Quote:
Originally Posted by ratinox
Faux pages don't tell you this. They present a multiple of some count of characters from some arbitrary position. And the accuracy is questionable. For example, faux page 32 in an ebook with only text and faux page 32 in an ebook with 16 full page illustrations up to that point won't line up.
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Different books, different numbers. If the book does not contain page number mapping (either page-map or pagelist), what the Adobe epub synthetic page number algorithm offers is that no matter what device you read on, the
same epub file will have page 32 will start at the same point. As in one of my daughter's university textbooks where synthetic page 156 was the same on her iPad, a Kobo ereader and ADE on her computer. The professor gave his page references in 3 forms, hardcover edition 6 page numbers, Adobe epub edition 6 page numbers and a search string for other devices. Admittedly, most of his references were more like "Read Chapters 7 to 10 for Monday and be prepared to discuss the content".
As for your example, do you have—at hand—an example of two pbooks where the page numbers in the text only version lined up with the page numbers in the illustrated edition with 16 full page illustrations in the first 32 pages? Preferably two editions with the same font/font size/line and/or paragraph spacing, margins/etc and a page number assigned to each of the full page illustrations.
For those who haven't stopped reading by now, here's the quote from the Adobe EPUB Best Practices ebook (version 1.0, March, 2008):
Synthetic page names
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:
- Determine a compressed byte length of each resource which is referenced in the spine, subtracting any known encryption overhead (IV size)
- 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
- 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.