Have you noticed that the footprints appear embossed as though they are rising up above the beach. This is an optical illusion caused by how our brain functions. When this photograph was made, the camera was pointing straight down at the ground. When you view it on the computer monitor, the orientation has changed. You look at pictures knowing that sunlight comes from above, so shadows should appear on the bottom of objects. By flipping this photo 180 degrees, the foot prints now look correct.

Same effect can be acchived if you look at this picture below. Notice how you automatically asume some buttons are embossed and some aren’t?