Apologies for the poor explanation, I'm a Pentax guy so not very familiar with Nikon gear, and have been asked if there is any way to fix this problem.
My MIL has a Nikon D7200 which has had the "Image Area" option set wrong (to 1.3x) in the menu for quite a while (the camera is new to her as well). This has meant that the viewfinder has been showing a much larger area than is captured, and many shots have missed edges.
As I understand it, the image area affects the amount of the sensor which is used? Is that correct? It has two options "DX" and "1.3x" so I assume it's a way to choose the crop of the sensor.
The photos were taken as RAW (NEF), and the RAW images suggest that the pixel count is the same between images with/without the image area set to 1.3x. Is this fixable in post processing? Or are the photo subjects permanently decapitated?