Towards High-Quality Text Stream Extraction from PDF. Technical Background to the ACL 2012 Contributed Task.

Extracting textual content and document structure from PDF presents a surprisingly (depressingly, to some, in fact) difficult challenge, owing to the purely display-oriented design of the PDF document standard. While a variety of lower-level PDF extraction toolkits exist, none fully support the recovery of original text (in reading order) and relevant structural elements, even for so-called borndigital PDFs, i.e. those prepared electronically using typesetting systems like LATEX, OpenOffice, and the like. This short paper summarizes a new tool for high-quality extraction of text and structure from PDFs, combining state-of-the-art PDF parsing, font interpretation, layout analysis, and TEI-compliant output of text and logical document markup.