9 Replies Latest reply on Aug 22, 2013 4:44 AM by Test Screen Name

    Paragraph detection in pdf


      Please, How can I detect paragrahs when reading pdf file?

        • 1. Re: Paragraph detection in pdf
          olafdruemmer Newcomer

          Hi Mohammed,


          PDF essentially does not have a concept of paragraphs - a page is just a 2 dimensional z-ordered arrangement of graphic objects -  with the following exception: if someone created the PDF such that it is adequately tagged using the standard structure types  (see chapter 14.8 of ISO 32000-1) then could detect paragraphs by looking for the P tags in the document (or heading, lists, table tags etc. accordingly).




          Am 22 Aug 2013 um 09:53 schrieb Mohammed_Mostafa <forums_noreply@adobe.com>:



          Paragraph detection in pdf

          created by Mohammed_Mostafa in PDF Language and Specifications - View the full discussion

          Please, How can I detect paragrahs when reading pdf file?


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          • 2. Re: Paragraph detection in pdf
            Mohammed_Mostafa Newcomer

            Many Thanks Mr Olaf for these information, so i must only deals with text cordinates!

            I would ask you another question how can handle this issue if i want to produce this text(paragrahs) in html file because coordinates only make the text interfere with each other??




            • 3. Re: Paragraph detection in pdf
              Test Screen Name Mythic

              Extracting text is DIFFICULT.


              You can use guesswork and fuzzy logic as all text extraction software must do.

              On no account place characters into the PDF separately using coordinates from PDF! This cannot work because the layout methods will be different.


              You can sort the information received by coordinate to put into a plausible reading order. You can then use fuzzy logic to guess where spaces might be, which are line breaks and which are paragraph breaks, whether there are columns, and anything else you want to guess and spend a lot of time programming, which the human eye does in half a second (a frustrating realisation).

              • 4. Re: Paragraph detection in pdf
                Mohammed_Mostafa Newcomer

                I know pdf has more difficults but at any case i will try and i must try.

                Many Thanks for you

                • 5. Re: Paragraph detection in pdf
                  Test Screen Name Mythic

                  Yes, it is important to know it is difficult, but that is not a reason not to do it.


                  One important point about the need for fuzzy logic which may be overlooked: it can mean that two valid programs for extracting PDF text can produce different results.


                  One more note: if a file is tagged, PDF text extraction can become accurate and precise: this is the reason for tagging. A quality PDF text extractor will handle this case too.

                  • 6. Re: Paragraph detection in pdf
                    Mohammed_Mostafa Newcomer

                    How can I detect that this pdf is tagged pdf?

                    • 7. Re: Paragraph detection in pdf
                      olafdruemmer Newcomer

                      You will have to read the PDF spec some more (chapter 14), and look at tagged PDF example files (makes it easier to udnerstand what chapter 14 is really about)!


                      Starting points:

                      • entry Marked in MarkInfo dict in Catalog set to true (please note that this key is in one case in chapter 14.7  in ISO 32000-1incorrectly stated as "Markings"  - this is a typo, and should say "MarkInfo" instead)
                      • StructTreeRoot key in Catalog is present and contains suitable data structures (the tagging information is contained under this root entry, and connected to page content through marked content in the contents streams, and sometimes OBJR references)



                      • 8. Re: Paragraph detection in pdf
                        swayam44 Newcomer

                        We propose and motivate a novel task: paragraph segmentation. We discuss and compare this task with text segmentation and discourse parsing. We present a system that performs the task with high accuracy. A variety of features is proposed and examined in detail. The best models turn out to include lexical, coherence, and structural features.

                        • 9. Re: Paragraph detection in pdf
                          Test Screen Name Mythic

                          Um, why have you posted the abstract of Dmitriy Genzel's paper? Without copyright acknowledgement?