I have a web application where people can upload PDF files and I'm reviewing it online with Google Docs Viewer API, from a back-end web application. I can get many different PDF sources, because of that.
Some PDF are not correctly displayed: some text is missing. I can see the missing text when I open the PDF file with a "offline" PDF viewer, say Adobe Reader.
Any advice on this? how to understand/debug/modify the PDF on-the-fly to make it OK?
I found an example of an incorrect PDF, the "file" command says it's a 1.4 PDF version. Google Docs shows correctly some 1.7 files I have. I first thought it could be related to a very recent PDF version, but it seems not. (I read Which versions of the PDF standard does Google Docs support? before) So what?
I can provide someone with an incorrect file if needed.