var byteArray = bitmapData.getPixels(new Rectangle(0,0,sprite.width,sprite.height));

        #if flash
        var bytes = Bytes.ofData( byteArray);

        #else
        var output = new haxe.io.BytesOutput();
        for(i in 0...byteArray.length)
            output.writeByte(byteArray[i]);
        var bytes = output.getBytes();

        #end