I have no references to back this up, but I did have some odd results with setting my Huawei P9's camera to "aperture mode" (this was a while back, the actual mode's name might have been different). Essentially what you'd expect is that the subject should be crisp, but anything further away or closer should blur significantly.
I assumed that this was done as expected, via the lens. But certain scenes would have this "effect" applied wrong; things that should have been out of focus in the background were in focus, while simultaneously things at the same distance were blurred elsewhere, and so on.
I quickly became convinced it was a software effect, and the algorithm was simply guessing the depth wrong. While it looked great most of the time, it only took a few of these oddball Escher-esque photos to put me off it for good (since you generally only notice it afterwards, when it's too late to retake).
EDIT: Actually, having now gone through this article, it has some really good examples of how this can go wrong (e.g. dog with "crown" instead of background tree), and how odd it can feel.
I assumed that this was done as expected, via the lens. But certain scenes would have this "effect" applied wrong; things that should have been out of focus in the background were in focus, while simultaneously things at the same distance were blurred elsewhere, and so on.
I quickly became convinced it was a software effect, and the algorithm was simply guessing the depth wrong. While it looked great most of the time, it only took a few of these oddball Escher-esque photos to put me off it for good (since you generally only notice it afterwards, when it's too late to retake).
EDIT: Actually, having now gone through this article, it has some really good examples of how this can go wrong (e.g. dog with "crown" instead of background tree), and how odd it can feel.