package
{ 
	import flash.geom.ColorTransform;
	public class ColorUtil
	{  		
		/**
		 * RGBColorTransform Create an instance of the information.
		 * @ Param rgb RGB integer value that indicates (0x000000 - 0xFFFFFF)
		 * @ Param amount of fill adaptive value (0.0 - 1.0)
		 * @ Param alpha transparency (0.0 - 1.0)
		 * @ Return a new instance ColorTransform
		 * */
		public static function colorTransform (rgb: uint = 0, amount: Number = 1.0, 
                                alpha: Number = 1.0): ColorTransform
		{
			amount = (amount> 1)? 1: (amount <0)? 0: amount;
			alpha = (alpha> 1)? 1: (alpha <0)? 0: alpha;
			var r: Number = ((rgb>> 16) & 0xff) * amount;
			var g: Number = ((rgb>> 8) & 0xff) * amount;
			var b: Number = (rgb & 0xff) * amount;
			var a: Number = 1-amount;
			return new ColorTransform (a, a, a, alpha, r, g, b, 0);
		}

		/**
		 * Subtraction.  
		 * 2 RGB single number that indicates (0x000000 0xFFFFFF up from) is subtracted 
                 * from the return numbers.
		 * @ Param col1 RGB numbers show (0x000000 0xFFFFFF up from)
		 * @ Param col2 RGB numbers show (0x000000 0xFFFFFF up from)
		 * @ Return value subtracted Blend 
		 **/
		public static function subtract (col1: uint, col2: uint): uint
		{
			var colA: Array = toRGB (col1);
			var colB: Array = toRGB (col2);
			var r: uint = Math.max (Math.max (colB [0] - (256-colA [0]), 
                                                                colA [0] - (256-colB [0])), 0);
			var g: uint = Math.max (Math.max (colB [1] - (256-colA [1]), 
                                                                colA [1] - (256-colB [1])), 0);
			var b: uint = Math.max (Math.max (colB [2] - (256-colA [2]), 
                                                                colA [2] - (256-colB [2])), 0);
			return r <<16 | g <<8 | b;
		}

		/**
		 * Additive color. 
		 * 2 RGB single number that indicates (0x000000 0xFFFFFF up from) Returns the value 
                 * of the additive mixture.
		 * @ Param col1 RGB numbers show (0x000000 0xFFFFFF up from)
		 * @ Param col2 RGB numbers show (0x000000 0xFFFFFF up from)
		 * @ Return the additive color
		 **/
		public static function sum (col1: uint, col2: uint): uint
		{
			var c1: Array = toRGB (col1);
			var c2: Array = toRGB (col2);
			var r: uint = Math.min (c1 [0] + c2 [0], 255);
			var g: uint = Math.min (c1 [1] + c2 [1], 255);
			var b: uint = Math.min (c1 [2] + c2 [2], 255);
			return r <<16 | g <<8 | b;
		}

		/**
		 * Subtractive. 
		 * 2 RGB single number that indicates (0x000000 0xFFFFFF up from) Returns the value 
                 * of the subtractive color.
		 * @ Param col1 RGB numbers show (0x000000 0xFFFFFF up from)
		 * @ Param col2 RGB numbers show (0x000000 0xFFFFFF up from)
		 * @ Return the subtractive
		 **/
		public static function sub (col1: uint, col2: uint): uint
		{
			var c1: Array = toRGB (col1);
			var c2: Array = toRGB (col2);
			var r: uint = Math.max (c1 [0]-c2 [0], 0);
			var g: uint = Math.max (c1 [1]-c2 [1], 0);
			var b: uint = Math.max (c1 [2]-c2 [2], 0);
			return r <<16 | g <<8 | b;
		}

		/**
		 * Comparison (dark). 
		 * 2 RGB single number that indicates (0x000000 0xFFFFFF up from) to compare,
                 * RGB lower combined returns a numeric value for each number.
		 * @ Param col1 RGB numbers show (0x000000 0xFFFFFF up from)
		 * @ Param col2 RGB numbers show (0x000000 0xFFFFFF up from)
		 * @ Return comparison (dark) values
		 **/
		public static function min (col1: uint, col2: uint): uint
		{
			var c1: Array = toRGB (col1);
			var c2: Array = toRGB (col2);
			var r: uint = Math.min (c1 [0], c2 [0]);
			var g: uint = Math.min (c1 [1], c2 [1]);
			var b: uint = Math.min (c1 [2], c2 [2]);
			return r <<16 | g <<8 | b;
		}

		/**
		 * Comparison (light). 
		 * 2 RGB single number that indicates (0x000000 0xFFFFFF up from) to compare, 
                 * RGB values combined with higher returns to their numbers.
		 * @ Param col1 RGB numbers show (0x000000 0xFFFFFF up from)
		 * @ Param col2 RGB numbers show (0x000000 0xFFFFFF up from)
		 * @ Return comparison (light) value
		 **/
		public static function max (col1: uint, col2: uint): uint
		{
			var c1: Array = toRGB (col1);
			var c2: Array = toRGB (col2);
			var r: uint = Math.max (c1 [0], c2 [0]);
			var g: uint = Math.max (c1 [1], c2 [1]);
			var b: uint = Math.max (c1 [2], c2 [2]);
			return r <<16 | g <<8 | b;
		}

		/**
		 *	Values calculated from each RGB * RGB color value.
		 * @ Param r the red (R) indicating the number (0-255)
		 * @ Param g green (G) indicates the number (0-255)
		 * @ Param b blue (B) shows the number (0-255)
		 * @ Return obtained from the RGB color value for each indicating the number
		 **/
		public static function rgb (r: uint, g: uint, b: uint): uint
		{
			return r <<16 | g <<8 | b;
		}

		/**
		 * HSV calculated from the numbers of each RGB color value.
		 * @ Param h hue (Hue) number that indicates (to 360-0)
		 * @ Param s the saturation (Saturation) shows the number (0.0 to 1.0)
		 * @ Param v lightness (Value) indicates the number (0.0 to 1.0)
		 * @ Return obtained from the RGB color value for each indicating the number
		 **/
		public static function hsv (h: int, s: Number, v: Number): uint
		{
			return rgb.apply (null, HSVtoRGB (h, s, v));
		}

		/**
		 * RGB figures show (0x000000 0xFFFFFF up from) the
		 * R, G, B returns an array divided into a number from 0 to 255, respectively.
		 *
		 * @ Param rgb RGB numbers show (0x000000 0xFFFFFF up from)
		 * @ Return array indicates the value of each color [R, G, B]
		 **/
		public static function toRGB (rgb: uint): Array
		{
			var r: uint = rgb>> 16 & 0xFF;
			var g: uint = rgb>> 8 & 0xFF;
			var b: uint = rgb & 0xFF;
			return [r, g, b];
		}

		/**
		 * RGB from the respective figures, HSV sequences in terms of returns.
		 * RGB values are as follows.
		 * R - a number from 0 to 255
		 * G - a number from 0 to 255
		 * B - a number from 0 to 255
		 *
		 * HSV values are as follows.
		 * H - a number between 360-0
		 * S - number between 0 and 1.0
		 * V - number between 0 and 1.0
		 *
		 * Can not compute, including alpha.
		 * @ Param r the red (R) indicating the number (0x00 to 0xFF to)
		 * @ Param g green (G) indicates the number (0x00 to 0xFF to)
		 * @ Param b blue (B) shows the number (0x00 to 0xFF to)
		 * @ Return HSV values into an array of [H, S, V]
		 **/
		public static function RGBtoHSV (r: Number, g: Number, b: Number): Array
		{
			r / = 255; g / = 255; b / = 255;
			var h: Number = 0, s: Number = 0, v: Number = 0;
			var x: Number, y: Number;
			if (r> = g) x = r; else x = g; if (b> x) x = b;
			if (r <= g) y = r; else y = g; if (b <y) y = b;
			v = x;
			var c: Number = xy;
			if (x == 0) s = 0; else s = c / x;
			if (s! = 0) {
				if (r == x) {
					h = (gb) / c;
				} else {
					if (g == x) {
						h = 2 + (br) / c;
					} Else {
						if (b == x) {
							h = 4 + (rg) / c;
						}
					}
				}
				h = h * 60;
				if (h <0) h = h +360;
			}
			return [h, s, v];
		}

                /**
		 * RGB from the respective figures, HSV sequences in terms of returns.
		 * RGB values are as follows.
		 * R - a number from 0 to 255
		 * G - a number from 0 to 255
		 * B - a number from 0 to 255
		 *
		 * CMYK values are as follows.
		 * C - a number between 0 to 255 representing cyan
		 * M - number between 0 to 255 representing magenta
		 * Y - number between 0 to 255 representing yellow
		 * K - number between 0 to 255 representing black
		 *
		 * Can not compute, including alpha.
		 * @ Param r the red (R) indicating the number (0x00 to 0xFF to)
		 * @ Param g green (G) indicates the number (0x00 to 0xFF to)
		 * @ Param b blue (B) shows the number (0x00 to 0xFF to)
		 * @ Return CMYK values into an array of [H, S, V] 
		 **/
		public static function RGBtoCMYK( r:Number, g:Number, b:Number ):Array
		{
			var c:Number=0, m:Number=0, y:Number=0, k:Number=0, z:Number=0;
			c = 255 – r;
			m = 255 – g;
			y = 255 – b;
			k = 255;

			if (c < k)
				k=c;
			if (m < k)
				k=m;
			if (y < k)
				k=y;
			if (k == 255)
			{
				c=0;
				m=0;
				y=0;
			}else
			{
				c=Math.round(255*(c-k)/(255-k));
				m=Math.round (255*(m-k)/(255-k));
				y=Math.round (255*(y-k)/(255-k));
			} 
			return [ c, m, y, k ];
		}
		/**
		 * HSV from each of the RGB values to determine a return as an array.
		 * RGB values are as follows.
		 * R - a number from 0 to 255
		 * G - a number from 0 to 255
		 * B - a number from 0 to 255
		 *
		 * HSV values are as follows.
		 * H - a number between 360-0
		 * S - number between 0 and 1.0
		 * V - number between 0 and 1.0
		 *
		 * H is replaced with equivalent numbers in the range of the 360-0 that is out of range.
		 * Can not compute, including alpha.
		 *
		 * @ Param h hue (Hue) number that indicates (to 360-0)
		 * @ Param s the saturation (Saturation) shows the number (0.0 to 1.0)
		 * @ Param v lightness (Value) indicates the number (0.0 to 1.0)
		 * @ Return RGB values into an array of [R, G, B]
		 **/
		public static function HSVtoRGB (h: Number, s: Number, v: Number): Array
		{
			var r: Number = 0, g: Number = 0, b: Number = 0;
			var i: Number, x: Number, y: Number, z: Number;
			if (s <0) s = 0; if (s> 1) s = 1; if (v <0) v = 0; if (v> 1) v = 1;
			h = h% 360; if (h <0) h + = 360; h / = 60;
			i = h>> 0;
			x = v * (1 - s); y = v * (1 - s * (h - i)); z = v * (1 - s * (1 - h + i));
			switch (i) {
				case 0: r = v; g = z; b = x; break;
				case 1: r = y; g = v; b = x; break;
				case 2: r = x; g = v; b = z; break;
				case 3: r = x; g = y; b = v; break;
				case 4: r = z; g = x; b = v; break;
				case 5: r = v; g = x; b = y; break;
			}
			return [r * 255>> 0, g * 255>> 0, b * 255>> 0];
		}
                /**
		 * RGB from each of the CMYK values to determine a return as an array.
		 * CMYK values are as follows.
		 * C - a number between 0 to 255 representing cyan
		 * M - number between 0 to 255 representing magenta
		 * Y - number between 0 to 255 representing yellow
		 * K - number between 0 to 255 representing black
		 * 
		 **/
		public static function CMYKtoRGB( c:Number, m:Number, y:Number, k:Number ):Array
                {
                	c = 255 - c;
                	m = 255 - m;
                	y = 255 - y;
                	k = 255 - k; 
                	return [(255 - c) * (255 - k) / 255, 
                                (255 - m) * (255 - k) / 255, (255 - y) * (255 - k) / 255)];
                }
	}
}

http://nsdevaraj.wordpress.com/2009/04/17/as3-color-utility-functions/

Full credit for this class goes to Deva Raj (@nsdevaraj). Many thanks.

AS3 ColorUtil Class (inc. RGBtoCMYK, CMYKtoRGB, subtractive colour & addative colour)

color, convert

ActionScript 3