For biometric authentication, there are several anti-spoofing techniques. From the simplest ones, like eye blink detection, measuring intrinsic facial movement (after all, a photo can’t blink … although a decontextualized video might also work), to the latest texture analysis techniques attached to Challenges to the user such as looking for pupil dilation, causing the screen to go dark and then suddenly shine.
Be careful, however, with the processes that generate friction, causing possible conversion falls. More sophisticated techniques use 3D cameras to search depth information on a 3D face, or infrared cameras to detect thermal information. However, both require special equipment, and therefore are not compatible with most web cameras and mobile phone cameras available today.