12-11-2012, 04:01 PM
DIGITAL IMAGE WATERMARKING BASED ON FPGA AND SPINTRONIC LOGIC AND STUDY OF SOME ASPECTS OF SPINTRONIC LOGIC BASED CIRCUITS
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ABSTRACT
The growth of high speed computer networks and that of Internet, in particular has explored means of new business , scientific , entertainment and social opportunities .Digital media offer several advantages over analog media like high quality ,easy editing ,high fidelity copying . There are enormous chances of duplicating and distribution of digital information which has led to the need for effective copyright protection tools . DIGITAL WATERMARKING is a kind of protection tool in which a data is hidden in an image ,audio file or video file .Watermarking is either ―visible‖ or ‖invisible‖ . Albeit visible or invisible are visual terms watermarking is not limited to images , it can also be used to protect other types of multimedia object . This project work is on Spatial Domain Image Watermarking using FPGA and Spintronic logic and applications of single spin logic where the spin of electron is used in addition to its charge .For the application of spintronics MAGNETIC TUNNEL JUNCTIONS (MTJ) are used as a spintronic device and different logic and ALU operations are performed and are compared with the conventional electronic devices based operation . The spintronic devices have lots of advantages over the conventional devices like they are non-volatile ,they consume less power ,timing and area.
INTRODUCTION TO WATERMARKING
The last decade has witnessed the rapid development in information technologies and the wide availability of digital consumer device such as digital cameras ,scanners etc .But at the same time this leads to the hacking vulnerability and duplicity of the original information.
The most modern solution technique to this problem is digital watermarking scheme .Digital watermarking algorithms could be considered as digital communication scheme where auxiliary message is embedded in digital multimedia signal and are available where ever the later signals move.
Watermarking is also a type of information hiding where secret codes are embedded in the hidden form inside an image file ,audio file or video file .Watermarking is a relatively new and unexplored field in which extensive research is going on all over the world and it has the potential to provide simple and easily implementable solution to provide rightful ownership.
CONCEPT OF WATERMARKING
Over the past few years ,several watermarking algorithms have been introduced and their software is accessible ,however recently some hardware realizations are being offered in the literature .Software implementations are easy to use, have upgradability and flexibility but it has limited speed problem and vulnerability to the offline attack.
Despite of that hardware implementation offer less area , low execution time and low power .Therefore , watermarking inside digital devices cannot assure the tamper proof . Hence for hardware implementation spatial domain is always preferred.
Spatial domain data embedding scheme and its hardware implementation in semi gate array ASIC(Application Specific Integrated Circuit ) -VLSI(Very Large Scale on Integration) as well as using spin based logic.
The quality of transmitted is also comparable to that of the implemented by the software .This reliability is further enhanced by using private key coding scheme.
WATERMARKING EMBEDDING AND DETECTION
The algorithm for the scheme is a kind of digital modulation scheme which uses synchronous detection for decoding of the information .Using LSB modulation method , a gray scale stego image called as modulated signal is produced in which buffer block is transforming 2-D pixel values to 1-D and unbuffer block for transforming 1-D pixel values to 2-D pixel values .At last ,the message is extracted at the receiver from the modulated signal using synchronous detection where the same buffer and unbuffer blocks are used for the very purpose.
FIELD-PROGRAMMABLE GATE ARRAY
A Field – programmable Gate Array (FPGA) an ―integrated circuit designed to be configured by the customer or designer after manufacturing—hence "field-programmable" . The FPGA configuration is generally specified using a hardware descriptilanguage(HDL),similar to that used for an application specific integrated circuit(ASIC) were previously used to specify the configuration ,as they were for ASICs, but this is increasingly rare. FPGAs can be used to implement any logical functions that an ASIC could perform . The ability to update the functionality after shippings , partial re - configuration of the portion of the design and the low non-recurring engineering costs relative to an ASIC design (notwithstanding the generally higher unit cost), offer advantages for many applications.
FPGAs contain programmable logic components called "logic blocks" , and a hierarchy of reconfigurable interconnects that allow the blocks to be "wired together" somewhat like many logic gates that can be inter-wired in different configurations‖[20]. Logic blocks can be configured to perform complex combinational functions , or merely simple logic gates like AND and XOR . In most FPGAs , the logic blocks also include memory elements , which may be simple flip-flops or more complete blocks of memory.