image/lib/src/color.dart - third_party/dart-pkg - Git at Google

 import 'dart:math';

 import 'image_exception.dart';
 import 'internal/clamp.dart';

 /// Image pixel colors are instantiated as an int object rather than an instance
 /// of the Color class in order to reduce object allocations. Image pixels are
 /// stored in 32-bit RGBA format (8 bits per channel). Internally in dart, this
 /// will be stored in a "small integer" on 64-bit machines, or a
 /// "medium integer" on 32-bit machines. In Javascript, this will be stored
 /// in a 64-bit double.
 ///
 /// The Color class is used as a namespace for color operations, in an attempt
 /// to create a cleaner API for color operations.
 class Color {
   /// Create a color value from RGB values in the range [0, 255].
   static int fromRgb(int red, int green, int blue) {
     return getColor(red, green, blue);
   }

   /// Create a color value from RGBA values in the range [0, 255].
   static int fromRgba(int red, int green, int blue, int alpha) {
     return getColor(red, green, blue, alpha);
   }

   /// Create a color value from HSL values in the range [0, 1].
   static int fromHsl(num hue, num saturation, num lightness) {
     var rgb = hslToRGB(hue, saturation, lightness);
     return getColor(rgb[0], rgb[1], rgb[2]);
   }

   /// Create a color value from HSV values in the range [0, 1].
   static int fromHsv(num hue, num saturation, num value) {
     var rgb = hsvToRGB(hue, saturation, value);
     return getColor(rgb[0], rgb[1], rgb[2]);
   }

   /// Create a color value from XYZ values.
   static int fromXyz(num x, num y, num z) {
     var rgb = xyzToRGB(x, y, z);
     return getColor(rgb[0], rgb[1], rgb[2]);
   }

   /// Create a color value from CIE-L*ab values.
   static int fromLab(num L, num a, num b) {
     var rgb = labToRGB(L, a, b);
     return getColor(rgb[0], rgb[1], rgb[2]);
   }

   /// Compare colors from a 3 or 4 dimensional color space
   static num distance(List<num> c1, List<num> c2, bool compareAlpha) {
     num d1 = c1[0] - c2[0];
     num d2 = c1[1] - c2[1];
     num d3 = c1[2] - c2[2];
     if (compareAlpha) {
       num dA = c1[3] - c2[3];
       return sqrt(max(d1 * d1, (d1 - dA) * (d1 - dA)) +
           max(d2 * d2, (d2 - dA) * (d2 - dA)) +
           max(d3 * d3, (d3 - dA) * (d3 - dA)));
     } else {
       return sqrt(d1 * d1 + d2 * d2 + d3 * d3);
     }
   }
 }

 /// Blue channel of a color.
 const int BLUE = 0;

 /// Green channel of a color.
 const int GREEN = 1;

 /// Red channel of a color.
 const int RED = 2;

 /// Alpha channel of a color.
 const int ALPHA = 3;

 /// Luminance of a color.
 const int LUMINANCE = 4;

 /// Get the color with the given [r], [g], [b], and [a] components.
 ///
 /// The channel order of a uint32 encoded color is RGBA, to be consistent
 /// with the image data of a canvas html element.
 int getColor(int r, int g, int b, [int a = 255]) =>
     (clamp255(a) << 24) |
     (clamp255(r) << 16) |
     (clamp255(g) << 8) |
     (clamp255(b));

 /// Get the [channel] from the [color].
 int getChannel(int color, int channel) => channel == RED
     ? getRed(color)
     : channel == GREEN
         ? getGreen(color)
         : channel == BLUE ? getBlue(color) : getAlpha(color);

 /// Returns a new color, where the given [color]'s [channel] has been
 /// replaced with the given [value].
 int setChannel(int color, int channel, int value) => channel == RED
     ? setRed(color, value)
     : channel == GREEN
         ? setGreen(color, value)
         : channel == BLUE ? setBlue(color, value) : setAlpha(color, value);

 /// Get the blue channel from the [color].
 int getBlue(int color) => (color) & 0xff;

 /// Returns a new color where the blue channel of [color] has been replaced
 /// by [value].
 int setBlue(int color, int value) => (color & 0xffffff00) | (clamp255(value));

 /// Get the green channel from the [color].
 int getGreen(int color) => (color >> 8) & 0xff;

 /// Returns a new color where the green channel of [color] has been replaced
 /// by [value].
 int setGreen(int color, int value) =>
     (color & 0xffff00ff) | (clamp255(value) << 8);

 /// Get the red channel from the [color].
 int getRed(int color) => (color >> 16) & 0xff;

 /// Returns a new color where the red channel of [color] has been replaced
 /// by [value].
 int setRed(int color, int value) =>
     (color & 0xff00ffff) | (clamp255(value) << 16);

 /// Get the alpha channel from the [color].
 int getAlpha(int color) => (color >> 24) & 0xff;

 /// Returns a new color where the alpha channel of [color] has been replaced
 /// by [value].
 int setAlpha(int color, int value) =>
     (color & 0x00ffffff) | (clamp255(value) << 24);

 /// Returns a new color of [src] alpha-blended onto [dst]. The opacity of [src]
 /// is additionally scaled by [fraction] / 255.
 int alphaBlendColors(int dst, int src, [int fraction = 0xff]) {
   double a = (getAlpha(src) / 255.0);
   if (fraction != 0xff) {
     a *= (fraction / 255.0);
   }

   int sr = (getRed(src) * a).round();
   int sg = (getGreen(src) * a).round();
   int sb = (getBlue(src) * a).round();
   int sa = (getAlpha(src) * a).round();

   int dr = (getRed(dst) * (1.0 - a)).round();
   int dg = (getGreen(dst) * (1.0 - a)).round();
   int db = (getBlue(dst) * (1.0 - a)).round();
   int da = (getAlpha(dst) * (1.0 - a)).round();

   return getColor(sr + dr, sg + dg, sb + db, sa + da);
 }

 /// Returns the luminance (grayscale) value of the [color].
 int getLuminance(int color) {
   int r = getRed(color);
   int g = getGreen(color);
   int b = getBlue(color);
   return (0.299 * r + 0.587 * g + 0.114 * b).round();
 }

 /// Returns the luminance (grayscale) value of the color.
 int getLuminanceRGB(int r, int g, int b) =>
     (0.299 * r + 0.587 * g + 0.114 * b).round();

 /// Convert an HSL color to RGB, where h is specified in normalized degrees
 /// [0, 1] (where 1 is 360-degrees); s and l are in the range [0, 1].
 /// Returns a list [r, g, b] with values in the range [0, 255].
 List<int> hslToRGB(num hue, num saturation, num lightness) {
   if (saturation == 0) {
     int gray = (lightness * 255.0).toInt();
     return [gray, gray, gray];
   }

   hue2rgb(num p, num q, num t) {
     if (t < 0.0) {
       t += 1.0;
     }
     if (t > 1) {
       t -= 1.0;
     }
     if (t < 1.0 / 6.0) {
       return p + (q - p) * 6.0 * t;
     }
     if (t < 1.0 / 2.0) {
       return q;
     }
     if (t < 2.0 / 3.0) {
       return p + (q - p) * (2.0 / 3.0 - t) * 6.0;
     }
     return p;
   }

   var q = lightness < 0.5
       ? lightness * (1.0 + saturation)
       : lightness + saturation - lightness * saturation;
   var p = 2.0 * lightness - q;

   var r = hue2rgb(p, q, hue + 1.0 / 3.0);
   var g = hue2rgb(p, q, hue);
   var b = hue2rgb(p, q, hue - 1.0 / 3.0);

   return [(r * 255.0).round(), (g * 255.0).round(), (b * 255.0).round()];
 }

 /// Convert an HSV color to RGB, where h is specified in normalized degrees
 /// [0, 1] (where 1 is 360-degrees); s and l are in the range [0, 1].
 /// Returns a list [r, g, b] with values in the range [0, 255].
 List<int> hsvToRGB(num hue, num saturation, num brightness) {
   if (saturation == 0) {
     var gray = (brightness * 255.0).round();
     return [gray, gray, gray];
   }

   num h = (hue - hue.floor()) * 6.0;
   num f = h - h.floor();
   num p = brightness * (1.0 - saturation);
   num q = brightness * (1.0 - saturation * f);
   num t = brightness * (1.0 - (saturation * (1.0 - f)));

   switch (h.toInt()) {
     case 0:
       return [
         (brightness * 255.0).round(),
         (t * 255.0).round(),
         (p * 255.0).round()
       ];
     case 1:
       return [
         (q * 255.0).round(),
         (brightness * 255.0).round(),
         (p * 255.0).round()
       ];
     case 2:
       return [
         (p * 255.0).round(),
         (brightness * 255.0).round(),
         (t * 255.0).round()
       ];
     case 3:
       return [
         (p * 255.0).round(),
         (q * 255.0).round(),
         (brightness * 255.0).round()
       ];
     case 4:
       return [
         (t * 255.0).round(),
         (p * 255.0).round(),
         (brightness * 255.0).round()
       ];
     case 5:
       return [
         (brightness * 255.0).round(),
         (p * 255.0).round(),
         (q * 255.0).round()
       ];
     default:
       throw new ImageException('invalid hue');
   }
 }

 /// Convert an RGB color to HSL, where r, g and b are in the range [0, 255].
 /// Returns a list [h, s, l] with values in the range [0, 1].
 List<num> rgbToHSL(num r, num g, num b) {
   r /= 255.0;
   g /= 255.0;
   b /= 255.0;
   var mx = max(r, max(g, b));
   var mn = min(r, min(g, b));
   num h;
   var l = (mx + mn) / 2.0;

   if (mx == mn) {
     return [0.0, 0.0, l];
   }

   var d = mx - mn;

   var s = l > 0.5 ? d / (2.0 - mx - mn) : d / (mx + mn);

   if (mx == r) {
     h = (g - b) / d + (g < b ? 6.0 : 0.0);
   } else if (mx == g) {
     h = (b - r) / d + 2.0;
   } else {
     h = (r - g) / d + 4.0;
   }

   h /= 6.0;

   return [h, s, l];
 }

 /// Convert a CIE-L*ab color to XYZ.
 List<int> labToXYZ(num l, num a, num b) {
   num y = (l + 16.0) / 116.0;
   num x = y + (a / 500.0);
   num z = y - (b / 200.0);
   if (pow(x, 3) > 0.008856) {
     x = pow(x, 3);
   } else {
     x = (x - 16.0 / 116) / 7.787;
   }
   if (pow(y, 3) > 0.008856) {
     y = pow(y, 3);
   } else {
     y = (y - 16.0 / 116.0) / 7.787;
   }
   if (pow(z, 3) > 0.008856) {
     z = pow(z, 3);
   } else {
     z = (z - 16.0 / 116.0) / 7.787;
   }

   return [(x * 95.047).toInt(), (y * 100.0).toInt(), (z * 108.883).toInt()];
 }

 /// Convert an XYZ color to RGB.
 List<int> xyzToRGB(num x, num y, num z) {
   x /= 100;
   y /= 100;
   z /= 100;
   num r = (3.2406 * x) + (-1.5372 * y) + (-0.4986 * z);
   num g = (-0.9689 * x) + (1.8758 * y) + (0.0415 * z);
   num b = (0.0557 * x) + (-0.2040 * y) + (1.0570 * z);
   if (r > 0.0031308) {
     r = (1.055 * pow(r, 0.4166666667)) - 0.055;
   } else {
     r *= 12.92;
   }
   if (g > 0.0031308) {
     g = (1.055 * pow(g, 0.4166666667)) - 0.055;
   } else {
     g *= 12.92;
   }
   if (b > 0.0031308) {
     b = (1.055 * pow(b, 0.4166666667)) - 0.055;
   } else {
     b *= 12.92;
   }

   return [
     (r * 255).clamp(0, 255).toInt(),
     (g * 255).clamp(0, 255).toInt(),
     (b * 255).clamp(0, 255).toInt()
   ];
 }

 /// Convert a CMYK color to RGB, where c, m, y, k values are in the range
 /// [0, 255]. Returns a list [r, g, b] with values in the range [0, 255].
 List<int> cmykToRGB(num c, num m, num y, num k) {
   c /= 255.0;
   m /= 255.0;
   y /= 255.0;
   k /= 255.0;
   return [
     (255.0 * (1.0 - c) * (1.0 - k)).round(),
     (255.0 * (1.0 - m) * (1.0 - k)).round(),
     (255.0 * (1.0 - y) * (1.0 - k)).round()
   ];
 }

 /// Convert a CIE-L*ab color to RGB.
 List<int> labToRGB(num l, num a, num b) {
   const num ref_x = 95.047;
   const num ref_y = 100.000;
   const num ref_z = 108.883;

   num y = (l + 16.0) / 116.0;
   num x = a / 500.0 + y;
   num z = y - b / 200.0;

   num y3 = pow(y, 3);
   if (y3 > 0.008856) {
     y = y3;
   } else {
     y = (y - 16 / 116) / 7.787;
   }

   num x3 = pow(x, 3);
   if (x3 > 0.008856) {
     x = x3;
   } else {
     x = (x - 16 / 116) / 7.787;
   }

   num z3 = pow(z, 3);
   if (z3 > 0.008856) {
     z = z3;
   } else {
     z = (z - 16 / 116) / 7.787;
   }

   x *= ref_x;
   y *= ref_y;
   z *= ref_z;

   x /= 100.0;
   y /= 100.0;
   z /= 100.0;

   // xyz to rgb
   num R = x * 3.2406 + y * (-1.5372) + z * (-0.4986);
   num G = x * (-0.9689) + y * 1.8758 + z * 0.0415;
   num B = x * 0.0557 + y * (-0.2040) + z * 1.0570;

   if (R > 0.0031308) {
     R = 1.055 * (pow(R, 1.0 / 2.4)) - 0.055;
   } else {
     R = 12.92 * R;
   }

   if (G > 0.0031308) {
     G = 1.055 * (pow(G, 1.0 / 2.4)) - 0.055;
   } else {
     G = 12.92 * G;
   }

   if (B > 0.0031308) {
     B = 1.055 * (pow(B, 1.0 / 2.4)) - 0.055;
   } else {
     B = 12.92 * B;
   }

   return [
     (R * 255.0).clamp(0, 255).toInt(),
     (G * 255.0).clamp(0, 255).toInt(),
     (B * 255.0).clamp(0, 255).toInt()
   ];
 }

 /// Convert a RGB color to XYZ.
 List<num> rgbToXYZ(num r, num g, num b) {
   r = r / 255.0;
   g = g / 255.0;
   b = b / 255.0;

   if (r > 0.04045) {
     r = pow((r + 0.055) / 1.055, 2.4);
   } else {
     r = r / 12.92;
   }
   if (g > 0.04045) {
     g = pow((g + 0.055) / 1.055, 2.4);
   } else {
     g = g / 12.92;
   }
   if (b > 0.04045) {
     b = pow((b + 0.055) / 1.055, 2.4);
   } else {
     b = b / 12.92;
   }

   r = r * 100.0;
   g = g * 100.0;
   b = b * 100.0;

   return [
     r * 0.4124 + g * 0.3576 + b * 0.1805,
     r * 0.2126 + g * 0.7152 + b * 0.0722,
     r * 0.0193 + g * 0.1192 + b * 0.9505
   ];
 }

 /// Convert a XYZ color to CIE-L*ab.
 List<num> xyzToLab(num x, num y, num z) {
   x = x / 95.047;
   y = y / 100.0;
   z = z / 108.883;

   if (x > 0.008856) {
     x = pow(x, 1 / 3.0);
   } else {
     x = (7.787 * x) + (16 / 116.0);
   }
   if (y > 0.008856) {
     y = pow(y, 1 / 3.0);
   } else {
     y = (7.787 * y) + (16 / 116.0);
   }
   if (z > 0.008856) {
     z = pow(z, 1 / 3.0);
   } else {
     z = (7.787 * z) + (16 / 116.0);
   }

   return [(116.0 * y) - 16, 500.0 * (x - y), 200.0 * (y - z)];
 }

 /// Convert a RGB color to CIE-L*ab.
 List<num> rgbToLab(num r, num g, num b) {
   r = r / 255.0;
   g = g / 255.0;
   b = b / 255.0;

   if (r > 0.04045) {
     r = pow((r + 0.055) / 1.055, 2.4);
   } else {
     r = r / 12.92;
   }
   if (g > 0.04045) {
     g = pow((g + 0.055) / 1.055, 2.4);
   } else {
     g = g / 12.92;
   }
   if (b > 0.04045) {
     b = pow((b + 0.055) / 1.055, 2.4);
   } else {
     b = b / 12.92;
   }

   r = r * 100.0;
   g = g * 100.0;
   b = b * 100.0;

   num x = r * 0.4124 + g * 0.3576 + b * 0.1805;
   num y = r * 0.2126 + g * 0.7152 + b * 0.0722;
   num z = r * 0.0193 + g * 0.1192 + b * 0.9505;

   x = x / 95.047;
   y = y / 100.0;
   z = z / 108.883;

   if (x > 0.008856) {
     x = pow(x, 1 / 3.0);
   } else {
     x = (7.787 * x) + (16 / 116.0);
   }
   if (y > 0.008856) {
     y = pow(y, 1 / 3.0);
   } else {
     y = (7.787 * y) + (16 / 116.0);
   }
   if (z > 0.008856) {
     z = pow(z, 1 / 3.0);
   } else {
     z = (7.787 * z) + (16 / 116.0);
   }

   return [(116.0 * y) - 16, 500.0 * (x - y), 200.0 * (y - z)];
 }
	import 'dart:math';

	import 'image_exception.dart';
	import 'internal/clamp.dart';

	/// Image pixel colors are instantiated as an int object rather than an instance
	/// of the Color class in order to reduce object allocations. Image pixels are
	/// stored in 32-bit RGBA format (8 bits per channel). Internally in dart, this
	/// will be stored in a "small integer" on 64-bit machines, or a
	/// "medium integer" on 32-bit machines. In Javascript, this will be stored
	/// in a 64-bit double.
	///
	/// The Color class is used as a namespace for color operations, in an attempt
	/// to create a cleaner API for color operations.
	class Color {
	/// Create a color value from RGB values in the range [0, 255].
	static int fromRgb(int red, int green, int blue) {
	return getColor(red, green, blue);
	}

	/// Create a color value from RGBA values in the range [0, 255].
	static int fromRgba(int red, int green, int blue, int alpha) {
	return getColor(red, green, blue, alpha);
	}

	/// Create a color value from HSL values in the range [0, 1].
	static int fromHsl(num hue, num saturation, num lightness) {
	var rgb = hslToRGB(hue, saturation, lightness);
	return getColor(rgb[0], rgb[1], rgb[2]);
	}

	/// Create a color value from HSV values in the range [0, 1].
	static int fromHsv(num hue, num saturation, num value) {
	var rgb = hsvToRGB(hue, saturation, value);
	return getColor(rgb[0], rgb[1], rgb[2]);
	}

	/// Create a color value from XYZ values.
	static int fromXyz(num x, num y, num z) {
	var rgb = xyzToRGB(x, y, z);
	return getColor(rgb[0], rgb[1], rgb[2]);
	}

	/// Create a color value from CIE-L*ab values.
	static int fromLab(num L, num a, num b) {
	var rgb = labToRGB(L, a, b);
	return getColor(rgb[0], rgb[1], rgb[2]);
	}

	/// Compare colors from a 3 or 4 dimensional color space
	static num distance(List<num> c1, List<num> c2, bool compareAlpha) {
	num d1 = c1[0] - c2[0];
	num d2 = c1[1] - c2[1];
	num d3 = c1[2] - c2[2];
	if (compareAlpha) {
	num dA = c1[3] - c2[3];
	return sqrt(max(d1 * d1, (d1 - dA) * (d1 - dA)) +
	max(d2 * d2, (d2 - dA) * (d2 - dA)) +
	max(d3 * d3, (d3 - dA) * (d3 - dA)));
	} else {
	return sqrt(d1 * d1 + d2 * d2 + d3 * d3);
	}
	}
	}

	/// Blue channel of a color.
	const int BLUE = 0;

	/// Green channel of a color.
	const int GREEN = 1;

	/// Red channel of a color.
	const int RED = 2;

	/// Alpha channel of a color.
	const int ALPHA = 3;

	/// Luminance of a color.
	const int LUMINANCE = 4;

	/// Get the color with the given [r], [g], [b], and [a] components.
	///
	/// The channel order of a uint32 encoded color is RGBA, to be consistent
	/// with the image data of a canvas html element.
	int getColor(int r, int g, int b, [int a = 255]) =>
	(clamp255(a) << 24) \|
	(clamp255(r) << 16) \|
	(clamp255(g) << 8) \|
	(clamp255(b));

	/// Get the [channel] from the [color].
	int getChannel(int color, int channel) => channel == RED
	? getRed(color)
	: channel == GREEN
	? getGreen(color)
	: channel == BLUE ? getBlue(color) : getAlpha(color);

	/// Returns a new color, where the given [color]'s [channel] has been
	/// replaced with the given [value].
	int setChannel(int color, int channel, int value) => channel == RED
	? setRed(color, value)
	: channel == GREEN
	? setGreen(color, value)
	: channel == BLUE ? setBlue(color, value) : setAlpha(color, value);

	/// Get the blue channel from the [color].
	int getBlue(int color) => (color) & 0xff;

	/// Returns a new color where the blue channel of [color] has been replaced
	/// by [value].
	int setBlue(int color, int value) => (color & 0xffffff00) \| (clamp255(value));

	/// Get the green channel from the [color].
	int getGreen(int color) => (color >> 8) & 0xff;

	/// Returns a new color where the green channel of [color] has been replaced
	/// by [value].
	int setGreen(int color, int value) =>
	(color & 0xffff00ff) \| (clamp255(value) << 8);

	/// Get the red channel from the [color].
	int getRed(int color) => (color >> 16) & 0xff;

	/// Returns a new color where the red channel of [color] has been replaced
	/// by [value].
	int setRed(int color, int value) =>
	(color & 0xff00ffff) \| (clamp255(value) << 16);

	/// Get the alpha channel from the [color].
	int getAlpha(int color) => (color >> 24) & 0xff;

	/// Returns a new color where the alpha channel of [color] has been replaced
	/// by [value].
	int setAlpha(int color, int value) =>
	(color & 0x00ffffff) \| (clamp255(value) << 24);

	/// Returns a new color of [src] alpha-blended onto [dst]. The opacity of [src]
	/// is additionally scaled by [fraction] / 255.
	int alphaBlendColors(int dst, int src, [int fraction = 0xff]) {
	double a = (getAlpha(src) / 255.0);
	if (fraction != 0xff) {
	a *= (fraction / 255.0);
	}

	int sr = (getRed(src) * a).round();
	int sg = (getGreen(src) * a).round();
	int sb = (getBlue(src) * a).round();
	int sa = (getAlpha(src) * a).round();

	int dr = (getRed(dst) * (1.0 - a)).round();
	int dg = (getGreen(dst) * (1.0 - a)).round();
	int db = (getBlue(dst) * (1.0 - a)).round();
	int da = (getAlpha(dst) * (1.0 - a)).round();

	return getColor(sr + dr, sg + dg, sb + db, sa + da);
	}

	/// Returns the luminance (grayscale) value of the [color].
	int getLuminance(int color) {
	int r = getRed(color);
	int g = getGreen(color);
	int b = getBlue(color);
	return (0.299 * r + 0.587 * g + 0.114 * b).round();
	}

	/// Returns the luminance (grayscale) value of the color.
	int getLuminanceRGB(int r, int g, int b) =>
	(0.299 * r + 0.587 * g + 0.114 * b).round();

	/// Convert an HSL color to RGB, where h is specified in normalized degrees
	/// [0, 1] (where 1 is 360-degrees); s and l are in the range [0, 1].
	/// Returns a list [r, g, b] with values in the range [0, 255].
	List<int> hslToRGB(num hue, num saturation, num lightness) {
	if (saturation == 0) {
	int gray = (lightness * 255.0).toInt();
	return [gray, gray, gray];
	}

	hue2rgb(num p, num q, num t) {
	if (t < 0.0) {
	t += 1.0;
	}
	if (t > 1) {
	t -= 1.0;
	}
	if (t < 1.0 / 6.0) {
	return p + (q - p) * 6.0 * t;
	}
	if (t < 1.0 / 2.0) {
	return q;
	}
	if (t < 2.0 / 3.0) {
	return p + (q - p) * (2.0 / 3.0 - t) * 6.0;
	}
	return p;
	}

	var q = lightness < 0.5
	? lightness * (1.0 + saturation)
	: lightness + saturation - lightness * saturation;
	var p = 2.0 * lightness - q;

	var r = hue2rgb(p, q, hue + 1.0 / 3.0);
	var g = hue2rgb(p, q, hue);
	var b = hue2rgb(p, q, hue - 1.0 / 3.0);

	return [(r * 255.0).round(), (g * 255.0).round(), (b * 255.0).round()];
	}

	/// Convert an HSV color to RGB, where h is specified in normalized degrees
	/// [0, 1] (where 1 is 360-degrees); s and l are in the range [0, 1].
	/// Returns a list [r, g, b] with values in the range [0, 255].
	List<int> hsvToRGB(num hue, num saturation, num brightness) {
	if (saturation == 0) {
	var gray = (brightness * 255.0).round();
	return [gray, gray, gray];
	}

	num h = (hue - hue.floor()) * 6.0;
	num f = h - h.floor();
	num p = brightness * (1.0 - saturation);
	num q = brightness * (1.0 - saturation * f);
	num t = brightness * (1.0 - (saturation * (1.0 - f)));

	switch (h.toInt()) {
	case 0:
	return [
	(brightness * 255.0).round(),
	(t * 255.0).round(),
	(p * 255.0).round()
	];
	case 1:
	return [
	(q * 255.0).round(),
	(brightness * 255.0).round(),
	(p * 255.0).round()
	];
	case 2:
	return [
	(p * 255.0).round(),
	(brightness * 255.0).round(),
	(t * 255.0).round()
	];
	case 3:
	return [
	(p * 255.0).round(),
	(q * 255.0).round(),
	(brightness * 255.0).round()
	];
	case 4:
	return [
	(t * 255.0).round(),
	(p * 255.0).round(),
	(brightness * 255.0).round()
	];
	case 5:
	return [
	(brightness * 255.0).round(),
	(p * 255.0).round(),
	(q * 255.0).round()
	];
	default:
	throw new ImageException('invalid hue');
	}
	}

	/// Convert an RGB color to HSL, where r, g and b are in the range [0, 255].
	/// Returns a list [h, s, l] with values in the range [0, 1].
	List<num> rgbToHSL(num r, num g, num b) {
	r /= 255.0;
	g /= 255.0;
	b /= 255.0;
	var mx = max(r, max(g, b));
	var mn = min(r, min(g, b));
	num h;
	var l = (mx + mn) / 2.0;

	if (mx == mn) {
	return [0.0, 0.0, l];
	}

	var d = mx - mn;

	var s = l > 0.5 ? d / (2.0 - mx - mn) : d / (mx + mn);

	if (mx == r) {
	h = (g - b) / d + (g < b ? 6.0 : 0.0);
	} else if (mx == g) {
	h = (b - r) / d + 2.0;
	} else {
	h = (r - g) / d + 4.0;
	}

	h /= 6.0;

	return [h, s, l];
	}

	/// Convert a CIE-L*ab color to XYZ.
	List<int> labToXYZ(num l, num a, num b) {
	num y = (l + 16.0) / 116.0;
	num x = y + (a / 500.0);
	num z = y - (b / 200.0);
	if (pow(x, 3) > 0.008856) {
	x = pow(x, 3);
	} else {
	x = (x - 16.0 / 116) / 7.787;
	}
	if (pow(y, 3) > 0.008856) {
	y = pow(y, 3);
	} else {
	y = (y - 16.0 / 116.0) / 7.787;
	}
	if (pow(z, 3) > 0.008856) {
	z = pow(z, 3);
	} else {
	z = (z - 16.0 / 116.0) / 7.787;
	}

	return [(x * 95.047).toInt(), (y * 100.0).toInt(), (z * 108.883).toInt()];
	}

	/// Convert an XYZ color to RGB.
	List<int> xyzToRGB(num x, num y, num z) {
	x /= 100;
	y /= 100;
	z /= 100;
	num r = (3.2406 * x) + (-1.5372 * y) + (-0.4986 * z);
	num g = (-0.9689 * x) + (1.8758 * y) + (0.0415 * z);
	num b = (0.0557 * x) + (-0.2040 * y) + (1.0570 * z);
	if (r > 0.0031308) {
	r = (1.055 * pow(r, 0.4166666667)) - 0.055;
	} else {
	r *= 12.92;
	}
	if (g > 0.0031308) {
	g = (1.055 * pow(g, 0.4166666667)) - 0.055;
	} else {
	g *= 12.92;
	}
	if (b > 0.0031308) {
	b = (1.055 * pow(b, 0.4166666667)) - 0.055;
	} else {
	b *= 12.92;
	}

	return [
	(r * 255).clamp(0, 255).toInt(),
	(g * 255).clamp(0, 255).toInt(),
	(b * 255).clamp(0, 255).toInt()
	];
	}

	/// Convert a CMYK color to RGB, where c, m, y, k values are in the range
	/// [0, 255]. Returns a list [r, g, b] with values in the range [0, 255].
	List<int> cmykToRGB(num c, num m, num y, num k) {
	c /= 255.0;
	m /= 255.0;
	y /= 255.0;
	k /= 255.0;
	return [
	(255.0 * (1.0 - c) * (1.0 - k)).round(),
	(255.0 * (1.0 - m) * (1.0 - k)).round(),
	(255.0 * (1.0 - y) * (1.0 - k)).round()
	];
	}

	/// Convert a CIE-L*ab color to RGB.
	List<int> labToRGB(num l, num a, num b) {
	const num ref_x = 95.047;
	const num ref_y = 100.000;
	const num ref_z = 108.883;

	num y = (l + 16.0) / 116.0;
	num x = a / 500.0 + y;
	num z = y - b / 200.0;

	num y3 = pow(y, 3);
	if (y3 > 0.008856) {
	y = y3;
	} else {
	y = (y - 16 / 116) / 7.787;
	}

	num x3 = pow(x, 3);
	if (x3 > 0.008856) {
	x = x3;
	} else {
	x = (x - 16 / 116) / 7.787;
	}

	num z3 = pow(z, 3);
	if (z3 > 0.008856) {
	z = z3;
	} else {
	z = (z - 16 / 116) / 7.787;
	}

	x *= ref_x;
	y *= ref_y;
	z *= ref_z;

	x /= 100.0;
	y /= 100.0;
	z /= 100.0;

	// xyz to rgb
	num R = x * 3.2406 + y * (-1.5372) + z * (-0.4986);
	num G = x * (-0.9689) + y * 1.8758 + z * 0.0415;
	num B = x * 0.0557 + y * (-0.2040) + z * 1.0570;

	if (R > 0.0031308) {
	R = 1.055 * (pow(R, 1.0 / 2.4)) - 0.055;
	} else {
	R = 12.92 * R;
	}

	if (G > 0.0031308) {
	G = 1.055 * (pow(G, 1.0 / 2.4)) - 0.055;
	} else {
	G = 12.92 * G;
	}

	if (B > 0.0031308) {
	B = 1.055 * (pow(B, 1.0 / 2.4)) - 0.055;
	} else {
	B = 12.92 * B;
	}

	return [
	(R * 255.0).clamp(0, 255).toInt(),
	(G * 255.0).clamp(0, 255).toInt(),
	(B * 255.0).clamp(0, 255).toInt()
	];
	}

	/// Convert a RGB color to XYZ.
	List<num> rgbToXYZ(num r, num g, num b) {
	r = r / 255.0;
	g = g / 255.0;
	b = b / 255.0;

	if (r > 0.04045) {
	r = pow((r + 0.055) / 1.055, 2.4);
	} else {
	r = r / 12.92;
	}
	if (g > 0.04045) {
	g = pow((g + 0.055) / 1.055, 2.4);
	} else {
	g = g / 12.92;
	}
	if (b > 0.04045) {
	b = pow((b + 0.055) / 1.055, 2.4);
	} else {
	b = b / 12.92;
	}

	r = r * 100.0;
	g = g * 100.0;
	b = b * 100.0;

	return [
	r * 0.4124 + g * 0.3576 + b * 0.1805,
	r * 0.2126 + g * 0.7152 + b * 0.0722,
	r * 0.0193 + g * 0.1192 + b * 0.9505
	];
	}

	/// Convert a XYZ color to CIE-L*ab.
	List<num> xyzToLab(num x, num y, num z) {
	x = x / 95.047;
	y = y / 100.0;
	z = z / 108.883;

	if (x > 0.008856) {
	x = pow(x, 1 / 3.0);
	} else {
	x = (7.787 * x) + (16 / 116.0);
	}
	if (y > 0.008856) {
	y = pow(y, 1 / 3.0);
	} else {
	y = (7.787 * y) + (16 / 116.0);
	}
	if (z > 0.008856) {
	z = pow(z, 1 / 3.0);
	} else {
	z = (7.787 * z) + (16 / 116.0);
	}

	return [(116.0 * y) - 16, 500.0 * (x - y), 200.0 * (y - z)];
	}

	/// Convert a RGB color to CIE-L*ab.
	List<num> rgbToLab(num r, num g, num b) {
	r = r / 255.0;
	g = g / 255.0;
	b = b / 255.0;

	if (r > 0.04045) {
	r = pow((r + 0.055) / 1.055, 2.4);
	} else {
	r = r / 12.92;
	}
	if (g > 0.04045) {
	g = pow((g + 0.055) / 1.055, 2.4);
	} else {
	g = g / 12.92;
	}
	if (b > 0.04045) {
	b = pow((b + 0.055) / 1.055, 2.4);
	} else {
	b = b / 12.92;
	}

	r = r * 100.0;
	g = g * 100.0;
	b = b * 100.0;

	num x = r * 0.4124 + g * 0.3576 + b * 0.1805;
	num y = r * 0.2126 + g * 0.7152 + b * 0.0722;
	num z = r * 0.0193 + g * 0.1192 + b * 0.9505;

	x = x / 95.047;
	y = y / 100.0;
	z = z / 108.883;

	if (x > 0.008856) {
	x = pow(x, 1 / 3.0);
	} else {
	x = (7.787 * x) + (16 / 116.0);
	}
	if (y > 0.008856) {
	y = pow(y, 1 / 3.0);
	} else {
	y = (7.787 * y) + (16 / 116.0);
	}
	if (z > 0.008856) {
	z = pow(z, 1 / 3.0);
	} else {
	z = (7.787 * z) + (16 / 116.0);
	}

	return [(116.0 * y) - 16, 500.0 * (x - y), 200.0 * (y - z)];
	}