image extraction questions

 

qp->LoadFromFile($path_to_pdf.'test.pdf');

$imagecount = $qp->FindImages();

if ($imagecount>0) {
 for ($image = 1; $image <= $imagecount; $image++) {
  $imageid = $qp->GetImageID($image);
  $qp->SelectImage($imageid);
  switch ($qp->ImageType()) {
   case 1: $imagetype = "jpg"; break;
   case 2: $imagetype = "bmp"; break;
   case 3: $imagetype = "tif"; break;
  }
  $qp->SaveImageToFile($path_to_pdf."image".$image.".".$imagetype);
 }
}

 

I tried this with a PDF with 2 pages, and 7 Pictures (all .bmp)

 

The Problem is, that the saved Images are partly incorrect in the Colors. All 7 images are drawings on white Background. But 4 of the saved images has reversed Colors :/ So The Background is Black and the Lines are white. So of course I can use a image library to revert the Colours of the Image, but how is it possible to find out which images have correct Colours and which does not? Of course I want save all Images of the PDF in the correct Colour ;)

 

I tried a small shell program (pdfimages.exe) to extract the Images from the same pdf. With this program, all Images have the correct Colour, so it had to be possible to get the correct Colours width QuickPDF, too?

 

And another question: On the first page of the PDF are 5 pictures, on the second page are 3 pictures. How can I extract the Page Number of the Images, or Extract only the Images of the Current Page? I need the assignment between pages and images.