PDF to text conversion

There is once in a while the need to extract pure text from PDF files. This blog shows some attempts to do it with dot, with ruby, and with command line utitilites.

Dotnet

SautinSoft

See SautinSoft.

#r "nuget: sautinsoft.pdffocus"

let fn = "filename"
let focus = new SautinSoft.PdfFocus();
focus.OpenPdf(fn)
printfn "page count = %i" focus.PageCount
let result = focus.ToText()
printfn "result: %s" result

Unfortunately, the result was always empty.

iText7

See itext7-dotnet.

See dotnet-queries.

#r "nuget: itext7"

open iText.Kernel
open iText.Kernel.Pdf

let reader = new PdfReader(fn)
let doc = new PdfDocument(reader)
let pages = [ for pn in 1 .. doc.GetNumberOfPages() do yield doc.GetPage(pn) ]

pages 
|> Seq.map (fun page -> Canvas.Parser.PdfTextExtractor.GetTextFromPage(page))
|> String.concat Environment.NewLine

This works nicely and extracts the text from the PDF file. Note that this was not tried on PDF files which were scanned.

Ruby

With ruby, I found some quite useful libraries (ruby calls them gems) to do this.

pdf-reader will read a pdf file (not a scanned one) and transfer it per page into text. To use it, you first have to install the gem:

$ gem install pdf-reader

Then use it in your ruby code:

require 'pdf-reader'

reader = PDF::Reader.new("myfile.pdf")
text = reader.pages.map do |page|
    page.text
end

The docmentation of pdf-reader is quite good, it worked successfully for me to analyse several thousand pdf files.

Command line utilities

I found two command lines utilities, xpdf andn poppler which does a lot of pdf conversions.

### xpdf

It can be installed using:

brew install xpdf

Another option according to above is poppler:

brew install poppler

Poppler is a library, not a command line utility.

I haven’t tried either so far.

Other utilities

xpdf installs the following command line tools:

xpdf: PDF viewer (click for a screenshot)
pdftotext: converts PDF to text
pdftops: converts PDF to PostScript
pdftoppm: converts PDF pages to netpbm (PPM/PGM/PBM) image files
pdftopng: converts PDF pages to PNG image files
pdftohtml: converts PDF to HTML
pdfinfo: extracts PDF metadata
pdfimages: extracts raw images from PDF files
pdffonts: lists fonts used in PDF files
pdfdetach: extracts attached files from PDF files

% pdftotext -h
pdftotext version 4.05 [www.xpdfreader.com]
Copyright 1996-2024 Glyph & Cog, LLC
Usage: pdftotext [options] <PDF-file> [<text-file>]
  -f <int>               : first page to convert
  -l <int>               : last page to convert
  -layout                : maintain original physical layout
  -simple                : simple one-column page layout
  -simple2               : simple one-column page layout, version 2
  -table                 : similar to -layout, but optimized for tables
  -lineprinter           : use strict fixed-pitch/height layout
  -raw                   : keep strings in content stream order
  -fixed <number>        : assume fixed-pitch (or tabular) text
  -linespacing <number>  : fixed line spacing for LinePrinter mode
  -clip                  : separate clipped text
  -nodiag                : discard diagonal text
  -enc <string>          : output text encoding name
  -eol <string>          : output end-of-line convention (unix, dos, or mac)
  -nopgbrk               : don't insert a page break at the end of each page
  -bom                   : insert a Unicode BOM at the start of the text file
  -marginl <number>      : left page margin
  -marginr <number>      : right page margin
  -margint <number>      : top page margin
  -marginb <number>      : bottom page margin
  -opw <string>          : owner password (for encrypted files)
  -upw <string>          : user password (for encrypted files)
  -verbose               : print per-page status information
  -q                     : don't print any messages or errors
  -cfg <string>          : configuration file to use in place of .xpdfrc
  -listencodings         : list all available output text encodings
  -v                     : print copyright and version info
  -h                     : print usage information
  -help                  : print usage information
  --help                 : print usage information
  -?                     : print usage information

Dotnet#

SautinSoft#

iText7#

Ruby#

Command line utilities#

Other utilities#