If you have a mobile device with a small screen size, then while reading PDF files it might be necessary to crop out ‘unnecessary’ white space of the pages, as it can reduce the scrolling.
If you use Ubuntu, you can use a tool called ‘PDFQuench‘ for that. This tool however has a single drawback, and that is, it does not let you crop pages individually. Now this might not always be a necessity for a PDF that only contains texts as they usually come with equally sized pages.
However, the ones that contain images are usually not. And in that case, you can use another utility called ‘krop’ as it contains that and a few more additional (& useful) features.
‘krop’ lets you crop all the pages at once, even/odd pages or, crop individual pages with different crop-settings, exclude selected pages, add margins, rotate (individual or multiple pages) and comes with few built in ‘presets’ for eReaders (you can also add custom Width/Height settings).
It also comes with a toolbar that contains Open, ‘krop’ (Crop), Zoom in/out/Fit-screen and Next/Previous pages buttons as well. I tested it on Ubuntu 13.04 only, and it worked flawlessly. But according to the author (Dr. ‘Armin Straub’), the provided ‘deb’ package should also work on Kubuntu and Linux Mint.
You can change the Save location under the ‘Save to’ option. However, the button that brings up the ‘File Save’ dialog only shows itself when you hover over the end of the name field. It would be better if it is always visible though.
Update: This issue is now fixed with the recent 0.4.2x update (a thanks goes to Dr. ‘Armin Straub’ for letting me know that).
Anyway, ‘krop’ has a few python and Qt dependencies, but it did not take more than a couple of Kilobytes on my newly installed Ubuntu 13.04, so Gnome users can also enjoy using it without having to install a lot of dependencies.
If interested, then please download it from this page. Once the ‘deb’ file finishes downloading, simply double click on it and follow the instruction on ‘Ubuntu Software Center’ to install it.