Performance of biometric recognition systems degrades substantially as quality of the input samples drops. Although only a small fraction of input data are of poor-quality, the bulk of recognition errors can be attributed to poor-quality samples. If quality can be improved, either by sensor design, by user interface design, or by standards compliance, better performance can be realized. For those aspects of quality that cannot be designed-in, an ability to analyze the quality of a live sample is needed. This is useful primarily in initiating the reacquisition from a user, but also for the...