Department of Mathematics

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IIT Jodhpur

Most of the real world scenes have a very high dynamic range (HDR). The mobile phone cameras and the digital cameras available in market are limited in their capability in both the range and spatial resolutions. Same argument can be posed about the limited dynamic range of display devices which further differ in spatial resolution and aspect ratio. In this paper, we address the problem of displaying the high contrast low dynamic range (LDR) image of a HDR scene in a display device which has different spatial resolution compared to that of the capturing device. We want to achieve this task while preserving the salient scene contents. The solution proposed in this work can be employed with any camera which has the ability to shoot multiple differently exposed images of a scene. Further, the proposed solutions provide the flexibility in the depiction of entire contrast of the HDR scene as an LDR image with user specified spatial resolution. This task is achieved through an optimized content aware retargeting framework which preserves the salient features apart from a novel algorithm to fuse multi-exposure images. We show that the proposed approach performs exceedingly well in the generation of high contrast LDR image of varying spatial resolutions. © 2014 IEEE.

World University root node

Proceedings of the 5th International Conference on Confluence 2014: The Next Generation Information Technology Summit

Efficient image retargeting for high dynamic range scenes

We investigated the effect of Au nanoparticles in Zinc o xide semiconductor matrix for enhanced absorption. Apart from ZnO optical absorption at 360 n m, the matrix also shows plasmonic absorption at 560 nm. © OSA 2014.

Proceedings 12th International Conference on Fiber Optics and Photonics, Photonics 2014

Plasmon enhanced absorption in Au:ZnO hybrid systems

The effect of velocity slip at the walls on the linear stability characteristics of two-fluid three-layer channel flow (the equivalent core-annular configuration in case of pipe) is investigated in the presence of double diffusive (DD) phenomenon. The fluids are miscible and consist of two solute species having different rates of diffusion. The fluids are assumed to be of the same density, but varying viscosity, which depends on the concentration of the solute species. It is found that the flow stabilizes when the less viscous fluid is present in the region adjacent to the slippery channel walls in the single-component (SC) system but becomes unstable at low Reynolds numbers in the presence of DD effect. As the mixed region of the fluids moves towards the channel walls, a new unstable mode (DD mode), distinct from the Tollman Schlichting (TS) mode, arises at Reynolds numbers smaller than the critical Reynolds number for the TS mode. We also found that this mode becomes more prominent when the mixed layer overlaps with the critical layer. It is shown that the slip parameter has nonmonotonic effect on the stability characteristics in this system. Through energy budget analysis, the dual role of slip is explained. The effect of slip is influenced by the location of mixed layer, the log-mobility ratio of the faster diffusing scalar, diffusivity, and the ratio of diffusion coefficients of the two species. Increasing the value of the slip parameter delays the first occurrence of the DD-mode. It is possible to achieve stabilization or destabilization by controlling the various physical parameters in the flow system. In the present study, we suggest an effective and realistic way to control three-layer miscible channel flow with viscosity stratification. © 2014 AIP Publishing LLC.

Fulltext

Physics of Fluids

Double-diffusive two-fluid flow in a slippery channel: A linear stability analysis

In this paper, a chaotic encryption framework is proposed for enhancing the security of biometrics images during transmission. The proposed framework is based on the fractional wavelet packet transform (FrWPT), chaotic map and Hessenberg decomposition. The core idea is to shuffle biometrics image using affine transform followed by the transformation in FrWPT domain with chaotically generated transform orders. Now, FrWPT coefficients are altered using the Hessenberg decomposition. Finally, a reliable decryption process is presented to reconstruct original biometrics image from the encrypted data only with the valid keys. The efficiency and robustness of the proposed technique are validated by different kind of simulations and analysis on fingerprint images. © 2013 Springer-Verlag Berlin Heidelberg.

Multimedia Systems

Enhancing the transmission security of biometric images using chaotic encryption

This paper presents an analysis of the multiresolution form of singular value decomposition SVD (MR-SVD) and generalizes the analysis into a random multiresolution form of singular value decomposition (R-MR-SVD) with an intrinsic randomness. The core idea behind the proposed transform is to introduce randomness in the computing process based on parameters without which one can neither decompose nor reconstruct the data correctly. The proposed transform inherits the excellent properties of MR-SVD along with its own unique features, which can be useful in many research areas. Image encryption, lossy image compression, and face recognition are the primary applications used to illustrate the practical usage of the proposed transform. © 2014 Elsevier Inc. All rights reserved.

Information Sciences

Analysis and extension of multiresolution singular value decomposition

One of the foremost requisite for human perception and computer vision task is to get an image with all objects in focus. The image fusion process, as one of the solutions, allows getting a clear fused image from several images acquired with different focus levels of a scene. In this paper, a novel framework for multi-focus image fusion is proposed, which is computationally simple since it realizes only in the spatial domain. The proposed framework is based on the fractal dimensions of the images into the fusion process. The extensive experiments on different multi-focus image sets demonstrate that it is consistently superior to the conventional image fusion methods in terms of visual and quantitative evaluations. © 2013 IEEE.

2013 4th National Conference on Computer Vision, Pattern Recognition, Image Processing and Graphics, NCVPRIPG 2013

A novel framework for multi-focus image fusion

Whispering gallery modes supported by open circular dielectric cavities are embedded into a nonparametric two-dimensional frequency domain hybrid coupled mode theory framework. Regular aggregates of these cavities, including straight access channels, are investigated. The model enables convenient studies of the guided wave scattering process, the response of the circuit to guided wave excitation. Transmission resonances can be characterized directly in terms of resonance frequency and linewidth by computing supermodes of the entire composite circuits, comprising both cavities and bus waveguides. Examples of single ring and disk filters, a coupled-resonator optical waveguide, and a three-cavity photonic molecule in a reflector configuration allow the approach to be assessed. © 2013 Optical Society of America.

Journal of the Optical Society of America B: Optical Physics

Interaction of whispering gallery modes in integrated optical microring or microdisk circuits: Hybrid coupled mode theory model

Generally, in watermarking scheme the size of the watermark is very small when compare to host image. On the contrary, this is an attempt in which a new watermarking scheme is presented where the size of host image is very small when compare with watermark image. The core idea of the proposed scheme is to scale up the size of host image equal to the size of watermark via over-sampling and then decompose it using stationary wavelet transform. A gray scale watermark is embedded in the low frequency sub-band at the finest level using singular value decomposition. To prevent ambiguity and enhance the security, a binary watermark is also embedded in loss-less manner. Finally, a reliable watermark extraction scheme is developed for extracting both the watermarks. The experimental results demonstrate better visual imperceptibility and resiliency of the proposed scheme against intentional or un-intentional variety of attacks. © 2011 Springer Science+Business Media, LLC.

Multimedia Tools and Applications

A new aspect in robust digital watermarking

Multimodal medical image fusion, as a powerful tool for the clinical applications, has developed with the advent of various imaging modalities in medical imaging. The main motivation is to capture most relevant information from sources into a single output, which plays an important role in medical diagnosis. In this paper, a novel fusion framework is proposed for multimodal medical images based on non-subsampled contourlet transform (NSCT). The source medical images are first transformed by NSCT followed by combining low- and high-frequency components. Two different fusion rules based on phase congruency and directive contrast are proposed and used to fuse low- and high-frequency coefficients. Finally, the fused image is constructed by the inverse NSCT with all composite coefficients. Experimental results and comparative study show that the proposed fusion framework provides an effective way to enable more accurate analysis of multimodality images. Further, the applicability of the proposed framework is carried out by the three clinical examples of persons affected with Alzheimer, subacute stroke and recurrent tumor. © 1999-2012 IEEE.

IEEE Transactions on Multimedia

Directive contrast based multimodal medical image fusion in NSCT domain

In this article, a novel logo watermarking scheme is proposed based on wavelet frame transform, singular value decomposition and automatic thresholding. The proposed scheme essentially rectifies the ambiguity problem in the SVD-based watermarking. The core idea is to randomly upscale the size of host image using reversible random extension transform followed by the embedding of logo watermark in the wavelet frame domain. After embedding, a verification phase is casted with the help of a binary watermark and toral automorphism. At the extraction end, the binary watermark is first extracted followed by the verification of watermarked image. The logo watermark is extracted if and only if the watermarked image is verified. The security, attack and comparative analysis confirm high security, efficiency and robustness of the proposed watermarking system. © 2013 ACM.