T H E
D E T A I L
Monday, June 23, 2003
BREAKING NEWz you can
compiled by Jon Stimac
More Accurate, Less Messy - THE
LONDON DAY, CT - June 21, 2003 ...will
this "new" fingerprinting method put ink-and-roll on back
Database Merge Off Schedule - ABC
NEWS - June 20, 2003
...the FBI and Immigration fingerprint
database merge is two years behind schedule...
Murder Case Nearly Three Decades Old - KFOX,
TX - June 21, 2003 ...There
was evidence at the scene that suggested that it could have been the
defendant, there was evidence at the scene that suggested it could have
been any number of other people whose prints were never identified...
Used to Tackle Fraud - BBC NEWS,
UK - June 17, 2003 ...some
UK shoppers are to be asked to provide a thumbprint on checks and credit
card transactions in an attempt to tackle fraud...
Good morning via the "Detail," a weekly e-mail newsletter that greets
latent print examiners around the globe every Monday morning. The purpose of the
Detail is to help keep you informed of the current state of affairs in the
latent print community, to provide an avenue to circulate original
fingerprint-related articles, and to announce important events as they happen in
Dates to register for the IAI conference in Ottawa are quickly
approaching. The program is going to be excellent, so if you are deciding
whether or not to register, go ahead and go for it. The host hotel is
full, but last time I checked the overflow hotel (Les Suites) still had some
rooms available. You can register online at www.theiai.org.
Last week, Lee Stonebreaker shared an idea regarding processing thermal paper
for latent prints. This
week, I wanted to throw out an interesting conept for discussion. I
have recently been involved in a small validation project which has required the
creation of two different databases of latent print images which were as close
to the same as possible. In order to get the best results possible, I came
up with a 5-point grading scheme for latent prints that I wanted to run by
everyone. I know this is not by any stretch of the imagination a
comprehensive list of factors, but I feel it fairly adequately addresses the
major factors involved in how difficult or easy a particular comparison might
be. (given standard inked prints to compare) I am interested in the
discussion on the back end of this week's Detail, so if you are reading along
and think of something else, or if you have dealt with this issue before and
have some thoughts, please drop by the Message Board and share your viewpoints.
The first element was QUANTITY, graded on a scale of 1 to 10. If the print
appeared to be about as large as a latent print from that finger could be, it
would get a 9 or 10. On the other hand, the smallest area of impression
possible to identify (0 to 10% of the source), it would get a "1".
The second element was CLARITY, also graded on a scale of 1 to 10. There
is a lot that goes into clarity, but the major factor I was considering was how
clear ridge features appeared. A "1" in this category might be a
latent print which was completely out of focus, or possibly just black ridges in
a heavy matrix which showed no pore or edge detail at all. Of course, the
opposite end of the spectrum, a "10", would be reserved for the most
pristine latent prints, displaying abundant pore and edge detail in very sharp
focus. Naturally, different types of distortion will affect over-all
clarity, but the scale takes this into account as a general part of
The third element was CONTRAST. On our same scale, a "1" would
go to a print which was barely discernable, while a "10" would be
given to a print which displayed a full range of grayscale over the entire ridge
system. This went hand in hand with the next element:
The fourth element was contrast SHIFT. Some prints displayed about a
"5" in terms of contrast, but some were lighter and others were
darker, so I created this category to refer specifically to the direction the
print shifted from "middle" gray. A "1" in this
category would be print displaying very light ridge detail on a white
background, and a "10" would be almost black ridges on a black
background. Of course, a "5" would be a latent print which
displayed grayscale ranges approximately half-way between pure white and pure
The fifth and final element was SURFACE. This involved generally how the
detail of the image was affected by the background (substrate) noise, but for my
study this ended up simply being a distinction between porous and non-porous,
for simplicity sake. Another scale of 1-10 would have probably been too
much for the results I was trying to achieve.
So the question is: what do you think? Did these factors address most of
what it would take to grade a latent print? Would there be anything else
you would add to get a significantly more complete picture of a latent print?
Theoretically, a latent print "3,5,3,2,p" would be approximately the
same difficulty level as a "3,4,4,3,p" but completely different than a
"8,2,6,9,n". I feel I was able to use these grading codes to
pair up prints in two different databases, resulting in two groups of nearly
identical difficulty, but containing different images. I was also able to
pick a range of difficulty based on an objective analysis of each print before
the selection, avoiding claims that I was seeing more or less of a particular
factor because that was what was needed to pair those prints. Your
feedback on the CLPEX message
board would be greatly appreciated: (http://www.clpex.com/phpBB/viewforum.php?f=2)
And as usual, the onin.com forum
(http://onin.com/fp/wwwbd/) is also available for more formal latent
For discussions with an international flair, check out Dave Charlton's forum at:
The "FFF" folder is
empty, so if you find something interesting while you are surfing the net, send
CLPEX.com this week...
No major updates on the site
Feel free to pass The Detail along to other examiners. This is a free
newsletter FOR latent print examiners, BY latent print examiners. There are no
copyrights on The Detail, and the website is open for all to visit.
If you have not yet signed up to receive the Weekly Detail in YOUR e-mail inbox,
go ahead and join the list now
so you don't miss out! (To join this free e-mail newsletter, send a blank
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to work things out.
Until next Monday morning, don't work too hard or too little.
Have a GREAT week!