Utility to re-structure research papers published in US Letter or A4 format PDF files potentially with 2 columns layout.
The goal is to try to make them more readable on ebook reader devices with small screen real-estate and without breaking the formating, fonts, math formulae, ...
It is reported to work quite well for 2 columns papers on the Amazon Kindle 3. Other ebook readers that natively support PDF rendering should benefit from this transformer as well.
Apache Software License 2.0 (as the main dependency: Apache PDFBox).
This project is alpha / experimental code. Features are implemented when needed. Expects bugs and not implemented exceptions.
Right now the program assumes an hardcoded 2 columns layout. It is planned to make it smarter by instrospecting the structure of the document to decompose parts in somewhat meaningful way.
Building from sources
You need a Java 6 SDK and Apache Maven, then:
$ mvn assembly:assembly
$ java -jar target/paper2ebook-VERSION.jar original.pdf [transformed.pdf]
If the output file is omitted, the file created is original_ebook.pdf.
How it works
To avoid breaking anything paper2ebook simply copy the original stream of PDF objects to the output PDF file but duplicates the number of pages so that each page in the ouput is a focus (using the CropBox property of PDF page objects) on a meaningful portion of the input page (e.g. the half left column, or a central figure, ...).
The current implementation does not try to remove duplicated objects hidden by the crop mask, hence the output PDF can be up to 4 times larger than the input file.
Heuristics to find the interesting portions to focus on is a work in progress.