It is actually very easy. From this I learn that you don't really know copyPixels, which is a shame, you should learn and use that
Originally Posted by bluemagica
import flash.display.BitmapData; // we will be using bitmapdatas
import flash.geom.Point; // we'll need points
import flash.geom.Rectangle; // we'll need rectangles.
var picture:BitmapData = BitmapData.loadBitmap("picture"); // just loading the picture, there are actually several ways of doing this.
var newPicture = new BitmapData(32, 32, true, 0xff0000ff); // creating the new picture for your 32 x 32 corner.
var mc:MovieClip = _root.createEmptyMovieClip("jklsadf", _root.getNextHighestDepth()); // creating a movieclip that will show the bitmapdatas.
newPicture.copyPixels(picture, new Rectangle(0, 0, 32, 32), new Point(0, 0)); // cutting out the corner
mc.attachBitmap(newPicture, _root.mc.getNextHighestDepth()); // attaching the picture to the mc so it will show.