Lesson in Ghost hunting
I took this photo from a popular site to prove a point - suggestive optical illusions: pareidolia. The mind is a powerful tool; if you think you see something, you WILL see it. So, in future, when you suggest to yourself you can see a face in the wooden door, or a stone wall/ flooring you will see it, and others too if you look closely. I will remind those out there who suffer from this to look again, and see the grains in the wood, the water stains on that wall. Not all is what it appears to be. A true ghost capture is one you cannot explain by science or simple reasoning indefinitely.