Problems of distorted fingerprints

Fingerprint recognition is the most popular system of biometric identification. The cost effective device, accuracy and the unique properties of fingerprint are the main reasons of popularity. However, fingerprint distortion is a major problem of fingerprint identification system. The scientists are trying hard to solve this problem. The article proposes a new technology of fixing the problem of distorted fingerprint.

In the digital age, automatic scanner determines the similarity between the two fingerprint images comparing the patterns of friction ridges and local distribution of the minutiae points. Therefore, the first step of fingerprint identification is capturing the images of friction ridges. In the traditional process, fingerprint image is captured by pressing the finger on a solid surface like prism or scanner. Uniform pressure on the scanner surface will produce a perfect image of fingerprint. However, if the finger applies non uniform pressure on the surface, a non linear distortion will occur. Besides this, distortions also occur due to damaged finger, oil and dirt on the finger. Elimination of non-linear distortion is a formidable challenge to the forensic experts.

Various methods are used to counter the non-linear distortion problem of fingerprint identification. Some fingerprint scanners measure the applied force and creates algorithm on the basis of applied pressure. This system does not work when the distortion is too large. Most of them are based on the algorithm of non-linear distortion. However, these methods are appropriate for comparing the non-distorted and distorted fingerprints. This process does not produce good result in the case of matching two distorted fingerprints.

Fingerprint matching is done by comparing the ridge structures of two and more fingerprint impressions and their spatial distribution of minutiae points. To counter the problem of distorted fingerprint impression, the scientists developed a device that can capture the three dimension (3D) image of friction ridges. In this system, an optical 3Dcamera system generates a high quality image by covering a bigger part of finger skin. 3D optical has introduced touch less imaging system and it provides more details about fingerprint ridges. The system uses the technology of capturing the image without contact between the finger and a solid surface. Therefore, the possibility of deformed image has been substantially reduced. The key feature of the technique is to transform the topological pattern of fingerprint into coordinate system. This allows the forensic experts to unwrap the distorted fingerprint and create an authentic representation of fingerprint impressions.