Different Color Averaging algorithms

Based on this blog post: http://asserttrue.blogspot.com/2008/10/fast-pixel-averaging.html

by Quasimondo 24 Jan 2011

• Related works: 2

Tags

average color optimization rgb
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/**
 * Copyright Quasimondo ( http://wonderfl.net/user/Quasimondo )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/lvsf
 */

package {
    import flash.display.Shape;
    import flash.display.Graphics;
    import flash.text.TextField;
    import flash.display.Sprite;
    
    public class ColorAveraging extends Sprite 
    {
        
        public function ColorAveraging()
        {
             var tf:TextField = new TextField();
             tf.autoSize = "left";
             tf..x = 130;
             var shp:Shape = new Shape();
             
             var g:Graphics = shp.graphics;
             
             for ( var i:int = 0; i < 50; i++ )
             {
                 var a:int = Math.random() * 0x1000000;
                 var b:int = Math.random() * 0x1000000;
                    
                 g.beginFill( a )
                 g.drawRect( 16,i*16,16,16 ); 
                 g.endFill();
                 
                 g.beginFill( b )
                 g.drawRect( 32,i*16,16,16 ); 
                 g.endFill();
                 
                 g.beginFill( avg1(a,b) )
                 g.drawRect( 60,i*16,16,16 ); 
                 g.endFill();
                 
                 g.beginFill( avg2(a,b) )
                 g.drawRect( 76,i*16,16,16 ); 
                 g.endFill();
                 
                 g.beginFill( avg3(a,b) )
                 g.drawRect( 92,i*16,16,16 ); 
                 g.endFill();
                 
                 g.beginFill( avg4(a,b) )
                 g.drawRect( 108,i*16,16,16 ); 
                 g.endFill();
                   
                 tf.appendText( a.toString(16)+" : "+b.toString(16)+" - "+avg1(a,b).toString(16) + " | "+avg2(a,b).toString(16) + " | "+ avg3(a,b).toString(16) + " | " + avg4(a,b).toString(16) + "\n");
             
             }

              addChild(shp);
              addChild(tf);
         }

        private function avg1( a:int, b: uint ):int
        {
              var REDMASK:int = 0xff0000;
              var GREENMASK:int = 0x0000ff00;
              var BLUEMASK:int = 0x000000ff;
              var aRed:int = a & REDMASK;
              var aGreen:int = a & GREENMASK;
              var aBlue:int = a & BLUEMASK;
              var bRed:int = b & REDMASK;
              var bGreen:int = b & GREENMASK;
              var bBlue :int= b & BLUEMASK;
    
              var aveRed :int= (aRed + bRed) >> 1;
              var aveGreen:int = (aGreen + bGreen) >> 1;
              var aveBlue:int = (aBlue + bBlue) >> 1;
       
              return (aveRed & REDMASK ) | (aveGreen & GREENMASK) | ( aveBlue & BLUEMASK );
          }
          
          private function avg2( a:int, b:int ):int
          { 
               var MASK7BITS:int = 0xfefeff; 
               a &= MASK7BITS;
               b &= MASK7BITS;  
              return (a+b)>>1;
          } 
          
          private function avg3( a:int, b:int ):int
          {
              var lowbits:int = (((a & 0x7f7f7f) + (b & 0x7f7f7f)) & 0xfefefe)
              var highbits:int = (a & 0x808080) + (b & 0x808080);
              return (lowbits + highbits) >> 1;
          } 
     
         private function avg4( a:int, b:int ):int
         {
             return ( a + b - ((a ^ b) & 0x10101)) >> 1
         }
     }
}