Calibre side-loaded book covers?

[trcm]

Some books will display the cover, some refuse to at all, and some display momentarily only to disappear after a minute.

What are the requirements to get Calibre side-loaded book covers to consistently show up on a Kindle PW4 ?

• Do book formats matter (eg. mobi / azw3 / kfx) ? No.
• Do book ids matter (eg. must I set/unset isbn / mobi-asin) ? No.
• Do book cover sizes matter (eg. Is there a maximum resolution) ? YES!
• Under what circumstances can/does the Kindle download it's own covers from Amazon ? Unclear, probably based on book IDs.
• Must I embed the cover image somehow (eg. I've read about epub to epub conversions) ? No.

[Lizj1]

I always set the cover size to 520x800, then polish to embed the cover in the file, and my preloaded covers always show up. I use AZW3 format but I think mobi works too.

[ilovejedd]

• Do book formats matter (eg. mobi / azw3 / kfx) ?
  
  USB sideloading using Calibre send to device should upload the covers separately (to a hidden <drive>:\system\thumbnails folder) so format shouldn't have been an issue. It's only when using email to Kindle or copying via file manager/system when formats matter. Iirc, the Kindle will only read embedded covers from MOBI old [PDOC]. Caveat, you lose a lot of advanced features (e.g. boldness, custom fonts, etc). Might work for MOBI both, too, but it's been a while since I last tested that so I've forgotten what the results were.
  
  
• Do book ids matter (eg. must I set/unset isbn / mobi-asin) ?
  
  Same as above. Shouldn't matter when using Calibre send to device.
  
  
• Do book cover sizes matter (eg. Is there a maximum resolution) ?
  
  If there is, I haven't managed to hit it yet. I think all my book covers are at or below 1200*1600, though.
  
  
• Under what circumstances can/does the Kindle download it's own covers from Amazon ?
  
  Iirc, it worked for AZW3 with matching/correct Amazon ASIN. Never tried MOBI or KFX.
  
  
• Must I embed the cover image somehow (eg. I've read about epub to epub conversions) ?
  
  As mentioned, reading from embedded covers only works for MOBI old [PDOC] (maybe MOBI both, too).

[trcm]

Originally Posted by Lizj1

I always set the cover size to 520x800, then polish to embed the cover in the file, and my preloaded covers always show up. I use AZW3 format but I think mobi works too.

What do you mean by 'polish' please?

[Lizj1]

There is a Polish function you can add to the toolbar at the top of the screen, and o e of the tasks it can do is embed the cover into the book file. I'm away from my pc at the moment, but I think you need Preferences, Look and Feel, Toolbar, but I'll check when I get back.
Liz

[Lizj1]

Hi again.

To add "Polish books" to your toolbar, click on Preferences; Toolbars & menus, then select "The main topolbar" from the drop down menu.

Find "Polish books" in the list of Available actions on the left, and add it to Current Actions on the right.

If you can't find it, you may have to add the plugin first, but I'm pretty sure it is available by default.

Polish Books only works on epub and azw3 formats, I think, but if you want to use mobi., you can reconvert to mobi from the new epub or azw3 to get the cover embedded in the mobi.

Hope this helps, Liz

[Paperbackstash]

Some of my covers wouldn't show in the Mobi format, so I always use calibre to change to azw3 and haven't had the same issues. As long as the kindle is not indexing anymore, the covers should show. My covers would stay missing for awhile on many books when I sideloaded a lot of books at once and it stayed indexing behind the scenes.

[stumped]

in my experience, cover size matters. 600x 800; 600x900 both work .
too large, and possibly too small - will fail to show.
so i use the calibre resize cover plug in
having all covers the same size will improve "shelves" display in some epub readers also

[trcm]

I removed all books from my Kindle, resized the covers in Calibre using the 'Resize Covers' plugin to 600x800, and sent them back to my Kindle. A great success, with all books now displaying their covers correctly!

I later connected to WiFi and the Kindle automatically replaced some of the covers with what appear to be differently proportioned (mostly taller?) versions of the ones I chose.

Thank you all for your suggestions, especially to @stumped !

Now if only my Audible books showed their covers too :/

[stumped]

Originally Posted by trcm

...

I later connected to WiFi and the Kindle automatically replaced some of the covers with what appear to be differently proportioned (mostly taller?) versions of the ones I chose.
../

I leave my wifi off, on Paperwhite, so I had not seen that.
it is probably fixable, if it bugs you.
you would need to remove the ASIN from the book metadata, so that amazon cannot match it
I think the match is done with ASIN, not with title + author but others may know for sure

[ilovejedd]

Originally Posted by stumped

I leave my wifi off, on Paperwhite, so I had not seen that.
it is probably fixable, if it bugs you.
you would need to remove the ASIN from the book metadata, so that amazon cannot match it
I think the match is done with ASIN, not with title + author but others may know for sure

Yup. It's by ASIN. If you go to the hidden folder in <Drive:>/system/thumbnails/ you'll see they're all named by ASIN. Although I have no idea what algorithm Amazon uses for books without ASIN. Maybe timestamp?

Aspect ratio of Amazon covers tend to be 2:3 so I keep my Calibre covers in that aspect ratio as well (usually 600x900 or 800x1200).