SubImage VS PrinterImage
Those two functions of DicomImage sometimes get people confused as which should they use and which not. A few points here to clarify so after reading this you should be able to tell the difference. Neither method changes anything in the original image - they both return modified copies.
SubImage Returns an Identical copy of the original, apart from the left, top, width and height. The returned new DicomImage could be just an area of the original image or of the same size.