Hi, to build gmic with homebrew and display:
Install XQuartz
edit the gmic formula and enable_X=ON
make a link: ln -s /opt/X11/include/X11 /usr/local/include/X11
Install gmic with brew install gmic —with-ffmpeg --with-libtiff --with-openexr
By the way, I think the formula is not ready, there is no possibility to build the plugin nor works the git build (—HEAD)