HEIF

Mac OS X 10.13.4+: Convert any image to HEIF/HEIC format

Usage: HEIF [-q=quality] <image> where quality is in range from 0.1 (max compression) to 1.0 (lossless), default is 0.76

Compiling on macOS (to create executable HEIF and copying to bin folder):

cd HEIF
swiftc -O -o HEIF main.swift
cp HEIF /usr/local/bin

Or simply run from terminal without compilation:

./main.swift <image1> [optional image2] [optional image3] [...]

Please note: odd image dimensions will be truncated by Apple's codec to even ones.

Swift 5 runtime

Starting with Xcode 10.2, Swift 5 command line programs you build require the Swift 5 runtime support libraries built into macOS. These libraries are included in the OS starting with macOS Mojave 10.14.4. When running on earlier versions of macOS, this package must be installed to provide the necessary Swift 5 libraries.