MobileRead Forums - View Single Post - Calibre & Covers: Adding books through Calibre vs dragging and dropping?

davidfor · 06-08-2014, 05:34 AM

There are a few things going on here that aren't completely connected.

Firstly, for epubs and PDF on the Kobo devices, the device generates the cover from the first page of the book. This is used wherever the device needs to display it. If the book is on the main memory, it also saves the cover. The saved cover is read by the driver to display. If the books is on the SD card, the device does not save the generated cover and hence it isn't there for calibre to display.

If you use calibre to sideload the books, there is an option in the Kobo driver to send the cover to the device. The cover is generated at several sizes and put where the device will use it. This works for both the main memory and SD card. The device will use stored cover for books on the SD card, it just doesn't save them there if it does the generation. In this case, calibre should find a cover to display on the device list.

Calibre can also store a cover thumbnail in the file metadata.calibre on the device. This file is used to match the books on the device with the calibre library. When you send a book using calibre, the details are stored in this file to ease the matching when the device is next connected. If a book gets on the device by some other method, calibre will try to match the book if it can and put the details in this file for the future. For books that aren't automatically matched, you can do this manually when viewing the device list using the method eschwartz mentioned.

Sending a cover from calibre will likely look better on the device than letting the device generate it. I think calibre does a slightly better job of doing this, plus it is working from the cover stored in the calibre library rather than generating the first page. The latter might result in a distorted image depending on how the book displays the cover image.

I think that answers the questions raised. But, I won't be surprised if I missed something. Or have explained something badly. I'll be happy to try again if you need it.

06-08-2014, 05:34 AM	#13
davidfor Grand Sorcerer Posts: 24,905 Karma: 47303824 Join Date: Jul 2011 Location: Sydney, Australia Device: Kobo:Touch,Glo, AuraH2O, GloHD,AuraONE, ClaraHD, Libra H2O; tolinoepos	There are a few things going on here that aren't completely connected. Firstly, for epubs and PDF on the Kobo devices, the device generates the cover from the first page of the book. This is used wherever the device needs to display it. If the book is on the main memory, it also saves the cover. The saved cover is read by the driver to display. If the books is on the SD card, the device does not save the generated cover and hence it isn't there for calibre to display. If you use calibre to sideload the books, there is an option in the Kobo driver to send the cover to the device. The cover is generated at several sizes and put where the device will use it. This works for both the main memory and SD card. The device will use stored cover for books on the SD card, it just doesn't save them there if it does the generation. In this case, calibre should find a cover to display on the device list. Calibre can also store a cover thumbnail in the file metadata.calibre on the device. This file is used to match the books on the device with the calibre library. When you send a book using calibre, the details are stored in this file to ease the matching when the device is next connected. If a book gets on the device by some other method, calibre will try to match the book if it can and put the details in this file for the future. For books that aren't automatically matched, you can do this manually when viewing the device list using the method eschwartz mentioned. Sending a cover from calibre will likely look better on the device than letting the device generate it. I think calibre does a slightly better job of doing this, plus it is working from the cover stored in the calibre library rather than generating the first page. The latter might result in a distorted image depending on how the book displays the cover image. I think that answers the questions raised. But, I won't be surprised if I missed something. Or have explained something badly. I'll be happy to try again if you need it.