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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 can chip be made from sand
Eke Reply
is this allso about nanoscale material
are nano particles real
Missy Reply
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
where is the latest information on a no technology how can I find it
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
has a lot of application modern world
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
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
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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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