Photos in PDF file not visible on iPad 2

A 6MB PDF file that contains photos works fine on my Mac. After I sync the file to my iPad 2 and open it in iBooks and GoodReader app, the text appears and layout remains unchanged but all photos are not visible.To fix the issue, just opening the original PDF file in Preview on your Mac and resaving to new file. Then taking it to the iPad and you are able to see all photos.