Accessing Advanced Color Calibration Options in OS X El Capitan Using a Shortcut
If you spend a lot of time tweaking your display, you might have noticed that El Capitan seems to get rid of advanced options, including customizing your own and target gamma. Fortunately, these settings are just hidden behind the keyboard shortcut.
To revert to advanced settings, go to System Preferences> Display, select the Color tab, then hold down the Option key and click Calibrate. This will cause the “Expert Mode” checkbox to appear in the Display Calibrator Assistant. From there, you will calibrate as always.
Accessing the Expert Mode Screen Color Calibrator in OS X El Capitan | OS X Daily