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krop: A tool to crop PDF files

What is krop?

krop is a simple graphical tool to crop the pages of PDF files.

  • The functionality of krop is perhaps best indicated by some screenshots.
  • krop should work on any recent Linux distribution, see how to install krop. I don't know if krop can be used on Windows or Mac after a sufficient amount of tinkering: please let me know in case you succeed.
  • It is written in Python and relies on PyQT, python-poppler-qt4 and pyPdf or PyPDF2 for its functionality.
  • It is free software, released under GPLv3+ in the sole hope that you or someone else may find it useful.
  • A unique feature of krop, at least to my knowledge, is its ability to automatically split pages into subpages to fit the limited screensize of devices such as eReaders. This is particularly useful, if your eReader does not support convenient scrolling. (In fact, I wrote krop to be able to read mathematical papers on my Nook.)
  • Possible alternatives to krop include PDF-Shuffler and briss.
  • Please report bugs to mail@arminstraub.com. Patches with improvements would, of course, be wonderful.

What krop fails to do

Unfortunately, there is no simple way to eliminate unnecessary/invisible parts of a pdf. krop only adjusts which parts of a PDF are displayed; the original content is still there in the file and will, for instance, show up when editing the file in inkscape. As a result, krop is not suited for the following:

  • censor a PDF document
  • decrease the size of a PDF file

Adobe Acrobat is able to do these things, but I am not aware of any free library with that ability. However, if you are willing to rasterize a PDF (that is, treat its content as a fixed size image), you can use free software like ghostscript to censor PDF documents.

Please let me know if you know of an open library that can delete invisible parts of a pdf.

Changelog

 krop 0.4.13 2017/07/22Armin Straub
+Added the command line option --go, which outputs a PDF using the choices from --autotrim, --rotate and --whichpages, without opening the krop GUI (thanks to Mirko Weihrauch for the idea).
+Padding for auto trimming can be specified as in CSS using one to four values. This option is now also available on the command line as --autotrim-padding. (Thanks to Jonah Langlieb for providing sanity checks!)
*Fix incorrect string handling when opening files from the command line using python3 (thanks to Giuliano Costantini for observing and fixing this).
 
 krop 0.4.12 2017/01/22Armin Straub
*Use CropBox instead of MediaBox when determining the region to be cropped (thanks to Tim Mueller for observing and fixing this).
*Use a more proper Python package structure (thanks to Xavier Corredor Llano for advice).
 
 krop 0.4.11 2016/08/20Armin Straub
*Make krop compatible with both python2 and python3.
 
More ...

Download krop

Please read below how to install krop, if you are unsure which file to download.

LinkSizeDescriptionHits
35.79 KB krop 0.4.13 (source code) 375
800 Bytes krop 0.4.13 (ebuild) 55
18.46 KB krop 0.4.13 (Debian package) 370
34.78 KB krop 0.4.12 (source code) 940
800 Bytes krop 0.4.12 (ebuild) 211
17.72 KB krop 0.4.12 (Debian package) 1097
More Downloads... 

Give krop a try without installing

Download the source package, say krop-0.4.13.tar.gz, and start krop directly:

$ tar xzf krop-0.4.13.tar.gz
$ cd krop-0.4.13
$ python -m krop

This should work using either version 2 or 3 of Python.

This will only work if PyQT, python-poppler-qt4 as well as pyPdf or PyPDF2 are already installed on your system (either via your distribution or installed manually).

Install krop

You should be able to install krop on any recent Linux distribution. The following distributions already include krop:

On the other hand, Debian packages are available for distributions based on Debian, which further includes kubuntu, Ubuntu and Linux Mint. Finally, you can install krop from sources on any distribution such as Arch.

After installing krop by one of these methods, it should be available on the command line as krop and you can call it without parameters or with one parameter specifying the PDF file you would like to open. If you install krop using the Debian package (which is recommended as it allows for easy uninstalling), it should also become available in the desktop menu as well as in the context menu of PDF files.

Install from Debian package

The following instructions have been tested using a standard installation of kubuntu, version 12.10 or higher, as well as Linux Mint, version 15 KDE. Little adjustment should be needed for other Debian-based distributions.

For this approach you need to download only a Debian package, say, krop_0.4.13-1_all.deb.

If gdebi is installed (its command line version resides in the package gdebi-core), then

$ sudo gdebi krop_0.4.13-1_all.deb
should be sufficient.

Otherwise, we install the dependencies by hand, that is:

$ sudo apt-get install python-poppler-qt4 python-pypdf2
$ sudo dpkg -i krop_0.4.13-1_all.deb
If using python3, you would use sudo apt-get install python3-poppler-qt4 python3-pypdf2 instead. (On older systems, we would install python-pypdf instead.)

Install from source package

First, you need to install PyQT, python-poppler-qt4 as well as pyPdf or PyPDF2, so that they are each available from within python.

It should then be sufficient to download the source package, say krop-0.4.13.tar.gz, and issue something along the lines of:

$ tar xzf krop-0.4.13.tar.gz
$ cd krop-0.4.13
$ sudo python setup.py install

If you wish to install krop into the desktop menu, you can either do this by hand or use the included krop.desktop file:

$ xdg-desktop-menu install --novendor krop.desktop
It may take a while for the menu entry to appear.

For options to uninstall krop, see http://stackoverflow.com.

A few tricks

  • If you press Trim Margins on a page without selections, then krop will automatically create a region for the full page with the margins trimmed.
  • If you are cropping a PDF file with many pages, then you may have some exceptional pages which need to be cropped in a different way then the other pages. In that case, the option Exceptions under Selections apply to will be useful to you.
  • You can use krop --go on the command line (without the GUI) to automatically
    • extract certain pages,
    • rotate pages, or
    • trim empty margins (the margins are determined from the --initialpage).
    For instance:
    $ krop --go --rotate 90 --autotrim -o ~/output.pdf input.pdf
    
    To get around the error "cannot connect to X server", you can prefix this command with xvfb-run (in the package xvfb on Debian and Ubuntu).
  • Run krop with --help to get a list of all possible arguments (for instance, --initialpage 5 starts krop with the fifth page open).
  • To add the dimensions of your own eReader to the 'Fit screen of device' choices, you can edit the configuration file. The location of this file may differ from system to system, but a good place to start looking is ~/.config/arminstraub.com/krop.conf. Don't forget to adjust the counter size= after adding your entries in the devicetypes section.
  • If you run into the error "multiple definitions in dictionary" while cropping a file, then this is because pyPdf is too strict. You can either upgrade to PyPDF2 or proceed as indicated in this bug report.

Some TODOs

 Missing
+Specify aspect ratio of crop regions
+Clone regions (and keep them linked)
+Make it possible to save and later reuse regions.
+Support PyPDF2 besides pyPDF
+Preserve meta data, table of contents and bookmarks when cropping
+Allow translations
+Is there a clean solution to shut down on CTRL+c? (see http://stackoverflow.com/questions/4938723/)
+Shortcuts
 
 Ideas
+Option to overlay pages in order to improve making selections
+Better support for handling a large number of files
+Automatize splitting pages in common ways (for instance, one page into two equally sized pages).