Color Patches on monitor screen corners can be eliminated by "Degaussing" the monitor by pressing the Power Switch Off and the ON again. Most monitors� has a "auto-degaussing" function during Power OFF of the monitor. LG Monitors have the Degaussing Option on the Menu Option Screen. These Color patches appear due to the changes in the magnetic fields inside the monitor when the monitor is tilted, or swirled in direction.
To degauss is to demagnetize. Degaussing a computer display removes any undesirable magnetic field that may have built up within the display, causing distortion of the image or color. Display monitors with cathode ray tube (CRT) technology are subject to the buildup of magnetic fields.
Removing color patches on monitor screen (Degaussing)
Look at the devices installed in the vicinity of your PC's monitor. Large stereo speakers (or even some of the multimedia speakers used on PC systems), televisions, motor-driven tools or appliances, and even faulty fluorescent light assemblies can cause interference resulting in a problem display, such as screen flickering. Move the PC or the offending devices elsewhere, then evaluate to see if the flickering diminishes or stops altogether.