Document Liveness Details

Applies to: Direct | Capture

The document liveness signal in the /start endpoint returns a corresponding document liveness response in the get-results endpoint.

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Document liveness checks can help you evaluate an ID for document fraud. Document liveness is available for both Capture and Direct.

When you include the document_liveness_idrnd signal in the /start request body, we perform three document liveness checks. Check results are part of a document_livenessIdRnD object in the /get-results response, as follows:

• A screen replay (screenReplay) result. Was the document most likely captured from a device screen or monitor?
• A printed copy (printedCopy) result. Was the document most likely a printed copy or photocopy of a physical ID document?
• A portrait substitution (portraitSubstitution) result. Was the document most likely submitted with an altered or substituted portrait image?

Each of these three results is an object that includes a live property [0, 1] to indicate whether the document passed the check. If live is zero (0), then the document did not pass.

To arrive at alive result, we evaluate two other properties for each check: probability and threshold.

• The probability value is a confidence estimate (any number between 0 and 1) that the document passed the check. For example, if probability for screenReplay is 0.01, there is a very low likelihood (1%) that the document passed the check.
• The threshold value is a confidence cutoff that applies to probability. It is typically set at 0.8, which means the probability must be 80% or greater for the document to pass. When compared to probability, the threshold parameter determines the live result.

By way of illustration, if probability is less than threshold (for example, 0.01 < 0.8), then live is set to 0, meaning the document failed its check.

In the opposite way, if probability is greater than or equal to threshold (for example, 0.99 >= 0.8), then live is set to 1, meaning the document passed its check.

The three document liveness checks (screenReplay, printedCopy, and portraitSubstitution) can be performed for the front or back of a document. If any one of them returns a live result of 0, then the overall live result for that side of the document is also 0, meaning that side of the document failed one or more checks.