How to view .HEIC photos from iPhone IOS 11+ on Ubuntu?

Friends send me email with attachments containing .HEIC pictures from their iPhone. How can I easily view these pictures on Ubuntu?

HEIC is the file format name Apple has chosen for the new HEIF (High Efficiency Image Format) Standard. Using advanced and modern compression methods, it allows photos to be created in smaller file sizes while retaining a higher image quality compared to JPEG/JPG.

Every iOS update comes with a host of changes, but some are not immediately obvious. ... HEIC will be used by default on new photos on iOS 11, and it's designed to save you storage space. As it's a new container format, there will be some incompatibilities along the way, and Apple does a good job at handling most of these.

To view these .HEIC images on Ubuntu, do this...

sudo apt update
sudo apt install heif-gdk-pixbuf
sudo apt install heif-thumbnailer
sudo apt install libheif1:amd64

Then save one of the .HEIC images to your ~/Pictures folder, right-click on the image icon, select Properties, and set the default application to Open With as Image Viewer.

Now a double-click on the image icon will open the file in Image Viewer for viewing.

Image thumbnails will also be seen in Files (Nautilus) windows.

In Thunderbird you can now also view these images in the original email attachment bar.