@catsknit,
dwanthny is correct and to add a little more detail...
The Sony x50 devices, in their wisdom, always extract the thumbnail from the book when a book is new. Developer
chaley tried many things to stop this happening. I helped with the testing. No magic method has been found and maybe never will be.
However, the 2 checkboxes in the Sony Device Interface plugin, shown in dwanthy's post above can improve things.
- This is what will happen if you check both boxes Upload separate cover thumbnails... and Refresh separate covers...
When you Send to Device some new books Calibre will also send thumbnails based on the Calibre covers. When you disconnect the Sony, it will throw away the Calibre thumbnails and extract its own from each book. When you simply reconnect the Sony to Calibre a second time, Calibre will send Calibre thumbnails again. This time they will 'stick'. This works for all Sony formats (epub, pdf, rtf, txt) whether they are DRM'd or not.
This is the 'easiest' way to keep your Sony thumbnails in sync with Calibre covers. However, if you have a large number of books on the Sony, refreshing the thumbnails every time you connect the Sony may be rather slow.
- This is what will happen if you check just one box Upload separate cover thumbnails...
When you Send to Device some new books Calibre will also send thumbnails based on the Calibre covers. When you disconnect the Sony, it will throw away the Calibre thumbnails and extract its own from each book. If you Send to Device a second time (only the books with a "wrong" thumbnail necessary) Calibre will send Calibre thumbnails again. This time they will 'stick'. This also works for all Sony formats whether they are DRM'd or not.
This is not as convenient but there will be no performance penalty each time you connect the Sony to Calibre.
My advice would be to try checking both boxes and see whether the performance is acceptable. If it isn't uncheck
Refresh separate covers...
On the other hand, if you only ever send non-DRM epubs to your Sony and these epubs have been created by Calibre with the correct cover, the thumbnail the Sony automatically extracts after the initial
Send to Device will be correct first time and you can leave both boxes unchecked.
Confusing, I know, but hope this explains the current situation.
*** Edit: As of Calibre v7.44 the problems detailed above have been fixed. Thumbnails are now created correctly first time ***