ActionScript 3.0 :: Converting Image Into A Readable ByteArray?

I'm trying to read out some BitMapData into some kind of readable output.

Reason for this is I'd like to trace out the ByteArray and hopefully cut and paste its details into an .as file and then compare it against another BitMapData Object or byteArray that is generated within the app.

Basically I want to compare differences between the two and report back how many pixels or something are different.

It might seem like a strange or approach.

I can create a BitMapData Object, it traces back as [object BitMapData] - so I thought awesome just loop through the Object... But looping through the Object traces nothing at all back out.

So I tried to create a ByteArray and then convert that to a string, but all I get is wierd 'y' chars with two dots on the top of the char.

I've left some code below,

Code:
public function GetAndCompareBitmapData(target:DisplayObject) {
var bd:BitmapData=new BitmapData(target.width,target.height);
trace("bitmapData "+ bd); // trace [object BitMapData]

[Code].....