The ridge flow constitutes a global pattern of the fingerprint. First, the image is enhanced. Then, there is ridge extraction, thinning and feature extraction. Templates are compared at the verification stage. The second category of fingerprint analysis is verification.
Verification is the comparison of a claimant fingerprint against an enrollee fingerprint.
The intention is to match the claimant print against the enrollee print, in order to determine if the claimant is in fact the enrollee. To prepare for verification, a person initially enrolls his or her fingerprint into the verification system and is certified by some authority. A representation, or template, of that fingerprint is stored in some compressed form, along with the person's name or other identity. If the highest level of security is required, the authority can digitally sign that template so that an attacker cannot substitute a counterfeit enrollee template. Clearly, fingerprint analysis is a methodical process.