Can older iPhones (with iOS 11) display HEIF images? Consider the scenario of restoring a backup taken on an HEIF/HEVC capable device (e.g. the iPhone 7 or newer) to an older device (e.g. an iPhone 6s, running iOS 11).

Will images and videos taken on the new device and accessed on the old one be:


Not restored at all?
Restored, but not displayable (i.e. taking up space, accessible for sharing/uploading etc., but not shown in the gallery)?
Be fully compatible, and displayed/decoded in software?


Is there a difference between images and videos? (I could imagine that images are decoded in software on older devices, for example.)
There wouldn't be a problem with that. The older iPhone would be able to convert the image back to a readable format.

More info here.

Edit: This will be an issue if trying to view the videos on a mid-2014 MacBook Pro or older. There is ways around it, but only the 2015+ editions can automatically convert them.
I have recently found this out while trying to view videos from my iPhone 8 on my mid-2014 MBP.