Converting PDFs to the Amazon Kindle is not a straightforward affair. While there are many tools that can do the conversion to another format such as .MOBI, re-casting a typical PDF document into an ebook that works on a small screen requires more than mere change of format.
Formatting a PDF for the kindle can be done in two ways; the first is to CROP a PDF ebook then change it into a Kindle friendly file format. This allows for continuous text, uninterrupted with headers, footers, and page numbers, that is very much Kindle-friendly. You can read a detailed tutorial about this by following this link (henceforth referred to as ‘my first post’).
The second way is to essentially do the same thing as described above, but in an automated way that takes all the manual intervention and decisions out of it, using a free program called K2PDFOpt. This software works by converting your PDF to bitmap images, identifying the viewable areas, then assembling these into smaller pages without excess margins. Not only does this automate the work, but is ideal for multiple column documents. It has both advantages and disadvantages as detailed below.
How to convert with K2PDFOpt
1. Download K2PDFOpt (free software available for Windows, Linux, and MacOSX).
2. Grab the PDF document (or multiple documents, or a folder full of PDFs) and drag them to the K2PDFOpt icon. K2PDFOpt will start processing and you will see a screen similar to the screenshot on the right;
3. Once finished, new PDF files will be created in the same location as the originals with _k2opt at the end of the name of each.
The kind of results to expect:
1. File size: each resulting PDF will be much larger in size than the original (a 2 meg PDF was transformed into a 58 meg file).
This is because K2PDFOpt actually transforms the ebook into image bitmaps first before repackaging it as a PDF.
2. What the PDF will look like: see below for some examples
After processing (showing 2 pages)
See also results for 2column (from the program web site)
After processing (showing 2 pages)
However, there were instances where the pages had random text artifacts that were incorrectly sized (see screenshot below)
The text in large font on this page in fact was not supposed to be sized differently from the rest of the text.
PROS: the advantages of using K2PDFOpt (vs. doing it manually as per my first posting)
1. Fully automated. No work on your part is necessary, no decisions to be made
2. Can process books in batch: which is helpful if you have a folder choc full of PDF ebooks that you want to process en masse. Note, though, that this can take a very long time, so you might want to do it overnight or something like that. Also watch out for file sizes, which can get out of hand (see below).
3. Works very well: generally speaking
4. Works well for documents containing columns: which are even more labor intensive if cropped/process as per the first post.
CONS: the disadvantages of using K2PDFOpt (vs. doing it manually as per my first posting)
1. You can potentially get better looking documents: if you you crop manually then convert. In some cases, cropping alone can produce a Kindle friendly PDF.
2. File sizes: are very large when processed with K2PDFOpt. If you have, say 500 megs of PDF ebooks, you’re looking at something like 15 gigs of PDF files when K2PDFOpt has processed it. In contrast, file sizes will not increase with the cropping/conversion operation described in the first post. (You also have to think about the hard drive size of your Kindle if you’re going to be adding many big files to it).
3. Headers/footers still find their way into the document: which is to say, you don’t really get an uninterrupted text flow, as you would from a native MOBI ebook for example.
4. Converting text to images reduces functionality: for example it makes the document unsearchable, un-highlightable; words cannot be translated, etc.
The verdict: K2PDFOpt is a brilliant and remarkably effective tool. I am amazed just thinking about the planning that had to have gone into figuring out the logic and execution of this beautiful piece of software.
Having said that, I still think there is a place for cropping and converting PDFs manually as described in my first post, just because there is at least the possibility of an even better outcome.
But in terms of convenience and ease of use, K2PDFOpt is king. It is the closest to a 1-click solution for PDF to Kindle conversion that you can get.
[Thanks go to reader Willus for tipping me off about K2PDFOpt in the comments section of my first post on this subject]