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John Bredehoft
Posted on Monday, July 10, 2006 - 05:30 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

The TBS touchless fingerprinting presentation at the July 2006 IAI conference in Boston touched on this topic and showed some examples of the differences between a fingerprint captured via a touchless device (i.e. no pressure) and a fingerprint captured via a pressure method.
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lennybutt
Posted on Sunday, March 19, 2006 - 03:24 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

About 11 years ago I saw a presentation (I believe it was conducted in the Netherlands)dealing with the ability of one AFIS vendor's system to locate the corresponding respondent record when the size of the latent print had been altered. Their study did not address true distortion, but the data did reveal that the tested system had more difficulty in matching the records when the search print was reduced in size.

In addition AFIS user's are trained to enter clusters of features when latent prints are encoded rather than selecting all of the available features in a print. This practice helps to limit the impact that distortion has on the matching process.
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Webservant
Posted on Saturday, March 18, 2006 - 08:20 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Pressure distortion is present to varying degrees in every record or latent finger/palm print.

If it were not so, fingerprint experts would not be needed because you could merely overlay transparencies of latent and record prints to see the undistorted, exact correlation. AFIS technology is very robust insofar as compensating for distortion caused by various factors, including (but not limited to) pressure distortion, slippage during touch, substrate/processing factors, and growth (a felon who gains 200 pounds between the time he/she deposited a latent print and is fingerprinted for searching in AFIS).

AFIS provides the 20 (or 10, 50, etc., depending on system settings) highest scoring correlations from a database. Fingerprint experts then sort through the candidates to determine if an identification exists. Distortion can preclude the true-matching candidate from appearing in the potential match list unless the AFIS matching technology is robust enough to compensate for distortion.
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kris
Posted on Thursday, March 16, 2006 - 03:13 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Hi I am a 2nd year forensic science student and for my 3rd year project i want to do a project based on whether pressure distortion effects a print and if this makes it more difficult for a match on AFIS. I would also be grateful to know if any other studies have been done for this

Thank you

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