First of all, let's get some basic neuroscience and psychology out of the way. We don't "see" things, we perceive them. Our eyes are rather imperfect organs with which we receive visual information. The actual seeing is done in the visual cortex, contained in the parietal lobe of the brain, although appropriate investigation also shows that other parts of the brain are involved.
At the fairly mechanistic level of visual perception it can be shown that, in the eye itself, only a small percentage of the visual field is "in colour" only a very small area is "sharp", that there is an area with no visual sensors at all, the "blind spot" and that visual information falling the left side of the retina is sent to the right-hand side of the brain (and vice versa). What we perceive as reality is actually an elaborate construction based on visual information, memory and expectation.
Perception is not veridical. it can allow for all sorts of subjective influences to condition what we think is real. Another perceptual phenomenon is music. Musical instruments do not produce music - they produce a toot, or a whistle or a plunk or a boom. Our brains reassemble those sounds into the physical and emotional experience we call music. If you want an interesting example of this, at the start of the last movement of Tchaikovsky's 6th Symphony, the first and second violins are each playing their parts from the score but you hear neither - you hear a melody which nobody is playing.
To get onto digital photography. The advent of digital photography has produced the situation where almost anyone can produce elaborate fakes. A few years ago the film Gravity won numerous awards. But few people watching the film were aware that most of what they were seeing was produced in the computers of a company called Framestore, in central London. About 90% of the film was the result of digital processes. The software to manipulate digital photographs - both still and moving - is readily available, in some cases simply by downloading from the internet.
The "spirit" image in the clip which Sriram finds so convincing can be much more readily accepted as fake than real by people with open minds.
