It is possible, but hardly feasible.
You can open PDF documents in PHP using FPDI . It generates an abstract tree of PDF objects in memory. TCPDF and FPDF can save it back.
However, crossing the specified tree and finding the right attributes is very. (I happen to be a verb.)
Now the PDF format is actually available to humans. And this will undoubtedly contain the coordinates in a readable format (mainly in IIRC clauses). Therefore, you can detect this with a simple regular expression if you only knew where to look. Some sites just have to be gzuncompress () ed, and you are not trying to modify the document or save it anyway. So try FPDI and print_r () to develop a strategy.
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