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Store the modified pixel data in the bitmap

Listing 6 copies the modified pixel data from the ByteArray object back into the bitmap, overwriting the pixel data previously stored in the bitmap.

Store the modified pixel data in the bitmap.

//Put the modified pixels back into the bitmapData // object.rawBytes.position = 0;//this is critical bitmapData.setPixels(new Rectangle(0,0,bitmapData.width,bitmapData.height), rawBytes);} //end processChromaKey method//--------------------------------------------------//} //end class } //end package

I explained all of the code in Listing 6 in the earlier lesson titled Fundamentals of Image Pixel Processing.

The end of the class

Listing 6 also signals the end of the method, the end of the class, the end of the package, and the end of the program.

Run the program

I encourage you to run this program from the web. Then copy the code from Listing 7 and Listing 8. Use that code to create a newproject. Compile and run the project. Experiment with the code, making changes, and observing the results of your changes. Make certain that you can explain whyyour changes behave as they do.


I will publish a list containing links to ActionScript resources as a separate document. Search for ActionScript Resources in theConnexions search box.

Complete program listings

Complete listings for the program discussed in this lesson are provided in Listing 7 and Listing 8 below.


Listing of the class named driver.

/*Project ChromaKey01 This project scans all of the pixels in an image toidentify those pixels with a color of pure magenta. The alpha value for those pixels is set to zero to make themtransparent. *********************************************************/package CustomClasses{ import flash.display.Bitmap;import flash.display.BitmapData; import flash.geom.Rectangle;import flash.utils.ByteArray; import mx.containers.Canvas;import mx.controls.Image; import mx.events.FlexEvent;//====================================================//public class Driver extends Canvas { private var origImage:Image = new Image();public function Driver(){//constructor//Make this Canvas visible with a yellow background. setStyle("backgroundColor",0xFFFF00);setStyle("backgroundAlpha",1.0); //Load the origImage and embed it in the swf file.//Note the slash that is required by FlashDevelop. [Embed("/dancer.png")]var img:Class; origImage.load(img);//Register a CREATION_COMPLETE listener this.addEventListener(FlexEvent.CREATION_COMPLETE,completeHandler); } //end constructor//--------------------------------------------------// //This handler method is executed when the Canvas has// been fully created. private function completeHandler(event:mx.events.FlexEvent):void{ //Get and save a reference to a Bitmap object// containing the contents of the origImage file. var origBitMap:Bitmap = Bitmap(origImage.content);//Set the width and height of the Canvas object// based on the size of the origBitMap bitmap. Make // ten pixels wider and twice as high as the// bitmap. this.width = origBitMap.width + 10;this.height = 2*origBitMap.height; //Add the original image to the Canvas object at// the default location of 0,0. this.addChild(origImage);//Clone the origBitMap to create a// duplicate. var dupBitMap:Bitmap = new Bitmap(origBitMap.bitmapData.clone());//Put the dupBitMap in a new Image object and // place it on the canvas below the original image.dupBitMap.x = 0; dupBitMap.y = origBitMap.height;var newImage:Image = new Image();newImage.addChild(dupBitMap); this.addChild(newImage);//Set the alpha value for all pixels in the new// image with a color of pure magenta to zero. processChromaKey(dupBitMap);} //end completeHandler //--------------------------------------------------////This method identifies all of the pixels in the// incoming bitmap with a pure magenta color and sets // the alpha bytes for those pixels to a value of// zero. private function processChromaKey(bitmap:Bitmap):void{//Get the BitmapData object. var bitmapData:BitmapData = bitmap.bitmapData;//Populate a one-dimensional byte array of pixel // data from the bitmapData object. Note that the// pixel data format is ARGB. var rawBytes:ByteArray = new ByteArray();rawBytes = bitmapData.getPixels(new Rectangle( 0,0,bitmapData.width,bitmapData.height));//Declare working variables. Note that there is// no requirement to deal with the green color // value in this case of testing for magenta.var cnt:uint; var red:uint;var green:uint; var blue:uint;for (cnt = 0; cnt<rawBytes.length; cnt += 4) { //alpha is in rawBytes[cnt]red = rawBytes[cnt + 1];green = rawBytes[cnt + 2];blue = rawBytes[cnt + 3];if ((red == 255)&&(green == 0 )&&(blue == 255)) {//The color is pure magenta. Set the value // of the alpha byte to zero.rawBytes[cnt] = 0;}//end if }//end for loop//Put the modified pixels back into the bitmapData// object. rawBytes.position = 0;//this is criticalbitmapData.setPixels(new Rectangle( 0,0,bitmapData.width,bitmapData.height),rawBytes);} //end processChromaKey method //--------------------------------------------------//} //end class } //end package

Listing of the mxml file.

<?xml version="1.0" encoding="utf-8"?><!-- Project ChromaKey01This project scans all of the pixels in an image to identify those pixels with a color of pure magenta. Thealpha value for those pixels is set to zero to make them transparent.--><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"xmlns:cc="CustomClasses.*"><cc:Driver/></mx:Application>


This section contains a variety of miscellaneous materials.

Housekeeping material
  • Module name: Using Chroma Key Compositing to Create Transparent Backgrounds
  • Files:
    • ActionScript0134\ActionScript0134.htm
    • ActionScript0134\Connexions\ActionScriptXhtml0134.htm
PDF disclaimer: Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.
Publication issues : This project was originally developed using the free open-source FlashDevelop development tool. However, because of limitations of the Connexions web site, it was necessary for me to convert the project to aFlex Builder 3 project to make it possible for you to run the program from this Connexions module.


Questions & Answers

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In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
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Source:  OpenStax, Object-oriented programming (oop) with actionscript. OpenStax CNX. Jun 04, 2010 Download for free at http://cnx.org/content/col11202/1.19
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