While reading PDF files, I’m sure that you’ve come across those that have unnecessary white spaces between the beginning and the end of each individual page. One of the drawbacks of having these white spaces is that they force you to do unnecessary scrolling while reading.
So best solution is to crop it out and most of the time those spaces are equally spread out in each page. In those cases, a tool like “PDF-Quench” can come in real handy as it lets you easily crop pages.
You can define the cropping area using your mouse for a single page and simply hit the “save” button and it will crop all the pages (using the cropping value of that single page) and generate a new PDF file. If some pages are slightly longer, then make sure to adjust the margin accordingly (otherwise those pages will lose some of their content).

After creating a crop area, I usually navigate pages here & there just to make sure nothing won’t cropped out.
Main features …
*. It’s an extremely simple tool and has a clean UI.
*. Lets you zoom in/out the documents.
*. Navigate the PDF file (just like with a PDF viewer).
*. You cannot crop out each page individually.
*. Once done, simply hit the “save” button on the tool-bar and give your path for saving the file and you’re done!.
You can install PDF-Quench in Ubuntu 12.04 Precise Pangolin, 11.10 Oneiric Ocelot, 11.04 Natty Narwhal, 10.10 and 10.04 by first downloading the “.deb” file from this PDF-Quench download page.
Once the download complete, double click on the file and Ubuntu Software Center will install it for you. Or go to your downloaded directory and use the below command in your Terminal window should also work.
sudo dpkg -i pdf-quench_1.0.0_all.deb
Any limitations ??
Well, some PDF files have links that once clicked open other pages on it. But when you crop a PDF file’s content in ‘PDFQuench’, those links won’t work anymore. So please keep that in mind.
This has nothing to do with PDF-Quench as far as I know because once the actual size of the inner pages changes, the Index is not valid no more (as they depend on pixel/size values which define the navigation).
But for the record, you won’t lose any pages nor content and should still be able to navigate them using their page numbers & thumbnails nonetheless.

3 Comments
This came in handy as I am scanning my old magazines into PDFs. This will help take out some of the unneeded white space, therefore helping to reduce the size of the files. Great find!
You are welcome! :D.
For the same task I recently used PDF-Shuffler:
http://pdfshuffler.sourceforge.net/