private void InitializeImageFrame(int frame)
{
imageTransform = CGAffineTransform.MakeIdentity();
SetImageInformation (frame);
var cg = CGImageSource.FromDataProvider(dataProvider).CreateImage(frame, null);
imageTransform = new CGAffineTransform(1, 0, 0, -1, 0, cg.Height);
//InitWithCGImage (cg);
NativeCGImage = cg;
GuessPixelFormat ();
}