In my experience that's more of a side effect from TFT displays. Each pixel has its own gate and can hold a charge for quite a long time. It can also be a side

In my experience that's more of a side effect from TFT displays. Each pixel has its own gate and can hold a charge for quite a long time. It can also be a side effect of older LCDs, when power is lost the crystal can take a long amount of time to depolarize. If you apply backlight you'll see an afterimage. LCDs are driven by the controller and have no knowledge of the framebuffer location, or even access to the host address and data busses. So if you see an afterimage, that's in the pixel.