>Psychtoolbox>PsychTests

ResolutionTest prints screen resolutions reported by Screen ‘Resolution’
and ‘Resolutions’.

Usage: ResolutionTest([screenNumbers=all]);

On Linux, if a Psychtoolbox screen (=X-Screen) has multiple video outputs
attached, this function will report both, per output settings and modes and
the unified resolution of a screen - consisting of virtual resolutions and
settings formed by all attached outputs. Per-Output settings on Linux can
be made via Screen(‘ConfigureDisplay’, ‘Scanout’, screenNumber, outputNumber, …);
Screen(‘Resolution’, screenNumber, …); only affects or reports the unified
“virtual resolution” of a whole X-Screen, not of its individual outputs.

Also see SetResolution, NearestResolution, and Screen Resolution and Resolutions.