(Part of the biometric product marketing expert series)
For many years, the baseline for high-quality capture of fingerprint and palm print images has been to use a resolution of 500 pixels per inch. Or maybe 512 pixels per inch. Whatever.
The crime scene (latent) folks weren’t always satisfied with this, so they pushed to capture latent fingerprint and latent palm print images at 1000 pixels per inch. Pardon me, 1024.
But beyond this, the resolution of captured prints hasn’t really changed in decades. I’m sure some people have been capturing prints at 2000 (2048) pixels per inch, but there aren’t massive automated biometric identification systems that fully support this resolution from end to end.
But that may be changing.
One important truth about infant fingerprints
For about as long as latent examiners have pursued 1000 ppi print capture, people outside of the criminal justice arena have been looking at fingerprints for a very different purpose.
Our normal civil fingerprint processes require us to identify people via fingerprints beginning at the age of 18, or perhaps at the age of 12.
But gow do we identify people in those first 12 years?
More specifically, can we identify someone via their fingerprints at birth, and then authenticate them as an adult by comparing to those original prints?
It’s a dream, but many have pursued this dream. Dr. Anil Jain at Michigan State University has pursued this for years, and co-authored a 2014 paper on the topic.
Given that children, as well as the adults, in low income countries typically do not have any form of identification documents which can be used for this purpose [vaccination], we address the following question: can fingerprints be effectively used to recognize children from birth to 4 years? We have collected 1,600 fingerprint images (500 ppi) of 20 infants and toddlers captured over a 30-day period in East Lansing, Michigan and 420 fingerprints of 70 infants and toddlers at two different health clinics in Benin, West Africa.
At the time, it probably made sense to use 500 pixel per inch scanners to capture the prints, since developing countries don’t have a lot of money to throw around on expensive 1000 ppi scanners. But the use of regular scanners runs counter to a very important truth about infants and their fingerprints. Are you sitting down?
Because infants are smaller than adults, infant fingerprints are smaller than adult fingerprints.
Think about it. The standard FBI fingerprint card assumes that a rolled fingerprint occupies 1.6 inches x 1.5 inches of space. If you were to roll an infant fingerprint, it would occupy much less than that. Heck, I don’t even know if an infant’s entire FINGER is 1.6 inches long.
So the capture device is obtaining these teeny tiny ridges, and these teeny tiny ridge endings, and these teeny tiny bifurcations. Or trying to. And if those second-level details can’t be captured, then you’re not going to get the minutiae, and your fingerprint matching is going to fail.
So a decade later, researchers today are adopting a newer approach, according to a Biometric Update summary of an ID4Africa webinar. (This particular portion is at the very end of the webinar, at around the 2 hour 40 minute mark.)
A video presentation from Judge Lidia Maejima of the Court of Justice of Parana, Brazil introduced the emerging legal framework for biometric identification of infants. Her representative Felipe Hay explained how researchers in Brazil developed 5,000 dpi scanners, he says, which accurately record the minutiae of infants’ fingerprints.
Did you capture that? We’re moving from five hundred pixels per inch to FIVE THOUSAND pixels per inch. (Or maybe 5120.) Whether even that resolution is capable of capturing infant fingerprint detail remains to be seen.
And as Dr. Joseph Atick noted, all this research is still in its…um…infancy. We won’t know for years whether the algorithms can truly match infant fingerprints to child or adult fingerprints.
By the way, when talking about digital images, Adobe notes that the correct term is pixels per inch, not dots per inch. DPI specifically refers to printer resolution, which is appropriate when you’re printing a fingerprint card but not when you’re displaying an image on a screen.
(Image from From https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.500-290e3.pdf )
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