1. A computer system for imaging fingerprints, comprising: a computer comprising a user interface, a central processing unit (CPU), a data storage that contains a plurality of data records representing one or more fingerprint images and an image capturing subsystem that produces an image of a target fingerprint; a feature extractor that produces one or more features from the target image; and a distance measuring unit that determines a distance along a path between any two of the features, said distance being determined in units of a number of ridges running between the two features, where the feature extractor further determines a feature confidence of one or more pixels on the path, and where the distance measuring unit is responsive to an occurrence of an invalid pixel on a path between two features for invalidating a distance measurement between the two features.