how install screentest ubuntu

ubuntu

screentest

Utility to test the quality of screens
http://screentest.sourceforge.net/
Install sudo apt install screentest
Description:

Screentest is a CRT and LCD screen testing utility. Ever wondered how good the quality (sharpness, linearity, convergence, etc.) of your CRT/LCD monitor is? Screentest displays the testing patterns which you can use to evaluate the quality of your monitor.