[转]是把一张图片中除白色之外的其他像素都变为黑色
查API的时候查到一个ColorTransform类，觉得这个类应该可以完成我需要的功能，不过现在还是想不到应该怎么样才能实现这个需求
哈哈，谢谢！
功能实现了，经你一提醒，我试了一下把MC的饱和度和亮度都设为－100，差不多就是我想要的效果
代码如下：
var color:ColorMatrix = new ColorMatrix();color.adjustSaturation(-100);color.adjustBrightness(-100);mc.filters = [new ColorMatrixFilter(color)];以下是ColorMatrix类（此类是他人作品，使用请加上作者信息，谢谢！）:/*** ColorMatrix by Grant Skinner. August 8, 2005* Updated to AS3 November 19, 2007* Visit www.gskinner.com/blog for documentation, updates and more free code.** You may distribute this class freely, provided it is not modified in any way (including* removing this header or changing the package path).** Please contact info@gskinner.com prior to distributing modified versions of this class.*usage:http://www.gskinner.com/blog/archives/2005/09/flash_8_source.html*var cm = new ColorMatrix();* cm.adjustColor(20,20,20,20);*displayObject.filters = [new ColorMatrixFilter(cm)];*/package { dynamic public class ColorMatrix extends Array {// constant for contrast calculations: private static const DELTA_INDEX:Array = [ 0, 0.01, 0.02, 0.04, 0.05, 0.06, 0.07, 0.08, 0.1, 0.11, 0.12, 0.14, 0.15, 0.16, 0.17, 0.18, 0.20, 0.21, 0.22, 0.24, 0.25, 0.27, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38, 0.40, 0.42, 0.44, 0.46, 0.48, 0.5, 0.53, 0.56, 0.59, 0.62, 0.65, 0.68, 0.71, 0.74, 0.77, 0.80, 0.83, 0.86, 0.89, 0.92, 0.95, 0.98, 1.0, 1.06, 1.12, 1.18, 1.24, 1.30, 1.36, 1.42, 1.48, 1.54, 1.60, 1.66, 1.72, 1.78, 1.84, 1.90, 1.96, 2.0, 2.12, 2.25, 2.37, 2.50, 2.62, 2.75, 2.87, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.3, 4.7, 4.9, 5.0, 5.5, 6.0, 6.5, 6.8, 7.0, 7.3, 7.5, 7.8, 8.0, 8.4, 8.7, 9.0, 9.4, 9.6, 9.8, 10.0 ]; // identity matrix constant: private static const IDENTITY_MATRIX:Array = [ 1,0,0,0,0, 0,1,0,0,0, 0,0,1,0,0, 0,0,0,1,0, 0,0,0,0,1 ]; private static const LENGTH:Number = IDENTITY_MATRIX.length;// initialization: public function ColorMatrix(p_matrix:Array = null) { p_matrix = fixMatrix(p_matrix); copyMatrix(((p_matrix.length == LENGTH) ? p_matrix : IDENTITY_MATRIX)); }// public methods: public function reset():void { for (var i:uint = 0; i < LENGTH; i++) { this[i] = IDENTITY_MATRIX[i]; } } public function adjustColor(p_brightness:Number, p_contrast:Number, p_saturation:Number, p_hue:Number):void { adjustHue(p_hue); adjustContrast(p_contrast); adjustBrightness(p_brightness); adjustSaturation(p_saturation); } public function adjustBrightness(p_val:Number):void { p_val = cleanValue(p_val, 100); if (p_val == 0 || isNaN(p_val)) { return; } multiplyMatrix([ 1,0,0,0,p_val, 0,1,0,0,p_val, 0,0,1,0,p_val, 0,0,0,1,0, 0,0,0,0,1 ]); } public function adjustContrast(p_val:Number):void { p_val = cleanValue(p_val, 100); if (p_val == 0 || isNaN(p_val)) { return; } var x:Number; if (p_val < 0) { x = 127 + p_val / 100 * 127; } else { x = p_val % 1; if (x == 0) { x = DELTA_INDEX[p_val]; } else { //x = DELTA_INDEX[(p_val<<0)]; // this is how the IDE does it. x = DELTA_INDEX[(p_val << 0)] * (1 - x) + DELTA_INDEX[(p_val << 0) + 1] * x; // use linear interpolation for more granularity. } x = x * 127 + 127; } multiplyMatrix([ x/127,0,0,0,0.5*(127-x), 0,x/127,0,0,0.5*(127-x), 0,0,x/127,0,0.5*(127-x), 0,0,0,1,0, 0,0,0,0,1 ]); } public function adjustSaturation(p_val:Number):void { p_val = cleanValue(p_val, 100); if (p_val == 0 || isNaN(p_val)) { return; } var x:Number = 1 + ((p_val > 0) ? 3 * p_val / 100 : p_val / 100); var lumR:Number = 0.3086; var lumG:Number = 0.6094; var lumB:Number = 0.0820; multiplyMatrix([ lumR*(1-x)+x,lumG*(1-x),lumB*(1-x),0,0, lumR*(1-x),lumG*(1-x)+x,lumB*(1-x),0,0, lumR*(1-x),lumG*(1-x),lumB*(1-x)+x,0,0, 0,0,0,1,0, 0,0,0,0,1 ]); } public function adjustHue(p_val:Number):void { p_val = cleanValue(p_val, 180) / 180 * Math.PI; if (p_val == 0 || isNaN(p_val)) { return; } var cosVal:Number = Math.cos(p_val); var sinVal:Number = Math.sin(p_val); var lumR:Number = 0.213; var lumG:Number = 0.715; var lumB:Number = 0.072; multiplyMatrix([ lumR+cosVal*(1-lumR)+sinVal*(-lumR),lumG+cosVal*(-lumG)+sinVal*(-lumG),lumB+cosVal*(-lumB)+sinVal*(1-lumB),0,0, lumR+cosVal*(-lumR)+sinVal*(0.143),lumG+cosVal*(1-lumG)+sinVal*(0.140),lumB+cosVal*(-lumB)+sinVal*(-0.283),0,0, lumR+cosVal*(-lumR)+sinVal*(-(1-lumR)),lumG+cosVal*(-lumG)+sinVal*(lumG),lumB+cosVal*(1-lumB)+sinVal*(lumB),0,0, 0,0,0,1,0, 0,0,0,0,1 ]); } public function concat(p_matrix:Array):void { p_matrix = fixMatrix(p_matrix); if (p_matrix.length != LENGTH) { return; } multiplyMatrix(p_matrix); } public function clone():ColorMatrix { return new ColorMatrix(this); } public function toString():String { return "ColorMatrix [ " + this.join(" , ") + " ]"; } // return a length 20 array (5x4): public function toArray():Array { return slice(0, 20); }// private methods: // copy the specified matrix's values to this matrix: protected function copyMatrix(p_matrix:Array):void { var l:Number = LENGTH; for (var i:uint = 0; i < l; i++) { this[i] = p_matrix[i]; } } // multiplies one matrix against another: protected function multiplyMatrix(p_matrix:Array):void { var col:Array = []; for (var i:uint = 0; i < 5; i++) { for (var j:uint = 0; j < 5; j++) { col[j] = this[j + i * 5]; } for (j = 0; j < 5; j++) { var val:Number = 0; for (var k:Number = 0; k < 5; k++) { val += p_matrix[j + k * 5] * col[k]; } this[j + i * 5] = val; } } } // make sure values are within the specified range, hue has a limit of 180, others are 100: protected function cleanValue(p_val:Number, p_limit:Number):Number { return Math.min(p_limit, Math.max(-p_limit, p_val)); } // makes sure matrixes are 5x5 (25 long): protected function fixMatrix(p_matrix:Array = null):Array { if (p_matrix == null) { return IDENTITY_MATRIX; } if (p_matrix is ColorMatrix) { p_matrix = p_matrix.slice(0); } if (p_matrix.length < LENGTH) { p_matrix = p_matrix.slice(0, p_matrix.length).concat(IDENTITY_MATRIX.slice(p_matrix.length, LENGTH)); } else if (p_matrix.length > LENGTH) { p_matrix = p_matrix.slice(0, LENGTH); } return p_matrix; } }}