After installation, you can check the setup following this check guide.

Requirements

Install CMake (https://www.cmake.org/download/)
Install XCode tools. Launch in a terminal:
xcode-select --install
Install Qt 5.12 or later (https://www.qt.io/download-qt-installer) (do not install Qt 6.XX). You must create a Qt account, then install the following components:
You need to enter the following lines in a terminal to get around a bug regarding running a debug program:

source /Library/Frameworks/Imagine.Framework/Versions/Current/Resources/doc/html/fixQtDebug.sh

If it does not exist, download the file fixQtDebug.sh, and run in terminal:

source $HOME/Downloads/fixQtDebug.sh

If some error message appears, your installation is not standard:

find . -name Qt5CoreConfig.cmake

cat $HOME/Downloads/fixQtDebug.sh

Replace the first three cd commands with the full path (up to, and not including, clang_64), for instance:

cd /Users/pascal/Qt/5.12.1

run the subsequent commands of the script by copy-pasting them in the terminal.

Install package

Use the installer (which installs in folder /Library/Frameworks) or extract the archive package:

Warning for MacOS Mojave users (MacOS 10.14), and probably Catalina (10.15) : OpenGL support is depecrecated by Apple, install the following archive instead if you have trouble when compiling. You will have no 3D support and maybe a warning with Cmake, but it should proceed with no problem.

Go to Usage and check the tests.

Note: users of older versions needed the infamous IMAGINEPP_ROOT environment variable, which is no longer necessary. However, if you did not install in the expected location (/Library/Frameworks), you must indicate the path with the Imagine_DIR environment variable.

Alternative: compiling from source

Follow the same procedure as for Linux:

Build

after downloading and extracting the source package:

http://imagine.enpc.fr/~monasse/Imagine++/downloads/Imagine++-5.0.0-Source.tar.gz

After that, to create an installer package (Imagine.pkg), you can run the command

source <ImageSrcDir>/CMake/mkFramework.sh Imagine++-5.0.0-Darwin-x86_64.tar.gz

Uninstallation

sudo rm -rf /Library/Frameworks/Imagine.framework