DiffPDF===========DiffPDF is used to compare two PDF files.By default the comparison is of the words on each pair of pages, butcomparing character by character is also supported (e.g., forlogographic languages). And there's also support for comparing the pagesby appearance (for example, if a diagram is changed or if a paragraph isreformatted, or a font changed). It is also possible to compareparticular pages or page ranges. For example, if there are two versionsof a PDF file, one with pages 1-12 and the other with pages 1-13 becauseof an extra page having been added as page 4, they can be compared byspecifying two page ranges, 1-12 for the first and 1-3, 5-13 for thesecond. This will make DiffPDF compare pages in the pairs (1, 1), (2,2), (3, 3), (4, 5), (5, 6), and so on, to (12, 13).A couple of example PDF files are provided online so that you can try itout. PDF files can be loaded from the GUI (by pressing the File #1 andFile #2 buttons), or by specifying them on the command line. Moreinformation is available in the program's tooltips and About box.(If you want a command line tool for comparing PDFs seehttp://www.qtrac.eu/comparepdf.html.)Home page:http://www.qtrac.eu/diffpdf.htmlWindows Users=============Download the zip file, e.g., diffpdf-1.9.2.zip (where the number willvary depending on the version). Navigate to the file in Windows Explorerand use the context menu to choose the Extract All option. It doesn'tmatter what folder you extract to, but best to use one specifically forDiffPDF. The folder will contain diffpdf.exe and may contain some .dllfiles too. If there are .dll files, you must not move diffpdf.exe to anyother folder!Once unzipped you can double-click diffpdf.exe to run it. You might alsolike to add a shortcut to it from the desktop or from the start menu.Compiling and Installing DiffPDF (Mac-specific notes are at the end.)================================Prerequisites: A C++ compiler, the Qt 4 libraries (I test with Qt 4.7and Qt 4.8. Earlier Qt's may work although Qt 4.4 and 4.5 will at leastneed a compiler with tr1 support), and the Poppler libraries (at least0.20.1, including Poppler's Qt 4 headers). Linux and BSD users should beable to get everything through their package management system---andsome distros already include diffpdf so you don't even have to build it.Mac OS X users can get a compiler by installing Xcode; you'll need toget Qt and Poppler separately.1. Unpack the archive file, diffpdf-XXX.tar.gz    $ tar xvfz diffpdf-XXX.tar.gz2. Change directory to diffpdf-XXX    $ cd diffpdf-XXX3. Run lrelease; on some sytems this might be called lrelease-qt4    $ lrelease diffpdf.pro4. Run qmake; on some systems, run qmake-qt4    $ qmake5. Run make    $ make6. Copy or soft-link the diffpdf executable to somewhere on your PATH7. Only the executable is needed; all the files that were unpacked or   generated can be safely deleted.That's it!Running DiffPDF===============A pair of tiny example files are available:http://www.qtrac.eu/boson1.pdf andhttp://www.qtrac.eu/boson2.pdf. Youcan use these to see the difference between text and appearancecomparisons and to get a feel for how DiffPDF works.If you hit a bug, please report it to mark@qtrac.eu. Be sure to include"DiffPDF" in the subject line and specify the version you are usingand details of your system, e.g., operating system name and version,compiler name and version, Qt library version, Poppler library version.License=======This program was written by Mark Summerfield.Copyright © 2008-13 Qtrac Ltd. All rights reserved.This program is free software: you can redistribute it and/or modify itunder the terms of the GNU General Public License as published by theFree Software Foundation, either version 2 of the License, or (at youroption), any later version. This program is distributed in the hope thatit will be useful, but WITHOUT ANY WARRANTY; without even the impliedwarranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See theGNU General Public License (in file gpl-2.0.txt) for more details.Building on Mac OS X====================Here's how to build it:$ /usr/bin/ruby -e "$(curl -fsSLhttps://raw.github.com/gist/323731)"$ brew install qt$ brew install poppler --with-qt4# Dirs must be writeable because macdeployqt modifies copied files$ chmod -R u+w /usr/local/Cellar/qt/$ chmod -R u+w /usr/local/Cellar/poppler/$ curl -Ohttp://www.qtrac.eu/diffpdf-1.5.0.tar.gz$ tar xvfz diffpdf-1.5.0.tar.gz$ cd diffpdf-1.5.0$ lrelease diffpdf.pro$ qmake -spec macx-g++$ makeHere's how to make a .dmg:# Fix references, remove unneeded Frameworks and build DMG$ macdeployqt diffpdf.app/$ cd diffpdf.app/Contents/Frameworks/$ rm -r QtDeclarative.framework/ QtNetwork.framework/QtScript.framework/ QtSql.framework/ QtSvg.framework/QtXmlPatterns.framework/$ cd ../../..$ hdiutil create diffpdf-1.5.0.dmg -srcfolder diffpdf.app/Thanks to Dirk Loss for this information.