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Old 10-12-2024, 11:43 PM   #1756
DNSB
Bibliophagist
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Posts: 47,053
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Join Date: Jul 2010
Location: Vancouver
Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos
Quote:
Originally Posted by girlsoconfusing View Post
I tried converting my full library to ADE and made sure the settings were identical for each book but now all of them are showing drastically different page counts than what's displayed in Calibre.

Somewhere Beyond the Sea:
Calibre: 337 pages
Pocketbook: 967 pages

The Way of the Kings
Calibre: 1041 pages
Pocketbook: 3523 pages

Slow Horses:
Calibre: 274 pages
Pocketbook: 670 pages

Is it normal that the page count is this different?
Yes. The only page measurements with any reliability and consistency between devices are the Adobe Synthetic Page Number algorithm for ePubs and Amazon APNX for Kindle format. For ePub, using the ASPN algorithm will give the same page number regardless of screen size, font size, line spacing, margins etc. Other methods of determining pages that use screens to measure pages have the sole advantage that you get 1 page per screen so your page count will vary with font size, line spacing, margins, basically anything that changes the amount of text that will fit on a screen.

Please note that both the consistent algorithms will give page numbers anywhere on the page.

Even though I will admit to be very amused by people worrying about the page numbers on a reflowable format where font size, line spacing, margins etc. are more or less under the users control.

The only use I have for the CountPages plugin is to give me an approximate idea of how long it will take to read a book. You may want to check many previous threads on page counts such as How does the kobo calculate book page counts? from 2015.

BTW, calibre uses ~1024 characters as a page, the fast APNX uses 2300 while the accurate one used by CountPages looks at characters and paragraphs. Adobe algorithm is a bit of a weirdo since it uses 1024 compressed characters as per the following from Adobe:

Quote:
When page map is not available in the document, Adobe Digital Editions will synthesize a page-map based on the document content. The approach used is the following:
  1. Determine a compressed byte length of each resource which is referenced in the spine, subtracting any known encryption overhead (IV size)
  2. Assume that there is a page for each 1024 bytes in each resource, rounding up to the nearest whole number of pages for each resource
  3. To map page breaks into a resource, use the number of pages for the resource as determined in step 2, count the number of Unicode characters in the resource; distribute synthetic page breaks in the resource evenly between the characters by dividing the number of characters by the number of pages; if the number of characters don’t divide evenly among the pages, round the number of characters per page up and let the last “page” contain less characters than the rest.

Last edited by DNSB; 10-12-2024 at 11:57 PM.
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