19-03-2011, 02:20 PM
Presented by
PANCHANAN PATTANAIK
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INTRODUCTION
The Fingerprint Recognition system is a new part of biomatrics.
It provides an exciting look into the future.
Basically devided into two types-
Enrollment
Recognition
Enrollment
Enrollment can be further organized into three steps-
Image Capture
Signature Extraction
Storage
Image capture
Image capture consists of obtaining an image of the fingerprint.
Typically, resolution is 500 dpi which corresponds to a pitch of 50 microns.
In the real world, there are some systems that use only one bit per pixel or binary fingerprint images.
Signature Extraction
Storing of images consumes much memory.
So the fingerprint image is processed in order to obtain a signature or template.
A template is a compressed version of fingerprint image,with losses.
After passing the image through several filters only the relative coordinates of minutiae are stored which are very small in size.
30 to 40 minutiae cost around 256 bytes.
A less compact technique from storage point of view is direrct optical correlation.
Storage
Once the template is obtained,it is stored for further recognition.
Recognition
The Recognition Process follows the same steps as Enrollment with the addition of other.
The process includes
Image Capture
Signature Extraction
Matching
The Matching can be devided into two types
One to one(Verification)
One to many(Identification)
One to one may be a kind of one to few.
Verification takes less computing time than Identification hence vastly used in commercial application.
Fingerprint sensing Techniques
There are different techniques for sensing the fingureprints such as
Optical
Ultrasound
Silicon chip
Optical Scanners
Silicon sensors compared with others
Siliconize does matter
Cost is very important factor when considering biometric technology.
As far as Si is concerned lower the area lower is the price.
Moreover lower the area lesser is the probability of defect.
Sweeping technique
Unfortunately fingerprint imaging is very difficult for small Si chips.
Hence the Sweeping technique has been devloped.
Here the user have to sweep his/her finger over a thermal rectangular array.
This method uses several lines per slice and search identical pixels between each slice.
Security
The security may be devided into two parts
Living security
Electronic securityThe system on a chip
The sensor ,processor,associated memory and reference storage may be planted on a single chip.
But the limitation is the cost.
We can implement ciphering techniques on the sensors as in smart-cards.
But it may effect the security.
Authentication
We may use a smart card with the fingerprint signature reference and a device able to extract the signature.
But the processor that performs matching may be corrupted.
Hence the matching software must be written on the smart-card which results uncorrupted matching.
Authentication
This kind of smart card may be quite universal and unusable if stolen.
But the only limitation will be the standardization of the software.
It must be able to work with any fingerprint reader and variety of signature extraction softwares.
Authentication
A better system is a smart-card which performs the whole process i.e. image capture,signature extraction,matching with a single chip.
It may overcome the standardization process but it has some limitations.
Required CPU power.
Cost of the card.
Technical difficulties related to thickness of card
Size of the silicon chip.
Conclusion
Fingerprint sensing silicon chips are the future of inexpensive fingerprint imaging and help to increase security and efficiency.
Use of CMOS components enables further system integration and hence greater security.
High initial costs may slow the integration process but we can expect cost reductions and new possibilities with microelectronics.