So I'm struggling to get this to work no matter what I try.
My last attempt was to recreate the epub anew with a new file name, unzip it, create a new 'Images' folder in there and place 'gold-aureus.jpg' in there. The CSS is amended to point to 'Images/gold-aureus.jpg' and the opf file has this line added to it too:
Code:
<item id="gold-aureus.jpg" href="Images/gold-aureus.jpg" media-type="image/jpeg"/>
I re-zip the file and change the extension back to epub.
When I open it in Sigil, the image is now in the Images section (left-hand panel), but the image still doesn't appear.
Mend xhtml source on open and save are both checked in the preferences.