Found myself in the situation where the photos from my iPhone X when copied over are all in HEIC format – first time I have taken images off the phone, as such first time I have seen this. Found some applications available for Windows – but it looked super dodgy when I installed it, so removed it and thought this could be done using Linux and possibly even via Windows Subsystem for Linux (WSL). Sure enough it could be and was super easy……
Install a Debian WSL image from the Microsoft Store.
From within your Debian system perform the following steps so we can install the required packages that contains what we need.
$ sudo apt-get update
$ sudo apt-get install libheif-examples
Now we can use heif-convert to convert our HEIC images into jpeg (jpg).
I’d placed my HEI images into C:\temp on my Windows host, so I could perform the conversion using the steps below for a single image
$ cd /mnt/c/temp
$ heif-convert IMG_0100.HEIC IMG_0100.jpg
Now the IMG_0100.jpg file produced can be opened in Windows using Paint and other utilities as expected. The original file can be subsequently removed, as its no longer required – as conversion is completed.
Source: Stuff Jason Does