Touch Calibre, Kobo Touch & Cover Artwork

[theboyk]

Does anyone know if it's possible, using Calibre, to properly send cover artwork to the Kobo Touch?

I'm trying to get the following working:

- cover artwork fills screen @ proper aspect ratio when device sleeps/off
- cover artwork @ proper aspect ration when on Home Screen (which seems different than the aspect ratio when the device sleeps/off)
- no borders used on cover artwork

I have gone through the many threads in these forums as well as numerous Google searches and the best I can come up with is:

- start with a custom cover @ 600px x 800px
- convert to ePub via Calibre
- export the ePub
- delete the ePub from Calibre
- load of a virtual instance of Windows 7 (I'm on a Mac) and run the ePub through ePubFixer
- re-import the ePub into Calibre
- load the ePub onto my device

Using the above method, I get:

- cover artwork fills screen @ proper aspect ratio when device sleeps/off
- no borders used on cover artwork

But, I'm still getting incorrect aspect ratios (ie. the image is vertically stretched) when book covers are displayed on the Home Screen. I could live with this, but even getting this far is way too much work just to get the cover to display properly sometimes.

Does anyone know a better way of doing this? Is it possible to even get a cover that displays properly on both the sleep/off screen AND Home Screen?

Thanks,
Kristin.

[Roadbug]

Some thoughts:

1. Calibre has a box you need to click to keep the proportions of the cover. Unchecked, this might explain why your covers are deformed. In a Mac, go to: Preferences; Conversion; Output options; EPUB output and select the box with "preserve cover aspect ratio" (or something like this).
2. I am not sure if 600 x 800 pixels is the right aspect ratio for the KT. Never bothered to look for it in the manual, assuming that the manual contains this information.
3. I have used Calibre to change the covers successfully on my Mac. I have never used ePubFixer, but there might be another little box tucked away somewhere that controls the proportions of covers. Covers created using Calibre appear correctly on my KT when sleeping or turned off.

[theboyk]

Clicking "keep the proportions of the cover" results in white borders added, usually to the left/right edges. I think that has something to do with the way firmware 2.x generates the various cover images files based on margin settings when the ePub is processed.

So, as far as I can tell, there's no way to get proper covers onto the Touch (i.e.. proper proportions, without any distortion/scaling, and without white borders)?

[davidfor]

What output profile are you using in calibre? As you are creating correctly sized images for your cover use "Tablet" or something that doesn't resize the covers. With that, you should be able to cut back to just the conversion in calibre.

Once the epub is on the device, what does the first page look like? This is what will be used as the cover. If your reading settings have margins, then they will be used on the first page and the covers.

If the above doesn't work, I am curious about what is happening. Can you post an epub after the conversion for me to look at? If you can create one with just the cover page, that should bypass any copyright considerations.

Having said that, have you looked at the configuration for the Kobo Touch driver in calibre? You need to set two options: "Upload covers for books" and "Always upload covers". With these options, the driver generates the covers at the appropriate sizes and copies them to the device. It uses the cover in the library to do this. The covers are stretched to the sizes, but if you have 600*800 covers already, they will be OK.

[theboyk]

I'm using the Kobo Reader output profile. Is that not correct?

Hmmm, I've never seen the "upload covers for books" and "always upload covers" options—where do I access those? That might be what I'm missing!

I've only tweaked my output settings—didn't know there were driver settings as well?!

I'll look for that and report back!

[davidfor]

Originally Posted by theboyk

I'm using the Kobo Reader output profile. Is that not correct?

I think the options in there are for the original Kobo device. I haven't checked them against what should be used for the Touch. In any case, using this profile will resize the images to a preset size. Using the Tablet profile will leave the images untouched. Personally, I like the latter as it means the device gets to decide how to display images.

Hmmm, I've never seen the "upload covers for books" and "always upload covers" options—where do I access those? That might be what I'm missing!

I've only tweaked my output settings—didn't know there were driver settings as well?!

I'll look for that and report back!

Have a look at https://www.mobileread.com/forums/sho...d.php?t=193184 and https://www.mobileread.com/forums/sho...d.php?t=192863. The first one is simpler but with emphasis on shelves. The second one has all the gory details.

[davidfor]

theboyk sent me a sample book to look at.

The first thing I did was open it in the calibre viewer and I immediately knew what was wrong. The viewer opened so the page area wasn't in a 3:4 ratio. The cover was stretched. The answer is that you have preserveAspectRatio="none". This means if the image is resized, the aspect ratio is not kept. When the page is displayed on the device, it will be stretched for two reasons: the footer takes up some space and the margin settings you have in the reader.

Changing to use preserveAspectRatio="xMidYMid meet" will fix the problem.

There was some discussion of this in the last few days. Have a look at https://www.mobileread.com/forums/sho....php?p=2301231.

[theboyk]

Are you referring to the checkbox on the conversion settings to "keep aspect ratio"? I've tried with that option checked, and with it unchecked, and I get the same results. I only sent you one of the test conversions. I can send the other, if it might help?

Also, the issue I'm having isn't with the image when viewing the ePub itself, but rather with the smaller cover image used in the "collage" of covers on the home screen (the main screen on the Kobo that to return to when you hit the home button). It's this screen where the covers are stretched.

Why would they be stretched on the home screen?

[davidfor]

Originally Posted by theboyk

Are you referring to the checkbox on the conversion settings to "keep aspect ratio"? I've tried with that option checked, and with it unchecked, and I get the same results. I only sent you one of the test conversions. I can send the other, if it might help?

With that option checked, the cover page is generated with preserveAspectRatio="xMidYMid meet". That is what is needed to prevent the cover image being stretched out of shape. I did the converstion myself to check all this.

To see what I mean, open the version you sent me with the calibre viewer. The cover will fill the first page. When you resize the viewer, the cover will be stretched to fill whatever size the viewer is.

Then try a version with "Keep aspect ratio" checked. The cover will be displayed with the correct aspect ratio. It will be size to fill either the vertical or horizontal space depending on the size of the viewer. Resizing the viewer will resize the image keeping the aspect ratio (though I had to scroll of the page and back for this to happen).

Also, the issue I'm having isn't with the image when viewing the ePub itself, but rather with the smaller cover image used in the "collage" of covers on the home screen (the main screen on the Kobo that to return to when you hit the home button). It's this screen where the covers are stretched.

Why would they be stretched on the home screen?

If you let the device to generate the cover images, then what you see on the home screen will be what you see on the first page of the book on the device. This includes whatever margins you have set the device to use.

What has just occurred to me is that the cover image might not have been updated. The device generates them the first time it sees the book. If you replace the book, it doesn't regenerate the covers. You need to remove the the book and and then put it back.

What I have just done to get this looking correct on my Touch is:

- Opened the version of the book.
- Open the font settings and set the margins to none
- Close the book and deleted it
- In calibre, converted the book with "Keep aspect ratio" checked
- Connected the Touch
- Sent the book to the Touch
- Disconnected the Touch

When the home screen was displayed, the cover filled the box with no white bars.

[theboyk]

Yea, I always delete the books before sending replacements. I will agree with you that I can get correct aspect ratios only if I set my margins to zero before sending books to the Kobo, otherwise, the Kobo will stretch the book based on margins. Have to reset margins to zero before each import isn't really an efficient process—it works, but not ideal.

I thought Calibre was sending the cover images though? Is there no way to send the image for the home screen?

[davidfor]

Originally Posted by theboyk

I thought Calibre was sending the cover images though? Is there no way to send the image for the home screen?

Calibre is supposed to send them if you have the correct options selected in the driver. For what you are doing you need both "Upload covers for books" and "Always upload covers" checked. Exactly what cover images are created depends on the version of calibre and the devices firmware.

[theboyk]

I'm on the latest version of Calibre, and I'm running the latest available version of Kobo firmware. And I have both of those options selected (i.e., "Upload covers for books" and "Always upload covers"). Yet, I still get distorted cover images on the Home Screen if I have my margins set to anything but zero.

Anything else I can try?
Could you convert a copy of the ePub I sent you that would have this working, just so I can make sure it's an issue with my Calibre settings and not the Kobo itself?

[davidfor]

I has just occurred to me that you might be using an micro SD card. Are you putting the book on an SD card? If so, there isn't anything we can do. The current firmware generates the cover image each time it needs it.

[theboyk]

Nope, straight to main memory.

[davidfor]

No SD card, so I need to type.

Originally Posted by theboyk

I'm on the latest version of Calibre, and I'm running the latest available version of Kobo firmware. And I have both of those options selected (i.e., "Upload covers for books" and "Always upload covers"). Yet, I still get distorted cover images on the Home Screen if I have my margins set to anything but zero.

Anything else I can try?

When the device is connected, open ".kobo\images" on the device. This has all the cover images. Find the covers for the book. If you are using the calibre default save template, the names will look like:

file____mnt_onboard_Corey,_James_S_A__Leviathan_Wa kes_-_James_S_A__Corey_epub - N3_FULL.parsed.parsed
file____mnt_onboard_Corey,_James_S_A__Leviathan_Wa kes_-_James_S_A__Corey_epub - N3_LIBRARY_FULL.parsed
file____mnt_onboard_Corey,_James_S_A__Leviathan_Wa kes_-_James_S_A__Corey_epub - N3_LIBRARY_GRID.parsed

The exact name will depend on the save template you use, but it probably includes the book title. Doing a search for "Leviathan" should find them. If the "N3_LIBRARY_FULL" is not there, that is OK.

The files are just JPEGs with a different extension. You should be able to open then with an image viewer. If not, changing the extension to "JPG" will solve that. When you open them, you can check if they are correctly proportioned. Also, check the size. They should be:
- N3_LIBRARY_FULL - 355*473 - This is used for the Details screen
- N3_FULL - 600*800 - This is used for the Home screen and screensaver
- N3_LIBRARY_GRID - 149*198 - This is used for the library lists.

Also check the timestamps of the files. If calibre created them, the timestamps should be roughly when you sent them over. If the device created them, the timestamps will be whenever it needed to create them but will be in GMT rather than the local timezone.

The last thing we can do is a debug log. That will show me what the driver is doing. I'll send the instructions in a PM.

Could you convert a copy of the ePub I sent you that would have this working, just so I can make sure it's an issue with my Calibre settings and not the Kobo itself?

I'll PM a link.