Extracting text from PDFs in C#
Pretty simply, I need to rip text out of multiple PDFs (quite a lot actually) in order to analyse the contents before sticking it in an SQL database.
I've found some pretty sketchy free C# libraries that sort of work (the best one uses iTextSharp), but there are umpteen formatting errors and some characters are scrambled and alot of the time there are spaces (' ') EVERYWHERE - inside words, between every letter, huge blocks of them taking up several lines, it all seems a bit random.
Is there any easy way of doing this that I'm completely overlooking (quite likely!) or is it a bit of an arduous task that involves converting the extracted byte values into letters reliably?
Answer
There may be some difficulty in doing this reliably. The problem is that PDF is a presentation format which attaches importance to good typography. Suppose you just wanted to output a single word: Tap.
A PDF rendering engine might output this as 2 separate calls, as shown in this pseudo-code:
moveto (x1, y); output ("T")
moveto (x2, y); output ("ap")
This would be done because the default kerning (inter-letter spacing) between the letters T and a might not be acceptable to the rendering engine, or it might be adding or removing some micro space between characters to get a fully justified line. What this finally results in is that the actual text fragments found in PDF are very often not full words, but pieces of them.