Interpretation of Result and Recommended Threshold

OkayLive - Liveness detection

Key	Value
probability	Probability of liveness Note: Recommended Threshold = 0.5
score	Linear liveness score: bigger value means more alive, (Not suggested as a threshold to detect the liveness.)
quality	Quality Value Note: Recommended Threshold = 0.5
error	Error message from the server

The response of "score" is NOT suggested to be used for the decision-making for detection results.

• The probability of liveness is the main response of the system.

• The image is accepted as "live" when a probability is bigger than 0.5.

• Linear liveness score can be used for BPCER / APCER tuning. The range of score is (ln 1e-7, -ln 1e-7).

• The quality value is the probability of a "clear image" to indicate the quality of the selfie image.

• A good quality selfie image, the quality will be bigger than 0.5

• The probability can be lower than 0.5 for the reasons below.

  • Face minimal side is less than 180 pix or distance between eyes is less than 90 pix.

  • Face out-of-plane rotation is bigger than 20 degrees.

  • The distance between the face and the camera is very small, so the face can be significantly distorted.

  • The luminous power is insufficient.

  • High motion or gaussian blur rate or light shot.

We highly advise analyzing quality value and rejecting inappropriate images.