My iMac Screen has changed its color on some parts of the screen(Like in the corner and the middle).. The whole brightness is gone and is dull on the affected area.Please help me what should i do to rectify it.Thank you..
LCD panels, on occasion fail with this sort of fault, the screen is drive in an array, vertical and horizontal strips, when the controller (built into the panel) fails, patches of colour (normally solid), vertical or horizontal strips etc appear in the screen.
If your machine is in warranty (or you have applecare) CALL THEM NOW !
Your screen has probably been influenced by a magnetic field, like a speaker or something. You need to degauss it... the screen has no direct degauss option/button, but I think its possible somehow.
Someone else here should know what to do exactly.