Face & Ectoplasm Ghost Picture

Mandy Leonard sent us this ghost picture of ectoplasm and somehow a man's face seems almost pasted into the background of this photo...we are stymied as to how this could have happened? Take a look:

"I was taking this picture of my son in my living room as he was playing. When I downloaded it to my computer, I noticed the image. First, I only noticed the smoke-like figure of legs standing above him. But as I looked closer, in the background behind his father, I saw a face. A face of someone who does not live here. We were home alone when I took the picture so it couldn't be confused with someone else that was here. I have no mirrors in the area of where the picture was taken. Can you please explain this mysterious figure and face in the picture with my son? If so, would you please let me know what it is?"