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I'm looking for a fast and reliable way to read/parse large PDF files in Ruby (on Linux and OSX).

Until now I've found the rather old and simple PDF-toolkit (a pdftotext-wrapper) and PDF-reader, which was unable to read most of my files. Though the two libraries provide exactly the functionality I was looking for.

My question: Have I missed something? Is there a tool that is better suited (faster and more reliable) to solve my problem?

Javier
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6 Answers6

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You might find Docsplit useful:

Docsplit is a command-line utility and Ruby library for splitting apart documents into their component parts: searchable UTF-8 plain text, page images or thumbnails in any format, PDFs, single pages, and document metadata (title, author, number of pages...)

pw.
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    Javier: do take a look at Docsplit. It wraps the Apache PDFBox library for text extraction -- because we've had better quality results with PDFBox that pdftotext. – jashkenas Jun 15 '10 at 13:57
  • @pw. Installed all the libraries and followed all the documentation for this, however I was having a hard time, do you have any referrals for tutorials or documentation that goes beyond 2 lines of code? – Sean Larkin May 30 '13 at 19:08
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After trying different methods, I'm using PDF-Toolkit now. It's quite old, but it's fast, stable and reliable. Besides, it really doesn't need to be new, because it just wraps the xpdf commandline utilities.

Javier
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1

Did you have a look at the CombinePDF library?

It's a pure ruby solution that allows some PDF manipulation, such as extracting pages, overlaying one PDF page over another, page numbering, writing basic text and tables, etc'.

Here's an example for stumping an existing PDF file with a logo. The example reads a PDF file, extracts one page to use as a stamp and stamps another PDF file.

require 'combine_pdf'
company_logo = CombinePDF.load("company_logo.pdf").pages[0]
pdf = CombinePDF.load "content_file.pdf"
pdf.pages.each {|page| page << company_logo}
pdf.save "content_with_logo.pdf"

You can also stamp text, number pages or use :

require 'combine_pdf'

pdf = CombinePDF.load "content_file.pdf"

pdf.number_pages #adds page numbers. you can add formatting and placement options.

pdf.pages.each {|page| page.textbox "One Way To Stamp"}

#you can a shortcut method to stamp pages
pdf.stamp_pages "Another way to stamp"

#you can use the shortcut method for both text and PDF stamps
company_logo = CombinePDF.load("company_logo.pdf").pages[0]
pdf.stamp_pages company_logo

# you can use write simple tables
pdf.pages[0].write_table headers: ['first name', 'surname'], table_data: [['John', 'Doe'], ['Mr.', 'Smith']]

pdf.save "content_with_logo.pdf"

It's not meant for complex operations, but it complements most PDF authoring libraries and allows you to use PDF templates instead of writing the whole thing from scratch.

Myst
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1

You could use JRuby and a Java PDF library parser such as ApachePDFBox (https://www.ohloh.net/p/pdfbox). See also http://java-source.net/open-source/pdf-libraries.

insane.dreamer
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  • That sounds like an interesting alternative. Have you seen an implementation or an example somewhere? – Javier Apr 25 '09 at 00:15
  • @Trejkaz I guess I meant to say that I "only" wanted to read them and therefore wasn't planning to buy software for it? But who knows what I was thinking 6yrs ago? ;-) – Javier Apr 21 '15 at 09:14
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If you just need to get the text content out of a pdf file, pdftohtml at sourceforge is efficient. it is not suited for dealing with images.

Alexis Perrier
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Here's some options:

http://en.wikipedia.org/wiki/List_of_PDF_software

From that link, and searching sourceforge, there's a couple of command line utilities that might do what you want, like this one: http://pdftohtml.sourceforge.net/

Depending on your requirements and what the PDFs look like, you could look at using the Google Docs API (uploading the PDF and then downloading it as text), or could also try something like gocr. I've had a lot of luck parsing image text with gocr in the past, and you'd just have to bounce out to the shell to do it, like gocr -i whatever.pdf (I think it works with PDFs).

The downside to all of these is that they're not pure-Ruby implementations, but lots of the good (and free) OCR projects seem to be done that way.

Terry
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    Why would I need OCR ("optical character recognition") to read a PDF that doesn't consist of scanned text? Wouldn't that needlessly slow down the whole process? – Javier Apr 25 '09 at 00:14
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    No. OCR is the process of converting images to text. PDF readers and PDF toolkits utilize this concept to convert an image (the same that is output from, say, a scanner) to text. – Terry Apr 25 '09 at 04:00
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    So basically you're saying, that all text inside a PDF consists of an image that needs to be recognized as text first? – Javier Apr 25 '09 at 22:58
  • I'd be lying if I said yes or no. I just know I've had success with OCRs. – Terry Apr 26 '09 at 01:30
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    Some PDFs are scanned, others encode the text in ultra weird formats like (t)(h)(i)(s) (s)(o)(m)(e) (t)(e)((x)(t)) also some use deflate. – Cris Stringfellow Mar 01 '12 at 14:26