Detect, observe, recognise, identify: the four levels of CCTV evidence
KINNEX Team5 min read
Footage that cannot answer “who was it” is only a recording. International practice, reflected in standards such as IEC 62676-4, describes four levels of image detail.
The four levels
- Detect: you can tell that something is there, such as a person or a vehicle.
- Observe: you can see characteristics, such as clothing or the direction of travel.
- Recognise: you can tell whether someone is a known person, with high confidence.
- Identify: you can establish who someone is beyond reasonable doubt.
Each level needs more pixels across the subject. The numbers are usually expressed as pixels per metre at the target distance, with the higher levels needing several times more than the lowest.
Why it matters
A camera covering a whole car park may detect movement, but never identify anyone. A camera at the entrance, aimed at faces, can. Designing every camera to the same level wastes money in some places and fails in others.
How designers apply it
For each camera position, decide the required level. Calculate the field of view, resolution and lens needed to reach it at the real distance. Check lighting, glare and mounting height. Then confirm with a test, not a datasheet.
A practical rule
Use wide cameras for detection and awareness, and dedicated cameras at doors, gates and counters for recognition and identification.