlack(HSLColor hslColor) {
    const double blackMaxLightness = 0.05;
    return hslColor.lightness <= blackMaxLightness;
  }

  bool isWhite(HSLColor hslColor) {
    const double whiteMinLightness = 0.95;
    return hslColor.lightness >= whiteMinLightness;
  }

  // Returns true if the color is close to the red side of the I line.
  bool isNearRedILine(HSLColor hslColor) {
    const double redLineMinHue = 10.0;
    const double redLineMaxHue = 37.0;
    const double redLineMaxSaturation = 0.82;
    return hslColor.hue >= redLineMinHue &&
        hslColor.hue <= redLineMaxHue &&
        hslColor.saturation <= redLineMaxSaturation;
  }

  return !isWhite(color) && !isBlack(color) && !isNearRedILine(color);
}