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Correcting wet or dry fingerprint images:
When the temperature is very cold or just after washing hands, fingerprints
often become very dry. In this case, the user should moisturize his/her
fingerprint simply by breathing on the fleshy pad of his/her fingertip prior
to placing his/her finger on the sensor. The moisture from his/her breath
transferred to his/her finger should help improve the recognition of his/her
fingerprint.
Conversely, if the fingerprint is too wet, the ridges and valleys are
rendered indistinguishable. The lack of recognizable minutiae causes wet
fingerprints to be rejected by the F707/708. This can be remedied simply
by swiping the finger on a clean dry towel or cloth.
How much pressure is required for a
good-quality fingerprint?
If too much pressure is applied to the sensor window, the finger’s ridges
become pressed together and create an indistinguishable image. Applying
too much pressure (similar to fingerprints that are too wet) will create a
“blurred” image which the F707/708 sensor might not recognize. It is
similar to using too much ink on a stamp; the stamp will create a smeared
image which is unrecognizable.
Conversely, if too little pressure is applied, the resulting image will be
similar to the dry fingerprint. Similar again to a stamp, if not enough ink is
used, the image will be barely recognizable.
Issues related to moisture and pressure are easily addressed. A little
practice is all that is needed for users to get the feel of it.
Be sure to maintain contact with the fingerprint sensor for 2 full
seconds, until the F707/708 responds. The F707/708 has both audio
and visual indicators which respond when the F707/708 senses a finger.
