Thank you for your responses.
In the end I concluded that Calibre was indeed causing me hassles, so I kept the resized images file and used the top part of an opf file generated by InDesign that hadn't been near Calibre. I finally read the CanCrusher instructions properly so I could reassemble a Zip into ePub on Mac
. So it submitted fine. Hitch was on the money, and I had originally done the unzip/fiddle with images/try to rezip but screwed it up. At least Calibre gave be a bit of a look under the hood in the file so I learnt some things.
To address a couple of your points:
Yes, the authors were made aware of the limitations (by me). The book is basically designed to be viewed on iPads or other screen devices, not ePub readers. And I have tested it on those and it does look great. It had to be fixed layout ePub given PDF no longer supports video content and this is a design/art journal that has a lot of image/video (in fact, there is also a pdf version with links to all the video online). Why it isn't in a native app or responsive web only is another question (partly to do with it needing a permanent home, ISBN and DOI), but that is not my call.
This 4 million pixels issue is a
known InDesign weirdness and as I said, the file sizes are tiny (a small handful of kb) but the dimensions are enormous. Because in my file these are mostly being generated by text boxes (which are almost the page size and almost entirely transparent) that contain either link underlines, or coloured boxes on footnote superscripts that are basically small flat colour squares it really doesn't matter if they are smaller (because there's no real detail to loose) so just taking the dimensions under 2000x2000px is fine, if laborious, and still looks ok on screen.
So thanks for the help, got there in the end, just I wish I'd read the CanCrusher instructions in the first place
(I didn't see you're supposed to just drag the file onto the icon rather than opening it in the programme – duhhh).
