When applying digital signatures, you are expected to perform a certain amount of spot-checks. These checks will ensure that the original paper documents and their resulting digital images are (more or less) identical.
Threshold
The threshold value specifies the percentage of scanned images (from an entire batch) an operator must inspect and confirm, before digital signatures are enabled.
Threshold per document
The threshold per document value determines the percentage of scanned documents an operator must inspect and confirm, before digital signatures is enabled.