Cover Images in EPUB3

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I'm a first-time poster, long-time lurker. In anticipation of better adoption of the EPUB3 standard by the big eBook stores, we're trying to get our arms around the new specification. I would like to inquire specifically about embedding the cover image in the EPUB package. Please excuse me if this question has been answered elsewhere.

The EPUB 3 spec states that the cover image should be declared in the Manifest Section of the Package Document. Here is the example XML that is provided from the IDPF:

<item properties="cover-image" id="ci" href="cover.svg" media-type="image/svg+xml" />

However, Amazon, Barnes & Noble, and iBookstore currently require a declaration in the Metadata Section as well for cover images. We use the following meta element in our OPF file that is suggested by the vendors:

<meta name="cover" content="My_Cover_ID" />

And the corresponding item element in the Manifest Section:

<item href="cover.jpg" id="My_Cover_ID" media-type="image/jpeg" />

Looking at the new EPUB 3 spec, this meta element would be invalid in the Metadata Section since it does not have a "property" attribute.

For anyone working on the new EPUB 3 reading systems, I would like to inquire how the issue of backward comparability will be addressed to ensure that cover images are properly rendered and recognized as the unique cover image. Should we continue adding this meta element in the Metadata Section even though it is a violation of the EPUB 3 spec? Will readers with EPUB 2 type reading systems be able to see the cover image if only the new EPUB 3 item element is included in the Manifest Section? Any guidance on best practices?

Thank you very much for your time.

The working group did endeavour to make the specification forwards compatible with EPUB 2, and although EPUB 3 implements a new metadata model you can still include the older EPUB 2 meta element exactly for cases like you've encountered.

The element is marked obsolete as EPUB 3 reading systems are not expected to process them anymore, but it's not invalid to include the elements in the package metadata to facilitate this kind of discovery.

Hope this helps.

Thank you, Matt. This is very helpful. We will continue to include this meta element in the Metadata Section to ensure compatibility with eReading devices that can only support EPUB 2.

And thank you for pointing this out! I've added a note to the thread on cross-compatibility with EPUB 2 to include cover metadata, as we were missing it.

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