How to convert heic to jpg

[Fergus Daly]

Ages ago there was a thread about what package(s) to install in order to be able to
$ convert img001.heic img002.jpg
but I cannot now find it. Can anybody help? 
Note 1 Under Package Search "heic" I found ImageMagick; but I have that already, to no effect.
Note 2 One used to be able to enter "site:cygwin.com heic" (or similar) in the Google search bar
to search Mail Archives but now that seems to provide incomplete responses. Is there a variation
on this that provides an exhaustive search of the archives?