I have seen many examples of using the median of a stack in Photoshop to remove variable foreground elements like tourists in vacation photos. (https://photoshoptrainingchannel.com/remove-tourists-stack-mode/)
I am wondering if there is a way to do the opposite in photoshop or another tool? In the tourist example this would mean keeping all of the variable elements (the people moving in the stack) but removing the median background (the buildings and scenery).
It wouldn't work, you would just get noise. See the median filter works because the background is relatively static over many pictures. But the crowd is not static so you would get one pixel of a car adjoined by one pixel of a lady. In other words noise.
However, you can use median to isolate the background then take the crowd of one picture and do a difference key. Though difference keying is a bit of a poor mans solution in general. Doing both median and difference keying works as well, or sometimes even better than, as finding a empty background and using that as the difference source.
