How to detect a screen in a photo Is there a way to make a difference between a photo of an actual object and a photo of an object through a computer or smartphone screen.

For example: how can I detect that the second image is taken from a screen?




Thank you very much!
The first things I would try is to see if smartphone pixels are visible (if the photo is high res) or if strange aliasing occurs (your example image shows both). 

Another classical test (but not adapted to any scenes) is to detect perspective bias: if the camera is not exactly parallel to the smartphone screen, then 3D objects projected on the image on screen are projected again to the camera captor through a slightly different perspective. If the scene contains spheres, discs (physical or as reflects, for instance), perpendicular angles, or any similar invariant, then you can detect this.   (this kind of trick is also used to detect images photoshoped by composition of several images).