I have a friend who is an amateur photographer. She has an Imac. I suggested she calibrate her monitor, but don't know anything about Mac. Looking for a low cost ($200) solution for her system:
macOS10.13.2
IMac (Retina 5K, 27 inch, Mid 2015)
Processor 3.3 GHz IntelCore i5
Memory 8 GB 1600 MHz DDR3
Startup discMacintosh
HDGraphics AMDRadeon R9 M290 2 GB
Suggestions?