Book Cover Aspect Ratio Mystery

[MartyTX]

As usual, I was not the first in line to upgrade my software and did all of the following last week:

iOS 7.1 to 9.0.2
iTunes 11.1 to 12.1.3
Marvin 2.7.5 to to 2.8.5

The advantage of doing all the changes at once: all my fussing and fuming was confined to only one week.
The now obvious disadvantage: I really don't have a clue which update(s) did what!

My current mystery:
After I bought my iPad Mini a couple of years ago, part of my book fine-tuning in calibre is to resize all book covers to 400x600 pixels. This size worked fine in Marvin on my iPad Mini; all covers nicely filled one page and looked very good.

After the version updates, the very same books that used to look good now spill over onto a second page. They are too tall for one page!

I now have to resize covers to 450x600 pixels ... and all is good again! I'm doing the resizing and reloading into Marvin when I decide which book I'll be reading next. It's not worth the effort to do all books at once, since the cover issue does not effect reading the book.

Just curious if the change was caused by Marvin, iOS or a combination of the two.
- Has anyone seen the "Book Cover Aspect Ratio Mystery" on an iPad Mini (or full size iPad)?
- Any clue why increasing the cover width to 450 makes the cover fit fine?

[eschwartz]

I don't know about Marvin or iOS, but perhaps the new version can't handle covers as high as the old one could.
Although I would think it should first fit the height to the page, and then calculate the needed width.


Increasing the width means the height is now smaller in comparison -- when using cover aspect ratio, you can also think of the new cover as 400*533 pixels.
Less pixels to squeeze out the bottom and onto the next page.

[MartyTX]

Yes, aspect ratio is the key, not the actual pixel size:

600:450 = 1.33:1
533:400 = 1.33:1
900:675 = 1.33:1

I experimented and all the above cover sizes are a nice fit for Marvin. Even the jumbo 900:675 cover fits the same way as the smaller covers. For some reason, 600:400 = 1.5 has fallen out of favor with Marvin and/or iOS-9.

So, the value of this revelation ... and $2.00 ... will buy us a lukewarm cup of coffee!

Have a nice day.

[Turtle91]

You could always try an SVG wrapper...then it doesn't matter what size cover image you use!

[JSWolf]

You are making your covers not properly aspect ratio correct. Stick with the original resolution and you can see the cover on screen as it was meant to be seen.

Besides, if you do as Turtle91 suggested, you can easily go full screen (off-aspect) or full screen (correct aspect) without having to resize at all.

[MartyTX]

Turtle91, JSWolf,

Thanks for the svg suggestion. By changing to: viewBox="0 0 450 600" covers fit on one screen in their original aspect ratio.

"Give an inch and I'll ask for a mile ..."

Is there a way to set a default size for the viewbox so I don't have to change to "0 0 450 600" in each ePub? Possibly set a default in a style.css setting?

This novice is definitely venturing into water above his head ...

[eschwartz]

calibre and Sigil both have the ability to regenerate the Cover page, and will wrap the cover image in an SVG. As you have seen, there is a good reason for that.

The SVG wrapper should declare the true size of the image, and it will be scaled appropriately. That's how both calibre and Sigil generate them.


If you are adding SVG wrappers, you can do it all right then and there.




calibre's Modify EPUB plugin should allow you to recreate the cover (using proper SVG wrappers) in all your EPUBs in bulk -- without changing anything else, like conversions would do.

[MartyTX]

Originally Posted by eschwartz

calibre's Modify EPUB plugin should allow you to recreate the cover (using proper SVG wrappers) in all your EPUBs in bulk -- without changing anything else, like conversions would do.

Because you don't have an iPad, you are missing out on all the absolute fun that goes along with iOS updates, iTunes updates, and Marvin updates.

Modify ePub, Resize Cover, and SVG Wrappers are working fine like they always have. Unfortunately, as I originally posted, covers that used to fit no longer fit because of updates to Marvin and/or iOS. The ePubs themselves have not been changed. However, I now have to manually tweak the SVG for existing books because of Marvin/iOS changes.

It's not too late for you to buy an iPad and start having the fun you've been missing!

[Turtle91]

Originally Posted by MartyTX

Turtle91, JSWolf,

Thanks for the svg suggestion. By changing to: viewBox="0 0 450 600" covers fit on one screen in their original aspect ratio.

"Give an inch and I'll ask for a mile ..."

Is there a way to set a default size for the viewbox so I don't have to change to "0 0 450 600" in each ePub? Possibly set a default in a style.css setting?

This novice is definitely venturing into water above his head ...

You can save a template file in Sigil's directory called "cover.html" and it will use that when you press tools/add cover. (Try looking in this directory for windows: ...AppData\Local\sigil-ebook\sigil) You can design the template any way you wish, including the variables SGC_IMAGE_FILENAME, SGC_IMAGE_WIDTH and SGC_IMAGE_HEIGHT, but I use the following:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"><html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>Cover</title>
</head>

<body style="margin:0; padding:0; text-align:center; background-color:black">
  <h1 style="display:none" title="Cover"/>

  <div style="margin:0; padding:0; text-align:center">
    <svg xmlns="http://www.w3.org/2000/svg" height="100%" preserveAspectRatio="xMidYMid meet" version="1.1" viewBox="0 0 SGC_IMAGE_WIDTH SGC_IMAGE_HEIGHT" width="100%" xmlns:xlink="http://www.w3.org/1999/xlink">
      <image height="SGC_IMAGE_HEIGHT" width="SGC_IMAGE_WIDTH" xlink:href="SGC_IMAGE_FILENAME"/>
    </svg>
  </div>
</body>
</html>

Cheers!

[eschwartz]

Originally Posted by MartyTX

Because you don't have an iPad, you are missing out on all the absolute fun that goes along with iOS updates, iTunes updates, and Marvin updates.

Modify ePub, Resize Cover, and SVG Wrappers are working fine like they always have. Unfortunately, as I originally posted, covers that used to fit no longer fit because of updates to Marvin and/or iOS. The ePubs themselves have not been changed. However, I now have to manually tweak the SVG for existing books because of Marvin/iOS changes.

So a perfectly reasonable, working SVG wrapper still doesn't work -- unless it tells Marvin that the natural size is 450x600?
Curiouser and curiouser...

It's not too late for you to buy an iPad and start having the fun you've been missing!

I'll pass.

[Turtle91]

I've been using Marvin since the beginning...always with SVG wrapped covers...none of them are as small as 450x600 and I've never had a problem with them.

[MartyTX]

Turtle91,

What version of iOS and Marvin are you running? I'm on 9.0.2 and 2.8.5 running on 1st generation (non-retina) iPad Mini.

In the scheme of things, tweaking a cover is a very minor chore. However, I'm thinking about rollingback to Marvin 2.7.5 just to see if that solves my "cover conundrum". But if you are on 2.8.5 and are problem free, I don't think a rollback would solve anything.

It's been summertime in Amarillo the past week ... high 80's to low 90's. Same with Altus?

[Turtle91]

2.8.5 and 9.02...running on everything from iPhone 4s-6 and iPad mini-Air.

[MartyTX]

Thanks for the info. Looks like a Marvin rollback wouldn't accomplish anything.

I still have to use a ViewBox with "0 0 450 600" to get the covers I want. However, the Sigil template info you sent makes changing the ViewBox a two-click process: Tools > Add cover.

I had to name the template cover.Xhtml for it to work.

Mystery isn't solved, but I think I can "click twice" and be happy with that!

Thanks and have a good one!

[Turtle91]

No worries! Although, the way I understand it, it doesn't matter the size of the image. As long as you have the viewport the same then the preserveAspectRatio="xMidYMid meet" command should center the image on the screen and the height/width 100% should fill any available space while maintaining the original aspect ratio.

I already talked with Kris about a bug on the placement of the image...instead of centering the image on the screen it always places it at the top...perhaps yours is a related issue?? If so, hopefully it gets fixed when he releases the next update.

You are exactly correct .xhtml...sorry!