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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

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
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what does nano mean?
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nano basically means 10^(-9). nanometer is a unit to measure length.
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Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
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it is a goid question and i want to know the answer as well
characteristics of micro business
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s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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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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