Use this method to render the PDF to a
The output is a render of the current Doc.Rect of the current
Any page rotation specified in the PDF page is applied so that
the output render is the correct orientation. This may mean that
the output width and height are transposed copies of the width and
height as specified in the Doc.Rect.
You can then use this Bitmap for drawing to screen or for
manipulation using System.Drawing routines.