Primary objective of fingerprint scanners are to produce best possible fingerprint patterns for conversion into digital templates. Different sensors could be used to extract multiple minutiae sets from the fingerprints for the purpose of identification or verification. Optical sensors being more economical than other sensor technologies, are used widely in biometric systems across industries. Following some simple instructions, optimal image quality could be obtained seamlessly from these scanners for every impression.
Optical sensors typically make use of minutiae for extracting information about the fingerprints and consequently convert them into templates using intricate algorithms that form the base for enrollment and matching. If the scanned fingerprint is not optimal as per the standards required then the minutiae thus extracted would also not be reliable enough to be used for matching. There are many variants that lead to unsatisfactory minutiae such as skin conditions (too wet or dry), external environment, inappropriate contrast on device, etc. Changing the scanning quality of the sensor in such scenarios would generally solve these problems.
These sensors in most cases could extract the optimal minutiae using the various extraction techniques even if the finger is not placed correctly on the touch surface. Though, to get consistent results all the time, correct placement of finger on the scanning surface is imperative. As a general rule, the pad (fleshy middle part near the tip of the finger) should cover as much surface area on the scanner as possible. Also, the pressure applied with the finger must not be excessive or too less. It should be placed gently with a little press. It is always useful to enroll with more than one finger so as to use the other finger for recognition in case of finger injury or cut.
Most of the fingerprint biometric systems used worldwide, offer software applications with these scanners that can adjust scanning quality automatically. By placing your finger on the touch surface, the application itself would take into account existing environmental factors and automatically adjust the scanning quality. To clean the touch surface, never apply any cleaning agent directly onto it as the liquid could permeate the glass and damage the phosphorous layer beneath it. Also, use of strong cleaning agents must be avoided.