False defects: the real production killer

Finding defects is easy. Finding only real defects is hard.

Busy surface texture that triggers false calls — Surface texture, dust and lighting changes all look like defects to an over-eager algorithm.

Common causes of false calls

Dust
Lighting changes
Surface texture
Process variation
Focus variation

Why it matters

Many projects spend more effort reducing false calls than they ever spent finding actual defects. A system that cries wolf gets switched off by operators, which is the worst possible outcome: now you have an expensive system and zero coverage.

A system nobody trusts is worse than no system at all.