Please read the available documentation about the G’MIC scripting language, starting from here :
http://gmic.eu/tutorial/basics.shtml
All is explained better there that I could do here with a few words 
Please read the available documentation about the G’MIC scripting language, starting from here :
http://gmic.eu/tutorial/basics.shtml
All is explained better there that I could do here with a few words 