One of the major problems encountered with LCD monitors is the “dead pixels”: all of a sudden we start to see white or black dots that remain visible regardless of what we are displaying.
Fortunately this kind problem is covered by any major monitor warranty and if we start to notice those dead pixels in time before the warranty is over, we can ask for a RMA. But there is one catch before we can send the monitor to the manufacturer: are we sure that those apparently dead pixels are indeed hardware-ly dead and it is not just a bug in the graphics card drivers or in the operating system itself?
If we use Linux as operative system, one tool we can use to check for dead pixels is LCD Nurse.
The main feature of LCD Nurse is to test if those pixels are indeed dead or if it is a problems with graphics card or operating system.
To find one or more dead pixels LCD Nurse creates various screenshots of different colors, such as blue, green, etc, to emphasis dots of wrong colors (such as white, red, etc.); once a dead pixel is identified, LCD Nurse will launch some tools to try to solve the problem. If the problem is in the graphics card or the operating system, LCD Nurse has different tools to correct them.
LCD Nurse is available for Ubuntu, Debian and derived distributions. You can download the deb package from the LCD Nurse official website.