What’s the difference between median and mean while stacking?
Say you stack five images of the exact same scene: a tan pedestrian plaza with a woman in a red dress walking through. In four of your shots the woman is out of the frame, but in the 5th shot she’s right in the middle of the photo. The Median stack mode looks for the pixels which are most common to all of the photos and uses those in the final image. So in this case the final stacked image wouldn’t show the image at all, because the most common pixels are the tan of the plaza when she’s not in the frame. The Mean stack mode does an average of all the pixels of all the photos, so in the final stacked image you would see a ghostly image of the woman in red, because the pixels would be 1/5 red and 4/5 tan. The best way to see this is to create some sample images for yourself and play with the different modes.