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I have several class notes (more like books summarizing the material) that my college professors have provided in PDF form. As reading on a computer screen isn't exactly easy on the eyes (and gobbles unnecessary power compared to my Kindle) I'm looking for a way to convert these well. It would also be nice to be able to read/study in places where having a laptop would be impractical (e.g. weekend trips to places with no electricity provided, train travel).

I have already tried multiple file converters, including zamzar and Calibre, and the quality of both is no improvement on reading on a computer screen. I either receive gibberish (particularly when it comes to mathematical formulas) or else strange line breaks that make it difficult to follow the flow of the text, or both. This doesn't help the fact that I have to concentrate more anyways as the texts are not in my native language (I'm studying abroad in Germany). Reading pdfs on my Kindle is also not a viable option, as the constant moving back and forth over the page breaks my concentration as well.

I remember reading somewhere that converting to HTML, cleaning the code, and then converting to epub/mobi was suggested, but I can't find the article again and I wasn't sure what to do after converting the pdf to html (which seemed to work decently, and the HTML version looks good enough in my browser, besides small, rare garbled parts where certain mathematical symbols or special characters were, which I could live with and aren't of importance for non-math courses anyways). I would also be open to other roundabout ways of conversion (over an Open Office/Word text document, for instance) as long as the quality is good and easily readable.

As a student my budget doesn't really include commercial optical character recognition software. Can anyone help with this issue?

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    Why on earth would you need to convert something from PDF to mobi? With a Kindle Fire you can download a PDF app and read it directly. Any effort to convert it would be more trouble than it's worth. If you bought one of the larger size Kindles, the text should still be readable. This is one reason by the way that you should have a tablet which is 9 inches. With that size you can actually read PDFs off the screen quite neatly. The above solutions sound interesting, but you are overlooking the main problem -- that many documents are delivered in PDF form and that only a larger tablet is capable – idiotprogrammer Jul 31 '14 at 3:27
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    Get a used Kindle DX -- it has a native PDF reader, no conversion is necessary. – tcrosley Jul 31 '14 at 16:09
  • Could you use Evernote? Add the pdf to Evernote and see if looks ok there and then read it elsewhere? Should be a quick test. – wally thurston Sep 11 '14 at 4:04
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    @idiotprogrammer (Not intended as snark) If a computer screen is too much for their eyes, why would a tablet be better? It's still a back-lit screen and everything it's heir to (no matter what the size) - so how would that be better? – AnonJr Oct 16 '14 at 19:59
  • @AnonJr The described eye issues sound like something he could best resolve by just tweaking the brightness/contrast etc, but the core issue of reading pdf's on a more mobile device have really only 1 simple solution which is what idiotprogrammer was suggesting where using a tablet with pdf support is best since any other solution would require x amount more time spent converting each and every pdf to suitable reading material which approach would likely vary for each pdf. But I disagree that it has to be 9" as I have a Nexus 7 2013 which works fine. – Myzifer Apr 20 '15 at 15:51
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Simplest way is to send kindle team an email with the PDF attached along. They'll send you back the converted .mobi format.

Send to Kindle by E-mail Send documents to your Kindle as an email attachment You and your approved contacts can send documents to your registered Kindle devices, free Kindle reading applications, and your Kindle Library in the Amazon Cloud by e-mailing them to your Send-to-Kindle e-mail address ([name]@kindle.com). Your Send-to-Kindle e-mail address is a unique e-mail address assigned to each of your Kindle devices and free Kindle reading applications upon registration.

How to send a document to your Kindle: To find your Send-to-Kindle e-mail address, visit the Manage your Devices page at Manage Your Kindle. Documents can only be sent to your Kindle devices or apps from e-mail accounts that you added to your Approved Personal Document E-mail List. To add an e-mail account, visit the Personal Document Settings page at Manage Your Kindle. To send a document to your Kindle device or app, simply attach it to an e-mail addressed to your Send-to-Kindle e-mail. It is not necessary to include a subject in the email.

  • And the email address is? – Anthon Sep 2 '14 at 17:47
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    Just send it to your own kindle id with the subject as "convert" – user2598 Sep 2 '14 at 17:51
  • This is not recommended method. PDF can be nothing more like collection of images - and in most cases it is. As you can try this method in great number of situations mobi generated that way will be nothing more than bunch of images - no reflowable text. – Glorifind May 18 '15 at 13:22
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To get a good reflowable and readable text you would indeed, as you suggest, have to go to some OCR software. Tesseract is a free OCR software with good (IMHO) quality that you could use.

The problem is in the mathematical formula, I have not seen OCR software that does a good job in that area. That leaves two options:

  • Cut out the formula's as images and put them into the text at the places where the OCR faltered.
  • Rewrite the formula in some system that can generate HTML.

The second option is more work and more error prone. I have used that (in combination with the python sympy module and generating LaTeX), but of course any typo leads to incorrect formulae, something that is more difficult to achieve when just cutting out the formula as images.

One other, maybe less obvious, road is to ask the professor for the source material from which the PDF was generated. You might have an easier way starting from there. And your professor might be willing to supply you with the material with the lure of getting an ebook compatible version of the text in exchange. Even if the original material are individual scans, you are better of starting with those images for OCR, than with PDF files (which is, apart from its multipage capabilities, fundamentally unsuitable for scanned material)

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I have a solution that I think will work for you - very quick and easy - and involves NO CODING:

Amazon released an app called the Kindle Comic Creator: http://www.amazon.com/gp/feature.html?docId=1001103761

You can download it for free. It's still in beta, has a few bugs, wrt the TOC, and the documentation and support for it are pretty terrible but it does a few things very well, one of which is zoom-able panels.

Here's what I recommend, save your PDF into discrete JPEGS, you can do this through the file save menu and then load all those individual JPEGS into the comic creator, it has a guided set up process when you open the app and begin a new book, very simple, it will load all your JPEGS in chronological order. You can then run a detect all panels command and it basically will detect where items in the page are grouped together.

For each of these panels you will be able to zoom straight to that content, making for very easy reading. You can also edit the dimensions of the panels if the computer is detecting badly.

Once you have the panels where you want just export and compile to .mobi, it has a feature for this in the app of course. Keep in mind this will be a fixed format ebook still but with the zoom feature it should be much easier to read and can be easily exported to .mobi format and loaded on your kindle.

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I use an older Kindle (non-touch screen) and recently encountered the same problem with reading PDF files. Fortunately, I came across this awesome free web app:

http://www.pdf4kindle.com/

I've converted over ten PDF files to MOBI, and they all look great on my Kindle!

You can also convert PDF to EPUB for free:

http://www.pdfpocket.com/

protected by Community May 14 '15 at 19:51

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