Apple - How to convert a HEIF/HEIC image to JPEG in El Capitan?

You can use the command line tool imagemagick to convert HEIC images to JPG.

# install imagemagick
brew install imagemagick

# convert a single image
magick convert foo.HEIC foo.jpg

# bulk convert multiple images
magick mogrify -monitor -format jpg *.HEIC

We just released this little free app for macOS: https://imazing.com/heic

Minimum macOS version is 10.8, so no worries with El Capitan. : )

I found Dropbox to be a good conversion tool, as it does it transparently for the usage on any operating system and platform.

When you do the shot from iPhone, Dropbox automatically converts .heic image to .jpg when uploading it to computer (controlled by the settings). Since I'm using both Windows OS and MacOS, there's no need to install separate additional applications.