2,869 research outputs found
Frequency-modulated continuous-wave LiDAR compressive depth-mapping
We present an inexpensive architecture for converting a frequency-modulated
continuous-wave LiDAR system into a compressive-sensing based depth-mapping
camera. Instead of raster scanning to obtain depth-maps, compressive sensing is
used to significantly reduce the number of measurements. Ideally, our approach
requires two difference detectors. % but can operate with only one at the cost
of doubling the number of measurments. Due to the large flux entering the
detectors, the signal amplification from heterodyne detection, and the effects
of background subtraction from compressive sensing, the system can obtain
higher signal-to-noise ratios over detector-array based schemes while scanning
a scene faster than is possible through raster-scanning. %Moreover, we show how
a single total-variation minimization and two fast least-squares minimizations,
instead of a single complex nonlinear minimization, can efficiently recover
high-resolution depth-maps with minimal computational overhead. Moreover, by
efficiently storing only data points from measurements of an
pixel scene, we can easily extract depths by solving only two linear equations
with efficient convex-optimization methods
Synthetic Aperture Radar (SAR) data processing
The available and optimal methods for generating SAR imagery for NASA applications were identified. The SAR image quality and data processing requirements associated with these applications were studied. Mathematical operations and algorithms required to process sensor data into SAR imagery were defined. The architecture of SAR image formation processors was discussed, and technology necessary to implement the SAR data processors used in both general purpose and dedicated imaging systems was addressed
A Study on Visually Encrypted Images for Rights Protection and Authentication
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Spread spectrum-based video watermarking algorithms for copyright protection
Merged with duplicate record 10026.1/2263 on 14.03.2017 by CS (TIS)Digital technologies know an unprecedented expansion in the last years. The consumer can
now benefit from hardware and software which was considered state-of-the-art several years
ago. The advantages offered by the digital technologies are major but the same digital
technology opens the door for unlimited piracy. Copying an analogue VCR tape was certainly
possible and relatively easy, in spite of various forms of protection, but due to the analogue
environment, the subsequent copies had an inherent loss in quality. This was a natural way of
limiting the multiple copying of a video material. With digital technology, this barrier
disappears, being possible to make as many copies as desired, without any loss in quality
whatsoever. Digital watermarking is one of the best available tools for fighting this threat.
The aim of the present work was to develop a digital watermarking system compliant with the
recommendations drawn by the EBU, for video broadcast monitoring. Since the watermark
can be inserted in either spatial domain or transform domain, this aspect was investigated and
led to the conclusion that wavelet transform is one of the best solutions available. Since
watermarking is not an easy task, especially considering the robustness under various attacks
several techniques were employed in order to increase the capacity/robustness of the system:
spread-spectrum and modulation techniques to cast the watermark, powerful error correction
to protect the mark, human visual models to insert a robust mark and to ensure its invisibility.
The combination of these methods led to a major improvement, but yet the system wasn't
robust to several important geometrical attacks. In order to achieve this last milestone, the
system uses two distinct watermarks: a spatial domain reference watermark and the main
watermark embedded in the wavelet domain. By using this reference watermark and techniques
specific to image registration, the system is able to determine the parameters of the attack and
revert it. Once the attack was reverted, the main watermark is recovered. The final result is a
high capacity, blind DWr-based video watermarking system, robust to a wide range of attacks.BBC Research & Developmen
Towards visualization and searching :a dual-purpose video coding approach
In modern video applications, the role of the decoded video is much more than filling a screen for visualization. To offer powerful video-enabled applications, it is increasingly critical not only to visualize the decoded video but also to provide efficient searching capabilities for similar content. Video surveillance and personal communication applications are critical examples of these dual visualization and searching requirements. However, current video coding solutions are strongly biased towards the visualization needs. In this context, the goal of this work is to propose a dual-purpose video coding solution targeting both visualization and searching needs by adopting a hybrid coding framework where the usual pixel-based coding approach is combined with a novel feature-based coding approach. In this novel dual-purpose video coding solution, some frames are coded using a set of keypoint matches, which not only allow decoding for visualization, but also provide the decoder valuable feature-related information, extracted at the encoder from the original frames, instrumental for efficient searching. The proposed solution is based on a flexible joint Lagrangian optimization framework where pixel-based and feature-based processing are combined to find the most appropriate trade-off between the visualization and searching performances. Extensive experimental results for the assessment of the proposed dual-purpose video coding solution under meaningful test conditions are presented. The results show the flexibility of the proposed coding solution to achieve different optimization trade-offs, notably competitive performance regarding the state-of-the-art HEVC standard both in terms of visualization and searching performance.Em modernas aplicaƧƵes de vĆdeo, o papel do vĆdeo decodificado Ć© muito mais que simplesmente preencher uma tela para visualizaĆ§Ć£o. Para oferecer aplicaƧƵes mais poderosas por meio de sinais de vĆdeo,Ć© cada vez mais crĆtico nĆ£o apenas considerar a qualidade do conteĆŗdo objetivando sua visualizaĆ§Ć£o, mas tambĆ©m possibilitar meios de realizar busca por conteĆŗdos semelhantes. Requisitos de visualizaĆ§Ć£o e de busca sĆ£o considerados, por exemplo, em modernas aplicaƧƵes de vĆdeo vigilĆ¢ncia e comunicaƧƵes pessoais. No entanto, as atuais soluƧƵes de codificaĆ§Ć£o de vĆdeo sĆ£o fortemente voltadas aos requisitos de visualizaĆ§Ć£o. Nesse contexto, o objetivo deste trabalho Ć© propor uma soluĆ§Ć£o de codificaĆ§Ć£o de vĆdeo de propĆ³sito duplo, objetivando tanto requisitos de visualizaĆ§Ć£o quanto de busca. Para isso, Ć© proposto um arcabouƧo de codificaĆ§Ć£o em que a abordagem usual de codificaĆ§Ć£o de pixels Ć© combinada com uma nova abordagem de codificaĆ§Ć£o baseada em features visuais. Nessa soluĆ§Ć£o, alguns quadros sĆ£o codificados usando um conjunto de pares de keypoints casados, possibilitando nĆ£o apenas visualizaĆ§Ć£o, mas tambĆ©m provendo ao decodificador valiosas informaƧƵes de features visuais, extraĆdas no codificador a partir do conteĆŗdo original, que sĆ£o instrumentais em aplicaƧƵes de busca. A soluĆ§Ć£o proposta emprega um esquema flexĆvel de otimizaĆ§Ć£o Lagrangiana onde o processamento baseado em pixel Ć© combinado com o processamento baseado em features visuais objetivando encontrar um compromisso adequado entre os desempenhos de visualizaĆ§Ć£o e de busca. Os resultados experimentais mostram a flexibilidade da soluĆ§Ć£o proposta em alcanƧar diferentes compromissos de otimizaĆ§Ć£o, nomeadamente desempenho competitivo em relaĆ§Ć£o ao padrĆ£o HEVC tanto em termos de visualizaĆ§Ć£o quanto de busca
A Survey on Biometrics based Digital Image Watermarking Techniques and Applications
The improvements in Internet technologies and growing demands on online multimedia businesses have made digital copyrighting as a major challenge for businesses that are associated with online content distribution via diverse business models including pay-per-view subscription trading etc Copyright protection and the evidence for rightful ownership are major issues associated with the distribution of any digital images Digital watermarking is a probable solution for digital content owners that offer security to the digital content In recent years digital watermarking plays a vital role in providing the apposite solution and numerous researches have been carried out In this paper an extensive review of the prevailing literature related to the Bio- watermarking is presented together with classification by utilizing an assortment of techniques In addition a terse introduction about the Digital Watermarking is presented to get acquainted with the vital information on the subject of Digital Watermarkin
Advanced Television Research Program
Contains reports on ten research projects.National Science Foundation Grant MIP 87-14969National Science Foundation FellowshipAdvanced Television Research ProgramAT&T Bell Laboratories Doctoral Support ProgramKodak FellowshipU.S. Air Force - Electronic Systems Division Contract F1 9628-89-K-004
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