Clara HD Itty Bitty Thumbnails

Calenorn · 08-12-2018, 05:51 PM

Hello Kobologists,

Here's a trivial question: Why do some of the thumbnail cover images (on home screen and collections) appear at 1/4 size? Is there a preferred cover image size (say, 400 x 600 pixels)? How can I tweak the offending epubs to make them create normal thumb images?

Many thanks!

C.

davidfor · 08-12-2018, 07:55 PM

Exactly how the cover images are made depends on the type of book. But, the complaint is most likely to mean the books are epubs.

For epubs, the device renders the first page of the book and saves a copy of that. What I expect is happening is that the cover in the book is on the first page, but doesn't fill the page. And when the device generates the cover image, you get what you describe. You would need to look at the first page to see if this is correct.

There are several ways to fix this. The best, to me, is to embed the cover image on the first page using an SVG wrapper that sizes the image to fill the screen. I do this using calibre. It can generate the code for you in a number of different ways (during a conversion, Polish books, using Modify ePub plugin or using the editor). There is probably other code to achieve the same thing, but, this is the way I do it.

You can also use the drivers to generate the cover images when sending the books to the device. Whether this is better depends on your viewpoint. But, it does generate a smaller image for the full sized cover, so there is a space saving.

As to the cover image size, I just get the best image I can find and let the software of the reader resize it as needed. Strictly, a cover the same size as the resolution of the device is probably best. But, if you get a higher resolution device, then it won't show up as well there. And as you are stepping up from a Mini (600x800) to a Clara HD (much higher and I don't remember exactly what), you would be hitting this now.

Calenorn · 08-12-2018, 08:12 PM

Thanks, David. It's just that some covers (prepared the same way, as far as I can tell) show up small and others do not. I was wondering what makes the difference.

Calenorn · 08-14-2018, 07:14 AM

So I used Sigil to re-add the covers of the offending volumes and they work fine now. No issue with the Clara.

Transferring my collection to the new device is revealing some volumes that need a bit of fixing-up. But that's part of the fun.

08-12-2018, 05:51 PM	#1
Calenorn Brash Fumbler Posts: 1,159 Karma: 8710811 Join Date: May 2013 Device: NST, Kobo Mini	Itty Bitty Thumbnails Hello Kobologists, Here's a trivial question: Why do some of the thumbnail cover images (on home screen and collections) appear at 1/4 size? Is there a preferred cover image size (say, 400 x 600 pixels)? How can I tweak the offending epubs to make them create normal thumb images? Many thanks! C.

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08-12-2018, 07:55 PM	#2
davidfor Grand Sorcerer Posts: 24,907 Karma: 47303748 Join Date: Jul 2011 Location: Sydney, Australia Device: Kobo:Touch,Glo, AuraH2O, GloHD,AuraONE, ClaraHD, Libra H2O; tolinoepos	Exactly how the cover images are made depends on the type of book. But, the complaint is most likely to mean the books are epubs. For epubs, the device renders the first page of the book and saves a copy of that. What I expect is happening is that the cover in the book is on the first page, but doesn't fill the page. And when the device generates the cover image, you get what you describe. You would need to look at the first page to see if this is correct. There are several ways to fix this. The best, to me, is to embed the cover image on the first page using an SVG wrapper that sizes the image to fill the screen. I do this using calibre. It can generate the code for you in a number of different ways (during a conversion, Polish books, using Modify ePub plugin or using the editor). There is probably other code to achieve the same thing, but, this is the way I do it. You can also use the drivers to generate the cover images when sending the books to the device. Whether this is better depends on your viewpoint. But, it does generate a smaller image for the full sized cover, so there is a space saving. As to the cover image size, I just get the best image I can find and let the software of the reader resize it as needed. Strictly, a cover the same size as the resolution of the device is probably best. But, if you get a higher resolution device, then it won't show up as well there. And as you are stepping up from a Mini (600x800) to a Clara HD (much higher and I don't remember exactly what), you would be hitting this now.

08-12-2018, 08:12 PM	#3
Calenorn Brash Fumbler Posts: 1,159 Karma: 8710811 Join Date: May 2013 Device: NST, Kobo Mini	Thanks, David. It's just that some covers (prepared the same way, as far as I can tell) show up small and others do not. I was wondering what makes the difference.

08-14-2018, 07:14 AM	#4
Calenorn Brash Fumbler Posts: 1,159 Karma: 8710811 Join Date: May 2013 Device: NST, Kobo Mini	So I used Sigil to re-add the covers of the offending volumes and they work fine now. No issue with the Clara. Transferring my collection to the new device is revealing some volumes that need a bit of fixing-up. But that's part of the fun.

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