PDF Image Extraction - How to extract image stamps?

Q: I am encountered a PDF which is a bit odd. Please find enclosed. It
has an image in the top left corner. When I process the file the image
is ignored. Can you shed some light on the issue?

I am using the standard element loop to discover objects in the
    while ((element = pageElementReader.Next()) != NULL)
        switch (element->GetType())

The image in the the top left corner is actually not part of the page
content but is an annotation drawn on top of the page. You can obtain
all anotations on a page using page.GetAnnot() method.

You can also use ElementReader to extract contents of annotation's
appearance stream. For example,

// If there are any annots on the page...
Annot annot = page.GetAnnot(0);
Obj* annot_appearance = annot.GetAppearance();
if (annot_appearance != NULL)
  while ((element = element_reader.Next()) != NULL) {
    switch (element->GetType()) {