This post starts off topic, but does get back on topic in the end. Please bear with me.
I assume the readers of this blog know what the classic Turing test [Wikipedia] is. To pass the Turing test a machine must be able to impersonate human responses to such a degree that a human can't distinguish between the machine and a human based on their responses.
The original Turing test is meant to test artificial intelligence. Similar tests could be used to test other artificial entities - such as video.
A Video Turing test (TM) could be defined as follows. Set up a wall with a window and with a video monitor that displays a stream captured by a camera on the other side of the wall.To pass the Video Turing test (VTT), it needs to be impossible for a human to distinguish the window from the monitor.
There are various levels of VTTs. A 2D VTT assumes a static one-eyed viewer. A 3D VTT would also work with a two-eyed viewer, but still static. A virtual reality VTT would also work with a moving viewer.
The concept of Reverse Turing test has been used for a Turing test in which a computer is the judge - i.e. to pass the Reverse Turing test a machine must be able to impersonate human
responses to such a degree that a computer can't distinguish between the machine and a human based on their responses. It's not clear how interesting such a test is, since one would assume that if a computer is able to distinguish between a machine and a human the same computer would also be able to generate a response that it itself couldn't distinguish from a human's (and thus pass the Reverse Turing test).
Which brings us to the Reverse Video Turing test (or RVTT). An RVTT is interesting because it is clearly easier to identify bad video that to generate good video (for example, I myself am able to identify bad video but I can't generate any video at all). Just like VTTs, RVTTs can be 2D, 3D or VR.
The concept of an RVTT finally brings us back on topic. A few months ago I wrote about an Android feature that uses face recognition to authenticate the device owner. A Malaysian blogger showed that it's trivial to circumvent this mechanism by using a photo of the device owner.
As long as screens can pass RVTTs, face recognition will not be a reliable method for authentication. But, as I explained in that post, even if a simple 2D screen may be able to pass a 2D RVTT, there's no way it can pass a 3D or VR RVTT - which is what one needs to do if one wants strong authentication based on face recognition.