Tejendra Kumar Pun

Tejendra Kumar Pun
Saptagandaki Multiple Campus | SMC · Department of health

Bachelor of Education English

About

69
Publications
16,355
Reads
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1,737
Citations
Education
October 2016 - September 2020
Saptagandaki Multiple Campus
Field of study
  • English Education

Publications

Publications (69)
Article
Full-text available
« EyeWalker » est un projet qui a pour but de développer un appareil léger et compact s’adaptant facilement à n’importe quel déambulateur et alertant un/e utilisateur/trice avant qu’il/elle se trouve dans une situation dangereuse pouvant entraîner sa chute. Dans ce travail, nous traitons la détection de deux types de situations présentant un risque...
Article
Full-text available
Nowadays, there are many different types of mobility aids for elderly people. Nevertheless, these devices may lead to accidents, depending on the terrain where they are being used. In this paper, we present a robust ground change detector that will warn the user of potentially risky situations. Specifically, we propose a robust classification algor...
Article
Full-text available
With the increasing proportion of senior citizens, many mobility aid devices have been developed such as the rollator. However, under some circumstances, the latter may cause accidents. The EyeWalker project aims to develop a small and autonomous device for rollators to help elderly people, especially those with some degree of visual impairment, av...
Article
Full-text available
The See Color interface transforms a small portion of a colored video image into sound sources represented by spatialized musical instruments. Basically, the conversion of colors into sounds is achieved by quantization of the HSL color system. Our purpose is to provide visually impaired individuals with a capability of perception of the environment...
Conference Paper
Full-text available
In the context of vision substitution by the auditory channel several systems have been introduced. One such system that is presented here, See ColOr, is a dedicated interface part of a mobility aid for visually impaired people. It transforms a small portion of a colored video image into spatialized instrument sounds. In this work the purpose is to...
Article
This paper introduces an identification framework for random microstructures of material surfaces. These microstructures represent a kind of unique fingerprints that can be used to track and trace an item as well as for anti-counterfeiting. We first consider the architecture for mobile phone-based item identification and then introduce a practical...
Article
In this paper we address visual communications via print-and-scan channels from an information-theoretic point of view as communications with side information that targets quality enhancement of visual data at the output of this type of channels. The solution to this problem addresses important aspects of multimedia data processing and management....
Article
Full-text available
In this paper, we deal with the problem of authentication and tamper-proofing of text documents that can be distributed in electronic or printed forms. We advocate the combination of robust text hashing and text data-hiding technologies as an efficient solution to this problem. First, we consider the problem of text data-hiding in the scope of the...
Conference Paper
Full-text available
In this paper, we consider the problem of optimal self-embedding Laplacian data hiding for the state-dependent channels. In particular, we propose to decompose the Laplacian data using the paradigm of parallel source splitting. Experimental validation confirms the efficiency of the proposed approach
Conference Paper
In this paper, we address the analysis of the Costa setup under channel uncertainty. Since the Costa setup was entirely considered under the Gaussian assumptions about host and channel statistics, we assume that the channel is an additive white Gaussian noise (AWGN) with unknown variance defined on some interval. First, we solve the problem of aver...
Article
In this paper we considered the problem of performance improvement of known-host-state (quantization-based) watermarking methods undergo additive white Gaussian noise (AWGN) and uniform noise attacks. We question the optimality of uniform high rate quantizer based design of dither modulation and distortion compensate dither modulation methods from...
Article
Full-text available
In this paper, we propose a new theoretical framework for the data-hiding problem of digital and printed text documents. We explain how this problem can be seen as an instance of the well-known Gel'fand-Pinsker problem. The main idea for this interpretation is to consider a text character as a data structure consisting of multiple quantifiable feat...
Article
Full-text available
In data-hiding the issue of the achievable rate maximization is closely related to the problem of host interference cancellation. The optimal host interference cancellation relies on the knowledge of the host realization and the channel statistics (the additive white Gaussian noise (AWGN) variance) available at the encoder a priori to the transmiss...
Article
Full-text available
In this paper, we tackle the problem of performance improvement of quantization-based data-hiding in the middle-watermark-to-noise ratio (WNR) regime. The objective is to define the quantization-based framework that maximizes the performance of the known-host-state data-hiding in the middle-WNR taking into account the host probability density funct...
Article
In a data hiding communications scenario, geometrical attacks lead to a loss of reliable communications due to synchronization problems when the applied attack is unknown. In our previous work, information-theoretic analysis of this problem was performed for theoretic setups, i.e., when the length of communicated data sequences asymptotically appro...
Conference Paper
This work concerns the problem of asymmetric classification and provides the following contributions. First, it introduces the method of KDDA - a kernelized extension of the distance-based discriminant analysis technique that treats data asymmetrically and naturally accommodates indefinite kernels. Second, it demonstrates that KDDA and other asymme...
Conference Paper
Full-text available
Spread spectrum (SS) or known-host-statistics technique has shown the best performance in terms of both rate of reliable communications and bit error probability at the low watermark-to-noise ratio (WNR) regime. These results were obtained assuming that the host data follows an independent and identically distributed (i.i.d.) Gaussian distribution....
Article
In this paper a novel stochastic image model in the transform domain is presented and its performance in image denoising application is experimentally validated. The proposed model exploits local subband image statistics and is based on geometrical priors. Contrarily to models based on local correlations, or mixture models, the proposed model perfo...
Conference Paper
Full-text available
We present in this paper a novel statistical based focalized reconstruction method for the underdetermined EEG (electroencephalogram) inverse problem. The algorithm is based on the representation of non-Gaussian distributions as an infinite mixture of Gaussians (IMG) and relies on an iterative procedure consisting out of alternated variance estimat...
Conference Paper
Full-text available
Text documents, in electronic and hardcopy forms, are and will probably remain the most widely used kind of content in our digital age. The goal of this paper is to overview protocols for text data-hiding based "smart documents", achieving document self-authentication, self-recovery, self-annotation and automatic processing. We argue that document...
Conference Paper
Full-text available
A comparison of different bit-rate definitions used in the Brain-Computer Interface (BCI) community is proposed; assumptions underlying those definitions and their limitations are discussed. Capacity estimates using Wolpaw and Nykopp bit-rates are computed for various published BCIs. It appears that only Nykopp's bit-rate is coherent with channel c...
Article
Full-text available
In this paper, we extend a traditional robust data-hiding set- up with host state at the encoder to a case when a partial side information about host statistics is also available at the de- coder. We demonstrate that the knowledge of the host statis- tics at the decoder can relax the critical requirements of ran- dom binning-based methods concernin...
Article
Full-text available
In this paper, we tackle the problem of performance improvement of quantization-based data-hiding in the middle-watermark-to-noise ratio (WNR) regime. The objective is to define the quantization-based framework that maximizes the performance of the known-host-state data-hiding in the middle-WNR taking into account the host probability density funct...
Conference Paper
Full-text available
The surface Laplacian is known to be a theoretical reliable approximation of the cortical activity. Unfortunately, because of its high pass character and the relative low density of the EEG caps, the estimation of the Laplacian itself tends to be very sensitive to noise. We introduce a method based on vector field regularization through diffusion f...
Article
In this paper we address visual communications via printing channels from an information-theoretic point of view as communications with side information. The solution to this problem addresses important aspects of multimedia data processing, security and management, since printed documents are still the most common form of visual information repres...
Article
Full-text available
Periodical watermark embedding has been especially proposed to cope with geometrical attacks. Using a di- versity approach, this method allows to decrease the probability of error in the case of additive attacks. It is usually admitted that the worst additive attack con- sists in the addition of additive white Gaussian noise (AWGN). However, our th...
Conference Paper
Full-text available
In the scope of quantization-based watermarking techniques and additive attacks, there exists a common belief that the worst case attack (WCA) is given by additive white Gaussian noise (AWGN). Nevertheless, it has not been proved that the AWGN is indeed the WCA within the class of additive attacks against quantization-based watermarking. In this pa...
Conference Paper
Full-text available
In this paper we introduce and develop a framework for the data-hiding technologies that aim at resolving emerging problems of modern public networks. First, we emphasize the main open issues in public network security, quality of services control and secure communications. Secondly, we formulate digital data hiding as communications with side info...
Article
Digital watermarking appears today as an eecient mean of securing multimedia documents. Several application scenarios in the security of digital watermarking have been pointed out, each of them with diierent requirements. The three main identiÿed scenarios are: copyright protection, i.e. protecting ownership and usage rights; tamper prooÿng, aiming...
Article
This study implemented three different methods for presenting scientific graphs to visually impaired people: audition, kinesthetics, or a combination of the two. The results indicate that the combination of both audio and kinesthetic modalities can be a promising representation medium of common scientific graphs for people who are visually impaired...
Conference Paper
Full-text available
In this paper we consider the problem of joint capacity-security analysis of data hiding technologies from the communications point of view. First, we formulate data hiding as an optimal encoding problem for different operational regimes, that include both robust digital watermarking and steganography. This provides the corresponding estimation of...
Article
Digital image watermarking techniques for copyright protection have become increasingly robust. The best algorithms perform well against the now standard benchmark tests included in the Stirmark package. However the stirmark tests are limited since in general they do not properly model the watermarking process and consequently are limited in their...
Article
Full-text available
Invisible digital watermarks have been proposed as a method for discouraging illicit copying and distribution of copyright material. In recent years, it has been recognized that embedding information in a transform domain leads to more robust watermarks. A major difficulty in watermarking in a transform domain lies in the fact that constraints on t...
Conference Paper
Full-text available
This paper presents an efficient method for the estimation and recovering from nonlinear or local geometrical distortions, such as the random bending attack and restricted projective transforms. The distortions are modeled as a set of local affine transforms, the watermark being repeatedly allocated into small blocks in order to ensure its locality...
Article
Full-text available
Watermarking is a potential method for protection of ownership rights on digital audio, image and video data. Benchmarks are used to evaluate the performance of different watermarking algorithms. For image watermarking, the Stirmark package is the most popular benchmark, and the best current algorithms perform well against it. However, results obta...
Conference Paper
Full-text available
Benchmarking has always been a crucial problem in content-based image retrieval (CBIR).A key issue is the lack of a common access method to retrieval systems, such as SQL for relational databases. The Multimedia Retrieval Mark-up Language (MRML) solves this problem by standardizing access to CBIR systems (CBIRSs). Other difficult problems are also...
Article
We describe a projectively invariant representation of disjoint contour groups, which is suitable for shape-based retrieval from an image database. It consists of simultaneous polar reparametrization of multiple curves where an invariant point is used as the origin. For each ray orientation, a cross-ratio of its intersections with other curves is t...
Conference Paper
Full-text available
This paper describes a two-stage statistical approach supporting content-based search in image databases. The first stage performs correspondence analysis, a factor analysis method transforming image attributes into a reduced-size, uncorrelated factor space. The second stage performs ascendant hierarchical classification, an iterative clustering me...
Conference Paper
This project concerns the management of a multimedia database (text and image) of historical papers representing ancient watermarks. The current database contains roughly 3000 images of such watermarks; the system allows archival and retrieval by means of textual or morphological criteria. During the archival phase, textual description are stored,...
Article
this paper we show how images in a database can be provided with additional information allowing viewpoint invariant shape query. Viewpoint invariance allows to compensate for affine or projective distortions, and is achieved by the usage of invariant reference frames. Those frames serve as a canonical coordinate system, common for all shapes in th...
Article
The Potato Operation is a project belonging to the domain of agricultural robotics. It aims to automate pulp sampling of potatoes in order to detect viral diseases. The results of the analysis of these samples are used for the certification of potatoes marked out as seed. The difficulty of this problem lies in the high variability of natural object...
Article
The Potato Operation is a project belonging to the domain of agricultural robotics. It aims to automate pulp sampling of potatoes in order to detect viral diseases. The results of the analysis of these samples are used for the certification of potatoes marked out as seeds. The difficulty of this project lies in the high variability of natural objec...
Conference Paper
When computer vision algorithms are applied to autonomous robots, several dynamic aspects of perception must be taken into account. Among the most important ones is the capability to modify the image acquisition parameters, in order to perform ocular saccades, or to visually track moving objects. This ability is provided by the alerting and attenti...
Article
Photodensitometry is known to provide high spatial resolution and continuous measurement of optical density for the analysis of dental radiographs, whereas digitization allows powerful image manipulations but, when using conventional video cameras, gives less spatial resolution and fewer grey levels. The aim of this study was therefore to develop a...
Conference Paper
The potato operation is a project belonging to the domain of agricultural robotics, or agrotics. It aims to automate pulp sampling of potatoes in order to detect viral diseases. The difficulty of this problem lies in the high variability (shape, texture, colour) of natural objects. Three approaches have been studied, based on contour classification...
Article
High resolution two-dimensional gel electrophoresis is a very powerful biochemical tool for analysis of complex protein mixtures. In well defined situations, protein maps, obtained from tissue biopsies or biological fluids by this technique, can be automatically analyzed by computer. Some polypeptide patterns are the fingerprints of diseases. Apply...
Article
Application of image segmentation to biomedical research is now customary. Due to the existence of a rich heuristic knowledge, many users have no deep experience in this field. It is therefore necessary to integrate knowledge-based techniques with image segmentation operators. The purpose of our expert system is to guide users in image segmentation...
Article
A powerful data processing methodology for analysis and classification of two-dimensional gels is introduced. The approach is based on correspondence analysis (CA) and ascendant hierarchical classification (AHC), and significantly differs from the more classical principal-component decomposition. Starting with a series of gels, each having a large...
Article
Full-text available
Although two-dimensional (2-D) gel electrophoresis is one of the most powerful techniques for analyzing protein mixtures, its application in routine clinical laboratories is currently limited, because it is time-consuming, complex, and relatively expensive. Here we describe a method for automatically running and staining "high-resolution" mini 2-D...
Conference Paper
Full-text available
In this work, we consider the text data-hiding problem as a particular instance of the well-known Gel’fand-Pinsker problem [1]. The text, where some message m Î Mm \in \mathcal{M} is to be hidden, is represented by x and called cover text. Each component x i , i = 1, 2, ..., N, of x represents one character from this text. Here, we define a charac...
Article
Full-text available
The DVP project investigated the Quality of Service (QoS) requirements of broadcasters for several forms of distributed video production and run a series of trials of distributed virtual studios (studio on demand), distributed virtual reality, distributed musical rehearsals and distributed video editing and retrieval. The CUI of the University of G...
Article
Full-text available
In this paper we perform the capacity analysis of known- host-statitistics watermarking methods based on spread spec- trum (SS) under Additive Whight Gaussian noise (AWGN) attack. The reason of our research is based on the para- dox that being non-effective in theory SS-based practical watermarking systems outperform known-host-state meth- ods when...
Article
Full-text available
In this paper we introduce and develop a framework for visual data-hiding technologies that aim at resolving emerging problems of modern multimedia networking. First, we present the main open issues of multimedia security and se-cure communications. Secondly, we formulate multimedia data-hiding as commu-nications with side information and advocate...
Article
Cet article traite de trois problèmes intervenant lors de la reconnaissance d'objets 2D reposant sur des fonds très texturés: la présence de multiples objets de positions, tailles et orientations inconnues; le fond non uniforme qui génère des primitives irrelevantes pour la reconnaissance et finalement les processus de segmentation qui sont imparfa...

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