Touch Calibre, Kobo Touch & Cover Artwork

[Canorka]

Woo hoo. Configuring the driver to always send covers has solved the white margins problem on my Mini. Thanks for the tips!

[theboyk]

Well, I loaded the ePub you sent me and the cover is still vertically stretched on the Kobo home screen. I ran multiple tests and it continues to be based on what the settings are for my margins.

I also looked at the cover files in the images directory, and those files were all the correct aspect ration. So, it seems like the Home Screen itself is distorting the image it's using on-the-fly.

That said, I started looking at Kobo Store-based purchases and they were doing the same thing—the covers are either vertically stretched on the Home Screen or they're horizontally squished on the sleep/off screen (it all depends on the original image and which is correct).

Below I've linked to an example of the cover to a book I've purchased on the Kobo. On the left is the N3_FULL version of the cover. On the right is the N3_LIBRARY_FULL version of the cover (scaled up to match the 600px width of the N3_FULL cover). As you can see, the N3_FULL version of the cover is horizontally squished.



So, I did a little more testing on the files themselves and it turns out that the N3_FULL version is not used for both the Home Screen and the Sleep Screen—it's only used for the Sleep Screen. It's the N3_LIBRARY_FULL version that's used for the Home Screen. To determine this, I edited the two versions of the cover files, adding the text "FULL" to the N3_FULL version and "FULL LIB" to the N3_LIBRARY_FULL version. And these are the results on the Kobo:

SLEEP SCREEN (N3_FULL)


HOME SCREEN (N3_LIBRARY_FULL)


So, from all my testing, I just don't see a way to get proper aspect ratios on both the Home and Sleep screens (unless you have your margins set to zero)—one will be either stretched or squished, depending on the original cover.

Thoughts?

[scoobertron]

I have had ongoing frustrations with this as well. Two approaches have worked for me. Editing the epub to fix the margins for the cover page makes the sleep screen correct, but I am not sure about the homescreen. A slightly more sledgehammer approach is to manually replace all the images in the kobo images directory with corrected versions. This is probably only workable if it can be scripted (I have a script that generates identical covers for books, modeled on the old penguin classics, which makes it a bit easier as I don't have to worry about messing with the original covers)

[theboyk]

I tried the manual replacement of images, but even then they were getting vertically stretched on the Home Screen. If you look at the image in my previous post (the last one)—the cover for Leviathan Wakes was manually placed onto the Kobo with a size of 600*800, yet it's still vertically stretched on the screen.

Really, at this point, it doesn't look like there's an easy fix, so I'll just have to live with the stretched covers. I mean, if books purchased from the Kobo store do it, that just might be the way it works.

I have a theory. In the past, Home Screen images were perfect ratio images—now, if you check their scale, when you scale the width to 600px, the height is about 869px (I can't remember the exact number). As well, the covers look correct at this new size as it's closer to a "physically" book cover size, and the images used on the Sleep screen are actually squished to fit (you can tell by looking at the Os in words, or comparing to the read printed books). So, I have a feeling Kobo is moving to this new size for book cover and the images on the Sleep screen will be slightly squished (because of the "fill screen" option).

Most of the time it's not super noticeable, but on something like the Steve Jobs bio, it's really obvious because the cover is his face—and distorting a face is a very obvious thing when it's done, even if done slightly.

That's just my opinion though...

[davidfor]

Originally Posted by theboyk

Well, I loaded the ePub you sent me and the cover is still vertically stretched on the Kobo home screen. I ran multiple tests and it continues to be based on what the settings are for my margins.

That is correct if you are letting the device generate the image. If you send them from calibre, it doesn't.

I also looked at the cover files in the images directory, and those files were all the correct aspect ration. So, it seems like the Home Screen itself is distorting the image it's using on-the-fly.

That said, I started looking at Kobo Store-based purchases and they were doing the same thing—the covers are either vertically stretched on the Home Screen or they're horizontally squished on the sleep/off screen (it all depends on the original image and which is correct).

Below I've linked to an example of the cover to a book I've purchased on the Kobo. On the left is the N3_FULL version of the cover. On the right is the N3_LIBRARY_FULL version of the cover (scaled up to match the 600px width of the N3_FULL cover). As you can see, the N3_FULL version of the cover is horizontally squished.

From a quick look, all my Kobo supplied cover images are the same aspect ratio. But, they are 2:3 rather than the 3:4 use for sideloaded books.

So, I did a little more testing on the files themselves and it turns out that the N3_FULL version is not used for both the Home Screen and the Sleep Screen—it's only used for the Sleep Screen. It's the N3_LIBRARY_FULL version that's used for the Home Screen. To determine this, I edited the two versions of the cover files, adding the text "FULL" to the N3_FULL version and "FULL LIB" to the N3_LIBRARY_FULL version. And these are the results on the Kobo:

SLEEP SCREEN (N3_FULL)

Firstly, that is not the choice of images used here. The N3_FULL is for both home screen and the screensaver. I have done similar tests to prove this.

I just measured the box around the image. On my screen it is 63mm x 98mm. That is an aspect ratio of about 63%

HOME SCREEN (N3_LIBRARY_FULL)

Now you really have me. How did you get that home screen? Mine has always used the five book mosaic:


With the differences we are seeing, could you check the device information and post the software version. I won't post mine as I am using a beta. But, when using the released versions, I have always had the mosaic.

So, from all my testing, I just don't see a way to get proper aspect ratios on both the Home and Sleep screens (unless you have your margins set to zero)—one will be either stretched or squished, depending on the original cover.

I think you are right. The aspect ratios of the different places the images are used don't match. The screen is 3:4 but the others look like they are 2:3.

One thing that I have just realised is that we have been talking about slightly different things. For the home screen, I have been looking at filling the box for each screen while you were more concerned about the correct aspect ratio. I'll admit that I assumed the covers on the home screen were the correct aspect ratio and the problem was getting the image generated to this. But, as the aspect ratios used are different in different places and the same image is used, it is an impossible quest. For the mosaic I have, it doesn't look to bad. For the two book home screen you have, it is a lot more noticeable.