Determine if a PDF file contains only images

One way would be to look for fonts.  Use the the "HasFontResources" function.  If the return equals false then it probably is a rasterized PDF.

 

For the reverse (text only PDF), you can use the "FindImages" method. 

 

Tom

 

You can use the textextraction from each page.

If there's no result then there are only images.

 

Another thing to determine if there are scanned

pages without ocr-run: Check if there are as many

imageobjects as there are pages.

 

Cheers, Ingo

 

To make sure that there are no visual elements on the page beside images we just need to remove all images from the page.

After this page should become visually empty (blank).

Here is PageContainsImages() function that basically answers are there any images on PDF page.

Your opinion and testing results are welcome.

 

procedure ClonePageDimensions(QPL: TQuickPDF;
    SourcePage, TargetPage: Integer);
  type
    TPageBox = record
      Left: Double;
      Top: Double;
      Width: Double;
      Height: Double;
    end;
  var
    i: Integer;
    width, height: Double;
    rotation: Integer;
    boxes: array [1..5] of TPageBox;
  begin
    with QPL do
    begin
      // Reading dimensions from Source Page
      SelectPage(SourcePage);
      width := PageWidth;
      height := PageHeight;
      rotation := PageRotation;
      for i := 1 to 5 do
      begin
        boxes.Left := GetPageBox(i, 0);
        boxes.Top := GetPageBox(i, 1);
        boxes.Width := GetPageBox(i, 2);
        boxes.Height := GetPageBox(i, 3);
      end;
      // Saving dimensions to Target Page
      SelectPage(TargetPage);
      SetPageDimensions(width, height);
      RotatePage(rotation);
      for i := 1 to 5 do
        SetPageBox(i, boxes.Left, boxes.Top, boxes.Width, boxes.Height);
    end;
  end;

 

  function PageContainsImages(QPL: TQuickPDF;
    Page: Integer; DPI: Integer): Boolean;
  var
    i: Integer;
    doc, doc_tmp: Integer;
    s, s_tmp: AnsiString;
  begin
    Result := False;
    with QPL do
    begin
      try
        // custom Document is selected
        if FindImages = 0 then
          Exit;
        doc := SelectedDocument;
        doc_tmp := NewDocument;
        // temporary Document is selected
        CopyPageRanges(doc, IntToStr(Page));
        // Page 2 contains customer's page copy atm
        SelectPage(2);
        // clear all image content on Page 2
        for i := 1 to FindImages do
          ClearImage(GetImageID(i));
        // Page 1 is empty and its dimensions should be equal to Page 2
        ClonePageDimensions(QPL, 2, 1);
        s := RenderPageToString(DPI, 2, 0);
        s_tmp := RenderPageToString(DPI, 1, 0);
        // Compare Page 1 and Page 2 by size and content
        if Length(s) <> Length(s_tmp) then
          Exit;
        Result := True;
        for i := 1 to Length(s) do
        if s <> s_tmp then
        begin
          Result := False;
          Exit;
        end;
      finally
        RemoveDocument(doc_tmp);
      end;
    end;
  end;