The problem
Beauty filters remove pores and fine skin texture, slim the jaw, narrow the nose, enlarge the eyes and lift the brows. Vision models judge geometry reasonably but frequently rate heavily smoothed skin as natural.
The measurement
TrueFace computes the ratio of fine detail (luma minus a σ = 1.5 Gaussian blur) inside the face to a ring around it in the same photo. A ratio below 0.42 means the skin is smoother than its surroundings, and a “natural” verdict becomes Uncertain with that reason shown.
Reshaping check
Each scan also rates warping per region — jaw, nose, eyes, brows. Those tags decide which geometric changes a reconstruction is allowed to reverse.
Limits
Heavy compression or noise reduction lowers the ratio on natural photos, so it never flags a filter by itself. The cutoff is provisional and based on few reference pairs.
Full method: technical whitepaper.