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);
}