I am trying to batch process (say, sharpen) most images in a epub and keep everything else as it is.
Approaches -
1.The in-built editor allows me to export all images, but only replace one-by-one. So, that won't work.
2. I thought since epub is just zipped folder - I'll extract all content, process files, then zip it up again. This sort of works, but I am facing this problem.
On mac, using in-built archive tool and Keka both - if i rename epub to zip, extract it as a folder, again zip it and rename to epub, the edit epub tool then does not recognise this epub. The error is - "No META-INF/container.xml in epub". I have verified that this file exists in the zip. Both ebook conversion and ebook-viewer still works with this file but not ebook-edit.
What can be a possible reason for this? Is there a unpack and repack tool for epub within calibre (or plugin)?
I saw some old post about tweak epub/unpack book functionality, but I can't find it.
Sample file -
https://www.swisstransfer.com/d/6ba0...f-eed865eaacd8