I would suggest creating a unique local connection name between your applications (swfs). Check out Joey’s blog on this task - unique local connection names. In this project summary, I will not reference a unique connection name.

Here is the set up… In the first swf, I’ve set up a LC object (transSendLC) and an image object (imgOriginal). The second app (swf) somewhat mimics the first app (swf). The only difference is that I created a custom class, inheriting from LC. I’ve added a method for receiving the ByteArray and a Bitmap object. The bitmap object can be used to bind to the Image source. Note: You don’t need to create a custom class. I found that it made sense for my particular flex project.

Within my first app (swf), I have supplied an image (imgOriginal). Now with I need to chop up the data and send it to the second app (swf).

Example Code:
...
var width:Number = imgOriginal.width
var height:Number = imgOriginal.height;
var bytes:ByteArray =
   imgOriginal.bitmapData.getPixels(new Rectangle(0, 0, width, height))

var tempByteArray:ByteArray;

// limit byteArray to 40K - localconnection limit
var byteLimit:uint = uint(40000);

if(bytes.length > byteLimit){

   var currentSize:uint = byteLimit;
   var position:uint = 0;
   var totalSize:uint = 0;

   while(totalSize < bytes.length){
      tempByteArray = new ByteArray();
      tempByteArray.length = currentSize;

      // Write bytes from position to current size
      tempByteArray.writeBytes(bytes, position, currentSize);

      //send ByteArray chunk
      transSendLC.send(uniqueLCName, "sendSnapShot",
              tempByteArray, bytes.length, width, height);

      //get current total and get next position
      totalSize = totalSize + tempByteArray.length;
      position = totalSize;

      //set current size based on limit
      currentSize = bytes.length - totalSize;
      if(currentSize >  byteLimit){
         currentSize = byteLimit;
      }
  }
  else{
     //less than limit - send Byte Array
     bytes.writeBytes(tempByteArray, 0, uint(bytes.length));
     imgLCSend.send(uniqueLCName, "sendByteArrayData",
                 tempByteArray, bytes.length, width, height);
  }
...

Next in my second app (swf), I need to build the sendCopy method within my custom object (inheriting from LC). Note: It is assumed that you have logic to connect the shared local connection name, a Bitmap and a ByteArray object in your custom class.

Example Code:
public function sendByteArrayData(bytes:Object, bytesLength:Number,
                              width:Number, height:Number):void {
   var byteArray:ByteArray = bytes as ByteArray;

   //New ByteArray size
   if(byteArraySnapShot == null){
      byteArraySnapShot = new ByteArray();
      byteArraySnapShot.length = bytesLength;
      byteArraySnapShot.position = 0;
   }

   //Write byte array
   byteArraySnapShot.writeBytes(byteArray);

   //Once length/size is filled based on total bytes create bitmap
   if(byteArraySnapShot.bytesAvailable == 0){
      var bitmapDataSnapShot:BitmapData = new BitmapData(width, height);
      byteArraySnapShot.position = 0;
      bitmapDataSnapShot.setPixels(new Rectangle(0, 0, width, height),
            byteArraySnapShot);

      var bitmapSnapShot:Bitmap = new Bitmap(bitmapDataSnapShot);
      snapShotImg = bitmapSnapShot;

      byteArraySnapShot = null;
   }

}

There perhaps a few ways to achieve the functionality. My purpose here is to show the process of reading and writing ByteArray in a real world application set.