Its very strange to me .. I tried to recognize the problem by checking all datasheets information and search for same situation in the net, but unfortunately I find nothing .. please help me.
the base issue is when i render some thing in TFT lcd and don't change it for a while ( minutes or hours ) and then change it to dark, a light shadow of last image can be seen on the place. it was very surprising to me because as I know this issue was for old CRT displays and not for LCDs and I'd never seen any same problem with my other TFT based LCD projects. so is it true pixels of a LCD could become spoiled because of no changing awhile, or there is other problem that I cant see!!.
an other point is the shadow is faded out and cleared by passing time ( about 10 minutes ) but NOT by reset or power off !!!