Quote:
Originally Posted by davidfor
GeoffR answered most of this. And the problem is probably to do with the difference in how Kobo treat books on the SD card. As the cover images are generated each time from the first page of the book, they have to be fixed in the book before sending them to the device. And this assumes as JSWolf pointed out that there is no DRM on the books.
The first thing to do is open one of the books with the bad cover and look at the first page. Does it look like how you would want the cover to look? That includes any white space down the sides of the image. When the cover image is generated, it will look exactly like this except for the page number at the bottom.
If the cover isn't dispayed how you want, it is generally a matter of changing the html code for the cover page. Usually you check the sizes for the image match the actual image used and then set options so the image is stretched to fill the screen. For the latter, you can stretch to fill both ways which might distort the cover, or stretch one way keep the aspect ratio of the image correct. The exact code you use depends on this.
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As near as I can tell, my Kobo does not display the covers from an ebook in the internal storage any differently from a cover from an ebook in the external storage. There is a delay when the temporary images and thumbnails need to be generated but the cover as displayed looks no different whether in sleep/power down or by scrolling back to the first page of the ebook -- I've played with using other locations in content.opf but the results don't seem any different so I don't bother with them anymore.
I use the same bit of HTML to generate the cover no matter where I am placing the book, the only change needed is from 510x680 to match the resolution of the cover image.
<div>
<svg xmlns="http://www.w3.org/2000/svg" height="100%" preserveAspectRatio="xMidYMid meet" version="1.1" viewBox="0 0 510 680" width="100%" xmlns:xlink="http://www.w3.org/1999/xlink">
<image height="680" width="510" xlink:href="../Images/cover.jpg"></image>
</svg>
</div>
This can result in letterboxing (horizontal) or pillarboxing (vertical) bars if the orginal image is not in a 4x3 format but I'm willing to live with them rather than a distorted apect ratio which bothers me even more.
I still suspect that removing the books from the internal storage before copying them to the external storage was not done properly which can lead to all kinds of nasties with database corruption. Been there and done that, got the factory resets to show for it.
Regards,
David