2008
09.04

Flash 10’s BitmapData.histogram is really slow?

Category: AS3, Flash 10, Uncategorized / Tag: , , ,  / Add Comment

Author: Josh Chernoff

Josh Chernoff has wrote 79 articles for us.

I have been playing with BitmapData type and getPixelAt to make histograms. When I seen that the flash 10's BitmapData has a new method called histogram I thought it was a new improvement on analyzing BitmapData. Boy was I wrong. it's really really slow and I don't have clue why. Bug maybe??

Here's the code for any one who thinks it maybe that. Whats your thoughts?

FYI: with a for loop and getPixelAt I could still get 25fps at 1ms cycles. Though I have yet to see the frame rate for histogram, I cant event get close to a 1fps.

PLAIN TEXT
Actionscript:
  1. package
  2. {
  3.     import flash.display.BitmapData;
  4.     import flash.display.MovieClip;
  5.     import flash.display.Shape;
  6.     import flash.display.Sprite;
  7.     import flash.events.AsyncErrorEvent;
  8.     import flash.events.Event;
  9.     import flash.events.TimerEvent;
  10.     import flash.geom.Rectangle;
  11.     import flash.media.Video;
  12.     import flash.net.NetConnection;
  13.     import flash.net.NetStream;
  14.     import flash.utils.getTimer;
  15.     import flash.display.BlendMode;
  16.     import flash.utils.Timer;
  17.    
  18.     public class Main extends Sprite
  19.     {
  20.        
  21.         private var graphic1:Shape;
  22.         private var graphic2:Shape;
  23.         private var graphic3:Shape;
  24.         private var vect:Vector.<Vector.<Number>> ;     
  25.         private var bmd:BitmapData;
  26.         private var video_mc:MovieClip;
  27.        
  28.         private var rect:Rectangle;
  29.        
  30.        
  31.         public function Main():void
  32.         {
  33.             graphic1 = new Shape();
  34.             graphic2 = new Shape();
  35.             graphic3 = new Shape();
  36.            
  37.             stage.scaleMode = "noScale";
  38.             perspectiveDemo();
  39.  
  40.             bmd = new BitmapData(video_mc.width, video_mc.height);
  41.            
  42.             addChild(graphic1);
  43.             addChild(graphic2);
  44.             addChild(graphic3);
  45.            
  46.             graphic1.blendMode = BlendMode.SCREEN;
  47.             graphic1.x = 30;
  48.             graphic1.y = 200;
  49.             //graphic1.scaleY = .15;       
  50.            
  51.             graphic2.blendMode =BlendMode.SCREEN;
  52.             graphic2.x = 30;
  53.             graphic2.y = 200;
  54.             //graphic2.scaleY = .15;       
  55.            
  56.             graphic3.blendMode = BlendMode.SCREEN;
  57.             graphic3.x = 30;
  58.             graphic3.y = 200;
  59.             ///graphic3.scaleY = .15;
  60.            
  61.         }
  62.  
  63.        
  64.         private function perspectiveDemo():void
  65.         {
  66.            
  67.             video_mc = new MovieClip();
  68.             addChild(video_mc);
  69.             video_mc.x = 30;
  70.             video_mc.y = 30;
  71.            
  72.             var video:Video = new Video(320, 140);
  73.             var nc:NetConnection = new NetConnection();
  74.             nc.connect(null);
  75.             var ns:NetStream = new NetStream(nc);
  76.             ns.addEventListener(AsyncErrorEvent.ASYNC_ERROR, handleFakeError);
  77.            
  78.            
  79.             video_mc.addChild(video);
  80.             video_mc.x = 400;
  81.             video.attachNetStream(ns);
  82.             ns.play("http://gfxcomplex.com/labs/wall-e-tlr3_h320.mov");
  83.            
  84.             rect = new Rectangle(0, 0, 140, 300)
  85.            
  86.             var timer:Timer = new Timer(100);
  87.             timer.addEventListener(TimerEvent.TIMER, checkColor3);
  88.             timer.start();
  89.    
  90.         }
  91.        
  92.         private function handleFakeError(e:AsyncErrorEvent):void
  93.         {
  94.                 //
  95.         }
  96.        
  97.        
  98.         private function checkColor3(e:TimerEvent):void {
  99.  
  100.             bmd.draw(video_mc);
  101.            
  102.             vect = bmd.histogram(rect);
  103.            
  104.            
  105.             for (var i:int = 0; i <256; i++)
  106.             {         
  107.                
  108.                
  109.                 graphic1.graphics.lineStyle(.25, 0xff0000);
  110.                 graphic1.graphics.moveTo(i, 0);
  111.                 graphic1.graphics.lineTo(i, -(vect[0][i]));
  112.                
  113.                 graphic2.graphics.lineStyle(.25, 0x00ff00);
  114.                 graphic2.graphics.moveTo(i, 0);
  115.                 graphic2.graphics.lineTo(i, -(vect[1][i]));
  116.                
  117.                 graphic3.graphics.lineStyle(.25, 0x0000ff);
  118.                 graphic3.graphics.moveTo(i, 0);
  119.                 graphic3.graphics.lineTo(i, -(vect[2][i]));
  120.  
  121.             }
  122.             graphic1.graphics.clear();
  123.             graphic1.graphics.clear();
  124.             graphic1.graphics.clear();
  125.         }
  126.     }
  127. }

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2 comments so far

Add Your Comment
  1. Pixelero said: 2008.09.21 11:58

    That sounds really slow. I did some speed testing, and it seems to work just fine - at least with bitmapdata of a still-photo , yet I don't know how video would affect that ...

  2. Josh Chernoff said: 2008.09.21 15:08

    How did my code look to you? Maybe I have some bad coding?

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