Anyone know how to find a specific book cover in /system/thumbnails?

[Siavahda]

I want to replace the cover image for a specific book. (Removing the ebook and reloading it onto my kindle with the correct cover would mean losing my highlights and notes, so I'd rather not do that.) But I can't figure out which of the MANY image files in /system/thumbnails (or amazon-cover-bug) is the one I want, short of manually going through them all one by one.

Is there anything in the cover/image file names that identifies which ebook it's the cover for? They all have names like 'thumbnail_0a513f83-1cf4-4863-85c8-2b0cb70d0575_EBOK_portrait', but I don't see any connection between those numbers and the name of the ebook file.

Thoughts? Suggestions?

[shamanNS]

Those numbers are values of book's ASIN that Calibre generated and filled out.
You would need to use a computer to find out what value is used for that particular book file.

I'm not sure if Calibre itself offers a built-in way of accessing that metadata field value (perhaps it would populate the "Ids" section with "mobi-asin" identifier on book import??) but something like MobiMetaEditor should get that job done:

https://www.mobileread.com/forums/sh...98&postcount=1


When you have the ASIN value you can just do a search inside "thumbnails" folder. The new cover image file must use that exact filename.

[Siavahda]

I have absolutely no experience/knowledge with java, so I'm not sure I can make the Mobi MetaEditor work. Thank you for the suggestion though!

I did find the ASIN from Calibre's metadata for a book, but that didn't find me a cover file. Alas!

[shamanNS]

Does that particular book have an actual cover thumbnail image displayed on Kindle's homescreen or is it using a generic image that Kindle uses when the thumbnail image is missing?

If it is showing you a generic, "placeholder" image then the thumbnail file is missing (thus can't be found using search) and you would need to add an image with a correct filename. The filename "template" looks like this:
thumbnail_ASIN_EBOK_portrait.jpeg

As for Java & MobiMetaEditor: all you need to to is download install Java JRE (if your computer doesn't already have it installed) and then just open / double-click on MobiMetaEditor ".jar" file and it should open the UI window where you proceed to select the mobi or azw3 file for which you want to read the metadata, and then look at ASIN.

[Siavahda]

It's the generic image. I only belatedly realised that this means there's no cover image at all (I thought the generic image was, you know, an actual image generated by the kindle or something).

I tried creating a cover file with that name layout, but the ebook itself doesn't have the ASIN in its metadata (as far as I can see on Calibre) and I'm permanently on airplane mode, so I don't think the kindle can check the asin against Amazon. As-is, putting the new cover image into \system\thumbnails didn't do anything. (But then, I'm not sure the ASIN is the only thing that goes into the cover image name? Those strings of numbers are a lot longer than any ASIN I've ever seen.)

I'm poking at the MobiMetaEditor now... I'll let you know how it goes!

[shamanNS]

For Calibre generated Kindle book files Calibre puts its own GUID identifier as a value in place where for Kindle Store "retail" books would have an actual B___ ASIN id.
Because both ASIN & cdeType with value "EBOK" need to be set in order for Kindle to treat "sideloaded" book as a "Book" and not as a "Doc" (Doc = cdeType "PDOC") Calibre started doing that years ago.


Airplane mode isn't your problem. Missing files in /system/thumbnails is.

Or maybe you also have book files that are azw3 format + cdeType "PDOC" (you can check that also with MobiMetaEditor) + older Kindle firmware combination that IIRC would refuse to use even existing thumbnail image file.

[Siavahda]

Is there a way to find a book's GUID/UUID within Calibre? It's not in the edit metadata section, as far as I can tell.

The MobiMetaEditor worked BEAUTIFULLY! Thank you so much for pointing me to it! (And nudging me to try anyway when I was intimidated by it.) There were just a handful of books it didn't work on, for some reason, but I'm hoping I can manually create cover thumbnails for those, especially since the MobiMetaEditor shows UUIDs!

[Siavahda]

Okay, I found how to see UUID (right click book title in calibre, view book details), but now I'm confused that MobiMetaEditor claims several books have no UUIDs, when I can see that they do in Calibre.

Just creating a cover file with the UUID isn't working - the kindle doesn't seem to register it as a cover. Think I need to follow the instructions here and see if they work to get the covers on these last few books.

(Documenting what I'm doing for anyone who might find this thread in the future.)

[Siavahda]

Okay, so these are the instructions

• Select the book without UUID in Caliber
• Choose "Convert Books / Convert Separately".
• Select a different format than the one the book currently has and convert it
• Remove old book formatting
• Convert the book to old format (if desired)
• Delete the format you first converted it to
• Send the book back to your Kindle

I don't know what 'remove old book formatting' means. And 'Send the book back to your Kindle' would erase the notes etc that I'm trying to save on the original ebook file.

Anyone have any advice here?