The Telltale Flicker: How Light Patterns Expose AI-Generated Fake Videos

Light doesn’t lie. When artificial intelligence tries to fake reality, it stumbles over physics in ways that would make Newton weep. The most sophisticated deepfake algorithms still can’t nail how light actually works, and that’s their Achilles’ heel.

Watch someone’s face in an AI-generated video closely. Really closely. The shadows under their nose might suggest light coming from the left, but their forehead gleams like it’s lit from above. Their cheeks catch highlights that belong in a different universe entirely. It’s amateur hour, except the amateurs are multibillion-dollar AI models that somehow forgot basic geometry.

The temporal stuff gets weirder. Frame by frame, these videos flicker like broken Christmas lights. One second the person’s skin has warm tones, the next it’s gone cold. Shadows breathe in and out like they’re alive. Specular highlights on jewelry jump around like caffeinated fleas. Real cameras don’t do this. Real light sources don’t suddenly change their minds about physics between frames. Look for unnatural blinking patterns too—AI struggles to replicate the natural rhythm and frequency of human eye movements.

Then there’s the comedy of errors in reflection logic. Eyes are supposed to reflect what’s in front of them, but AI-generated eyes often show catchlights from phantom windows that don’t exist. Glasses become portals to alternate dimensions, reflecting rooms that aren’t there. Metal surfaces blur in ways that would require the laws of optics to take a vacation.

The bigger picture reveals even more amateur mistakes. Background lighting goes one way, foreground another, like they’re in different solar systems. Fog doesn’t wrap around bodies properly. Volumetric light rays pass through people like they’re ghosts. The inverse-square law might as well not exist. Watch for color temperatures that clash between different parts of the scene—warm tungsten lighting on the face while cool daylight bathes the background.

Contact shadows are particularly damning evidence. Feet float mysteriously above ground. Objects hover without darkening the surface beneath them. Multiple light sources create shadow patterns that would require non-Euclidean geometry to explain.

These aren’t subtle tells requiring forensic analysis. They’re glaring errors that betray the synthetic nature of the content. As AI gets better at faces and bodies, light remains the stubborn truth-teller, exposing the fake through simple physics that algorithms still can’t master.