Department of Mathematics

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IIT Jodhpur

This paper develops a methodology to generate a sequence of interval vectors (boxes), which converges to a very small box of negligible volume containing the minimum point a function of several variable. Each point of that box is an approximate solution. Interval extension of real valued function is used to propose the method. © 2012 Newswood Limited. All rights reserved.

World University root node

Lecture Notes in Engineering and Computer Science

Minimizing a function using a sequence of interval vectors

For nanostructures such as semiconductor quantum dot emitters or biological systems like light harvesting complexes (photosynthesis) the coupling between individual constituents leads to the formation of delocalized exciton states. Coherent two dimensional spectroscopy is a versatile tool to investigate the structure of the excitonic states, whereas nanoplasmonics allows to localize optical fields on a nanoscale: We combine these two methods in a theoretical study and propose new experiments, such as the two dimensional spectra containing spatial resolution via localized fields. Using post processing of different spectra with localized fields, we can enhance certain spectroscopic features in standard coherent spectroscopy, e.g. by suppressing unwanted resonances. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Proceedings of SPIE - The International Society for Optical Engineering

Combining nanooptical fields and coherent spectroscopy on systems with delocalized excitons

In this paper, a security solution for stereo images during communication and transmission is proposed. For this purpose, a robust stereo-image coding algorithm via encryption technique is proposed using step space filling curve, non-linear chaotic map and singular value decomposition. The core idea is to first encrypt the left and right stereo images followed by the merging process of left and right stereo images into single image which further treated as final encrypted image. The final encrypted image is transmitted over the insecure channel. At the receiver end, left and right encrypted images are extracted from final encrypted image followed by the decryption process. The efficiency and the robustness of the proposed algorithm are demonstrated by different experiments and analysis on different stereo image pairs. © 2012 American Scientific Publishers All rights reserved.

Advanced Science Letters

Security of stereo images during communication and transmission

In this paper, a security solution during communication and transmission of fingerprint data is proposed in the form of a novel encryption technique based on reversible hidden transform (RHT) and fractional wavelet packet transform (FrWPT). The core idea of the proposed technique is to change the gray values in the spatial domain using RHT followed by the deformation of FrWPT coefficients by singular value decomposition and chaotic map. Hence, security solution relies on both spatial and frequency domains. Finally, a reliable decryption scheme is also presented to reconstruct the original fingerprint image from the encrypted image. Experimental results and security analysis demonstrate the efficiency and robustness of the proposed scheme. © 2012 IEEE.

IEEE Transactions on Instrumentation and Measurement

Chaos-based security solution for fingerprint data during communication and transmission

Nonlocal material response distinctively changes the optical properties of nano-plasmonic scatterers and waveguides. It is described by the nonlocal hydrodynamic Drude model, which - in frequency domain - is given by a coupled system of equations for the electric field and an additional polarization current of the electron gas modeled analogous to a hydrodynamic flow. Recent attempt to simulate such nonlocal model using the finite difference time domain method encountered difficulties in dealing with the grad-div operator appearing in the governing equation of the hydrodynamic current. Therefore, in these studies the model has been simplified with the curl-free hydrodynamic current approximation; but this causes spurious resonances. In this paper we present a rigorous weak formulation in the Sobolev spaces . H(curl) for the electric field and . H(div) for the hydrodynamic current, which directly leads to a consistent discretization based on Nédélec's finite element spaces. Comparisons with the Mie theory results agree well. We also demonstrate the capability of the method to handle any arbitrary shaped scatterer. © 2012 Elsevier Inc.

Fulltext

Journal of Computational Physics

Numerical solution of nonlocal hydrodynamic Drude model for arbitrary shaped nano-plasmonic structures using Nédélec finite elements

In this study, the concept of fractional wavelet packet transform is explored with its application in digital watermarking. The core idea of the proposed watermarking scheme is to decompose an image via fractional wavelet packet transform and then a reference image is created by changing the positions of all frequency sub-bands at each level with respect to some rule which is secret and only known to the owner/creator. For embedding, the reference image is segmented into non-overlapping blocks and modify its singular values with the watermark singular values. Finally, a reliable watermark extraction algorithm is developed for the extraction of watermark from the distorted image. The feasibility of this method and its robustness against different kind of attacks are verified by computer simulations. © 2012 The Institution of Engineering and Technology.

IET Image Processing

Robust watermarking using fractional wavelet packet transform

In this paper, the dual tree complex wavelet transform, which is an important tool and recent advancement in signal and image processing, has been generalized by coalescing dual tree complex wavelet transform and fractional Fourier transform. The new transform, i.e. the fractional dual tree complex wavelet transform (FrDT-CWT) inherits the excellent mathematical properties of dual tree complex wavelet transform and fractional Fourier transform. Possible applications of the proposed transform are in biometrics, image compression, image transmission, transient signal processing etc. In this paper, biometric is chosen as the primary application and hence a new technique is proposed for securing biometrics during communication and transmission over insecure channel. © 2010 Elsevier B.V. All rights reserved.

Future Generation Computer Systems

Fractional dual tree complex wavelet transform and its application to biometric security during communication and transmission

In this paper, a robust logo watermarking scheme based on image fusion is proposed. Unlike existing watermarking schemes, the used watermark is a gray scale logo instead of randomly generated Gaussian noise type watermark. The core idea of the proposed scheme is to decompose an image into frequency sub-bands using wavelet transform followed by the embedding in selected blocks of sub-bands obtained by ZIG-ZAG sequence. Block selection is done by taking variance of the blocks into consideration. The experimental results show better visual imperceptibility and resiliency of the proposed scheme against intentional or un-intentional variety of attacks and superiority is carried out by comparison made by us with the existing schemes. © 2012 Elsevier Ltd. All rights reserved.

Computers and Electrical Engineering

Robust gray-scale logo watermarking in wavelet domain

In this paper, a new encryption scheme with three different modes of operations is proposed based on dual space-filling curves (SFSs) and a fractional wavelet transform (FrWT). This scheme is initially proposed for images and then extended to videos. The core idea behind the proposed schemes is to decompose an image/video first by the FrWT followed by the shuffling of each sub-band coefficients by means of a dual SFC. At last, an inverse FrWT is performed to get the encrypted image/video. A reliable decryption process is also proposed to construct the original image from the encrypted image. The experimental results, security and comparative analysis demonstrate the efficiency and robustness of the proposed scheme. Further, this paper also proposes an efficient implementation of an FrWT based on chaotic maps. © 2011 The Author. Published by Oxford University Press on behalf of The British Computer Society. All rights reserved.

Computer Journal

Image and video encryption based on dual space-filling curves

In this paper, a novel image fusion algorithm based on framelet transform is presented. The core idea is to decompose all the images to be fused into low and high-frequency bands using framelet transform. For fusion, two different selection strategies are developed and used for low and high-frequency bands. The first strategy is adaptive weighted average based on local energy and is applied to fuse the low-frequency bands. In order to fuse high-frequency bands, a new strategy is developed based on texture while exploiting the human visual system characteristics, which can preserve more details in source images and further improve the quality of fused image. Experimental results demonstrate the efficiency and better performance than existing image fusion methods both in visual inspection and objective evaluation criteria. © 2012 World Scientific Publishing Company.