Calibre tidy line breaks

Globe Trotsky · 09-06-2025, 06:56 PM

I have an annoying problem that even after converting books in Calibre editor, some are riddled with random line breaks. Can someone advise me on how to fix without having to manually go through the HTML editor. Is there a code/regex/plug in. TIA. Apologies if this should be on another thread.

JSWolf · 09-06-2025, 08:41 PM

Quote:

Originally Posted by Globe Trotsky

I have an annoying problem that even after converting books in Calibre editor, some are riddled with random line breaks. Can someone advise me on how to fix without having to manually go through the HTML editor. Is there a code/regex/plug in. TIA. Apologies if this should be on another thread.

It looks like it could be a rather poor conversion from a PDF source.

You could use regex to combine lines that do not end in a punctuation mark. That would help a lot.

Read this thread, It gives a lot of good information including link(s) to regex to use. https://www.mobileread.com/forums/sh...d.php?t=357635

Sirtel · 09-06-2025, 08:53 PM

A crappy conversion from PDF will always be a crappy conversion, unless you fix everything by hand, line by line. PDF is not a suitable format for conversion.

TL;DR Don't convert from PDF if you can do it in any other way.

Globe Trotsky · Yesterday, 06:50 PM

Quote:

Originally Posted by JSWolf

It looks like it could be a rather poor conversion from a PDF source.

You could use regex to combine lines that do not end in a punctuation mark. That would help a lot.

Read this thread, It gives a lot of good information including link(s) to regex to use. https://www.mobileread.com/forums/sh...d.php?t=357635

Thanks I will have a read. I'm fairly certain this was an EPUB to start with. I just put it through Calibre Heuristics hoping that it would tidy everything up. Thanks for the link

Globe Trotsky · Yesterday, 06:52 PM

Thanks, as I said above, just checked and it was an EPUB, definitely not a PDF conversion.

JSWolf · Yesterday, 06:55 PM

Quote:

Originally Posted by Globe Trotsky

Thanks, as I said above, just checked and it was an EPUB, definitely not a PDF conversion.

How do you know it was not a PDF conversion before you got the ePub? Where did the ePub come from?

Karellen · Yesterday, 08:00 PM

@Globe Trotsky

Careful how you answer the question "Where did the epub come from". It has no bearing to your original question on how to fix the problem.
There be wolves among the sheep.

Sirtel · Yesterday, 08:15 PM

Quote:

Originally Posted by Karellen

@Globe Trotsky

Careful how you answer the question "Where did the epub come from". It has no bearing to your original question on how to fix the problem.
There be wolves among the sheep.

If it's a bad PDF conversion (and it almost certainly is, by the looks of it), there's no fixing it.

Karellen · Yesterday, 09:08 PM

Quote:

Originally Posted by Sirtel

If it's a bad PDF conversion (and it almost certainly is, by the looks of it), there's no fixing it.

Trying to fix via conversions, yea totally agree. Can't be done.

If you are prepared to read and fix at the same time, it can be done. Even easier if the original book is available as a reference.
A few regex to catch the split sentences are easy enough. It's all the other annoying missing italic, replaced characters, broken words and spurious code that are more difficult/impossible to bulk fix.

(not idea why an edit to my post caused a second post to appear)

DNSB · Yesterday, 09:14 PM

Quote:

Originally Posted by Karellen

Trying to fix via conversions, yea totally agree. Can't be done.

If you are prepared to read and fix at the same time, it can be done. Even easier if the original book is available as a reference.
A few regex to catch the split sentences are easy enough. It's all the other annoying missing italic, replaced characters, broken words and spurious code that are more difficult/impossible to bulk fix.

(not idea why an edit to my post caused a second post to appear)

Not to mention the issue with some ligatures (llama comes out as l ama for instance).

BetterRed · Yesterday, 09:19 PM

It's almost certainly a low quality OCR image scan of ink on paper (probably with an ancient version of ABBYY - probably pirated), that was saved as a PDF.

Professionally created PDFs using Acrobat, DTP (InDesign, even Quark), or WP (MS Word, LO Writer, WordPerfect) don't break paragraphs like that.

One way to deal with it, is to convert to txt, open with a decent text editor (e.g. Vim, Text Pad, Notepad++) and correct using regex. Then open the corrected text file in one of the WP apps mentioned above, style front-matter, headings, bibliography etc as appropriate and save as DOCX and get calibre to convert that to EPUB.

If you use Wordperfect you can save as EPUB directly, which does a better job of mapping its styling to the EPUB CCS.

There are also useful addins for Word - EPUB Tools (it is in the MR Workshop forum), and Transtools, which has an excellent Unbreaker tool.

BR

09-06-2025, 06:56 PM	#1
Globe Trotsky Junior Member Posts: 3 Karma: 10 Join Date: Sep 2025 Device: Kindle 10th Generation Paperwhite	Calibre tidy line breaks I have an annoying problem that even after converting books in Calibre editor, some are riddled with random line breaks. Can someone advise me on how to fix without having to manually go through the HTML editor. Is there a code/regex/plug in. TIA. Apologies if this should be on another thread. Attached Thumbnails

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09-06-2025, 08:53 PM	#3
Sirtel Grand Sorcerer Posts: 13,725 Karma: 242197301 Join Date: Jan 2014 Location: Estonia Device: Kobo Sage & Libra 2	A crappy conversion from PDF will always be a crappy conversion, unless you fix everything by hand, line by line. PDF is not a suitable format for conversion. TL;DR Don't convert from PDF if you can do it in any other way.

Yesterday, 06:52 PM	#5
Globe Trotsky Junior Member Posts: 3 Karma: 10 Join Date: Sep 2025 Device: Kindle 10th Generation Paperwhite	Thanks, as I said above, just checked and it was an EPUB, definitely not a PDF conversion.

Yesterday, 08:00 PM	#7
Karellen Wizard Posts: 1,634 Karma: 9500498 Join Date: Sep 2021 Location: Australia Device: Kobo Libra 2	@Globe Trotsky Careful how you answer the question "Where did the epub come from". It has no bearing to your original question on how to fix the problem. There be wolves among the sheep.

Yesterday, 09:19 PM	#11
BetterRed null operator (he/him) Posts: 21,856 Karma: 30277270 Join Date: Mar 2012 Location: Sydney Australia Device: none	It's almost certainly a low quality OCR image scan of ink on paper (probably with an ancient version of ABBYY - probably pirated), that was saved as a PDF. Professionally created PDFs using Acrobat, DTP (InDesign, even Quark), or WP (MS Word, LO Writer, WordPerfect) don't break paragraphs like that. One way to deal with it, is to convert to txt, open with a decent text editor (e.g. Vim, Text Pad, Notepad++) and correct using regex. Then open the corrected text file in one of the WP apps mentioned above, style front-matter, headings, bibliography etc as appropriate and save as DOCX and get calibre to convert that to EPUB. If you use Wordperfect you can save as EPUB directly, which does a better job of mapping its styling to the EPUB CCS. There are also useful addins for Word - EPUB Tools (it is in the MR Workshop forum), and Transtools, which has an excellent Unbreaker tool. BR

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