Optical Physics of Composite Images
When a fraudster cuts a person or object from one photo and pastes them into another, matching the exact angle, color temperature, and diffuse falloff of the target scene’s light source is virtually impossible.
By computing 2D luminance vectors and mapping directional surface normals to a color wheel, mismatched lighting angles immediately display conflicting color hues.
If one person is lit from 45 degrees north-west and an adjacent subject is lit from 30 degrees north-east, the image is a confirmed composite.