class Blend {
 static int normal(int a, int b) => b;

 static int overlay(num a, num b) {
   a /= 255;
   b /= 255;
   var result = 0;

   if (a < 0.5) result = 2 * a * b;
   else result = 1 - 2 * (1 - a) * (1 - b);

   return min(255, max(0, result * 255)).toInt();
 }

 static int hardLight(int a, int b) => Blend.overlay(b, a);

 static int softLight(num a, num b) {
   a /= 255;
   b /= 255;

   var v = ((1 - 2 * b) * a + 2 * b) * a;
   return limitValue((v * 255).toInt(), 0, 255);
 }

 static int dodge(int a, int b) => min(256 * a ~/ (255 - b + 1), 255);
 static int burn(int a, int b) => 255 - min(256 * (255 - a) ~/ (b + 1), 255);
 static int multiply(int a, int b) => b * a ~/ 255;
 static int divide(int a, int b) => min(256 * a ~/ (b + 1), 255);
 static int screen(int a, int b) => 255 - (255 - b) * (255 - a) ~/ 255;
 static int grainExtract(int a, int b) => limitValue(a - b + 128, 0, 255);
 static int grainMerge(int a, int b) => limitValue(a + b - 128, 0, 255);
 static int difference(int a, int b) => (a - b).abs();
 static int addition(int a, int b) => min(a + b, 255);
 static int substract(int a, int b) => max(a - b, 0);
 static int darkenOnly(int a, int b) => min(a, b);
 static int lightenOnly(int a, int b) => max(a, b);

 static List<int> color(List<int> a, List<int> b) {
   var aHSL = rgbListToHsl(a);
   var bHSL = rgbListToHsl(b);

   return hslToRgb(bHSL[0], bHSL[1], aHSL[2]);
 }

 static List<int> hue(List<int> a, List<int> b) {
   var aHSV = rgbListToHsv(a);
   var bHSV = rgbListToHsv(b);

   if(bHSV[1] == 0) return hsvToRgb(aHSV[0], aHSV[1], aHSV[2]);
   else return hsvToRgb(bHSV[0], aHSV[1], aHSV[2]);
 }

 static List<int> value(List<int> a, List<int> b) {
   var aHSV = rgbListToHsv(a);
   var bHSV = rgbListToHsv(b);

   return hsvToRgb(aHSV[0], aHSV[1], bHSV[2]);
 }

 static List<int> saturation(List<int> a, List<int> b) {
   var aHSV = rgbListToHsv(a);
   var bHSV = rgbListToHsv(b);

   return hsvToRgb(aHSV[0], bHSV[1], aHSV[2]);
 }
}