The Hong Kong Polytechnic University (PolyU)

Finger-Knuckle-Print Database


Among various kinds of biometric identifiers, hand based biometrics has been attracting considerable attention. Recently, it is found that the finger-knuckle-print (FKP), which refers to the inherent patterns of the outer surface around the phalangeal joint of one’s finger, is highly unique and can serve as a distinctive biometric identifier. Abundant line-like textures are contained in an FKP image.

The Biometric Research Centre (UGC/CRC) at The Hong Kong Polytechnic University has developed a real time FKP capture device, and has used it to construct a large-scale FKP database. To advance research and to provide researchers working in the area of FKP recognition with a platform to compare the effectiveness of various FKP recognition algorithms, we intend to publish our FKP database, making it freely available for academic, noncommercial uses.


(a) The outlook of the FKP image acquisition device; (b) The device is being used to collect FKP image samples.

Description of the PolyU FKP Database:

FKP images were collected from 165 volunteers, including 125 males and 40 females. Among them, 143 subjects were 20~30 years old and the others were 30~50 years old. We collected samples in two separate sessions. In each session, the subject was asked to provide 6 images for each of the left index finger, the left middle finger, the right index finger, and the right middle finger. Therefore, 48 images from 4 fingers were collected from each subject. In total, the database contains 7,920 images from 660 different fingers. The average time interval between the first and the second sessions was about 25 days. The maximum and minimum intervals were 96 days and 14 days, respectively.

Each folder is named as “nnn_fingertype”. “nnn” represents the identity of the person. In each folder, the first 6 images (01~06) were captured in the first session and the latter 6 images (07~12) were captured in the second session. “FKP” contains all the original FKP images collected with our device. We also provide the extracted ROI images using our ROI extraction algorithm described in [2]. ROI images are contained in “FKP”.

Embedded FKP Recognition System:

(a) The outlook of the embedded FKP recognition system; (b) The embedded FKP recognition system with the recognition software is running.

Recently, we have developed a standalone embedded FKP recognition system. Such a system can work alone without depending on any general-purpose computer. Users can operate the system via the tourch screen. This system has the merits of small size, fast speed, and low cost. The above two pictures show the outlook of the system. A video clip which demonstrates how this system works can be found at youtube or youku

Related Publication:

1.      Lin Zhang, Lei Zhang, David Zhang, and Zhenhua Guo, “Phase congruency induced local features for finger-knuckle-print recognition”, Pattern Recognition, vol. 45, no. 7, pp. 2522-2531, Jul. 2012.

2.      Lin Zhang, Lei Zhang, David Zhang, and Hailong Zhu, “Ensemble of local and global information for finger-knuckle-print recognition”, Pattern Recognition, vol. 44, no. 9, pp. 1990-1998, Sep. 2011.

3.      Lin Zhang, Lei Zhang, David Zhang, and Hailong Zhu, “Online finger-knuckle-print verification for personal authentication”, Pattern Recognition, vol. 43, no. 7, pp. 2560-2571, July 2010.

4.      Lin Zhang, Lei Zhang, and David Zhang, “Finger-knuckle-print: a new biometric identifier”, Proceedings of the IEEE International Conference on Image Processing, pp. 1981-1984, 2009.

5.      Lin Zhang, Lei Zhang, and David Zhang, “Finger-knuckle-print verification based on band-limited phase-only correlation,” Proceedings of the 13th International Conference on Computer Analysis of Images and Patterns, pp. 141-148, 2009.

The Announcement of the Copyright

All rights of the PolyU FKP Database are reserved. The database is only available for research and noncommercial purposes. Commercial distribution or any act related to commercial use of this database is strictly prohibited. A clear acknowledgement should be made for any public work based on the PolyU FKP Database. A citation to "PolyU FKP Database,” and our related works must be added in the references. A soft copy of any released or public documents that use the PolyU FKP Database must be forwarded to:

Downloading Steps:

Download “FKP” and “FKP” to your local disk. Then, fill in the application forms. Send the application form to The successful applicants will receive the passwords for unzipping the files downloaded.

FKP Database:


Application Form

Contact Information:

Lei ZHANG, Associate Professor

Biometric Research Centre (UGC/CRC)
The Hong Kong Polytechnic University
Hung Hom, Kowloon, Hong Kong