164 research outputs found
Proceedings of the second "international Traveling Workshop on Interactions between Sparse models and Technology" (iTWIST'14)
The implicit objective of the biennial "international - Traveling Workshop on
Interactions between Sparse models and Technology" (iTWIST) is to foster
collaboration between international scientific teams by disseminating ideas
through both specific oral/poster presentations and free discussions. For its
second edition, the iTWIST workshop took place in the medieval and picturesque
town of Namur in Belgium, from Wednesday August 27th till Friday August 29th,
2014. The workshop was conveniently located in "The Arsenal" building within
walking distance of both hotels and town center. iTWIST'14 has gathered about
70 international participants and has featured 9 invited talks, 10 oral
presentations, and 14 posters on the following themes, all related to the
theory, application and generalization of the "sparsity paradigm":
Sparsity-driven data sensing and processing; Union of low dimensional
subspaces; Beyond linear and convex inverse problem; Matrix/manifold/graph
sensing/processing; Blind inverse problems and dictionary learning; Sparsity
and computational neuroscience; Information theory, geometry and randomness;
Complexity/accuracy tradeoffs in numerical methods; Sparsity? What's next?;
Sparse machine learning and inference.Comment: 69 pages, 24 extended abstracts, iTWIST'14 website:
http://sites.google.com/site/itwist1
Unmanned aerial vehicle video-based target tracking algorithm Using sparse representation
Target tracking based on unmanned aerial vehicle
(UAV) video is a significant technique in intelligent urban
surveillance systems for smart city applications, such as smart
transportation, road traffic monitoring, inspection of stolen
vehicle, etc. In this paper, a vision-based target tracking algorithm
aiming at locating UAV-captured targets, like pedestrian and
vehicle, is proposed using sparse representation theory. First of all,
each target candidate is sparsely represented in the subspace
spanned by a joint dictionary. Then, the sparse representation
coefficient is further constrained by an L2 regularization based on
the temporal consistency. To cope with the partial occlusion
appearing in UAV videos, a Markov Random Field (MRF)-based
binary support vector with contiguous occlusion constraint is
introduced to our sparse representation model. For long-term
tracking, the particle filter framework along with a dynamic
template update scheme is designed. Both qualitative and
quantitative experiments implemented on visible (Vis) and
infrared (IR) UAV videos prove that the presented tracker can
achieve better performances in terms of precision rate and success
rate when compared with other state-of-the-art tracker
Information Extraction and Modeling from Remote Sensing Images: Application to the Enhancement of Digital Elevation Models
To deal with high complexity data such as remote sensing images presenting metric resolution over large areas, an innovative, fast and robust image processing system is presented.
The modeling of increasing level of information is used to extract, represent and link image features to semantic content.
The potential of the proposed techniques is demonstrated with an application to enhance and regularize digital elevation models based on information collected from RS images
The development of optical projection tomography instrumentation and its application to in vivo three dimensional imaging of zebrafish
OPT is a three dimensional (3D) imaging technique that can produce 3D reconstructions of
transparent samples, requiring only a widefield imaging system and sample rotation. OPT can
be readily applied to chemically cleared samples, or to live transparent organisms such as nematodes
or zebrafish. For preclinical imaging, there is a trade-off between optical accessibility and
biological relevance to humans. Adult Danio rerio (zebrafish) represent a promising compromise,
with greater homology to humans than smaller animals, and superior optical accessibility
than mice. However, their size and physiology present a number of imaging challenges including
non-negligible absorption and optical scattering, and limited time for image data acquisition if
the fish are to be recovered for longitudinal studies. A key goal of this PhD thesis research was
to develop OPT to address these challenges and improve in vivo imaging capabilities for this
model organism.
This thesis builds on previous work at Imperial where angularly multiplexed OPT using
compressed sensing was developed and applied to in vivo imaging of a cancer-burdened adult
zebrafish, with a sufficiently short OPT data acquisition time to allow recovery of the fish after
anaesthesia. The previous cross-sectional study of this work was extended to a longitudinal
study of cancer progression that I undertook. The volume and quality of data acquired in
the longitudinal study presented a number of data processing challenges, which I addressed
with improved automation of the data processing pipeline and with the demonstration that
convolutional neural networks (CNN) could replace the iterative compressed sensing algorithm
previously used to suppress artifacts when reconstructing undersampled OPT data sets.
To address the issue of high attenuation through the centre of an adult zebrafish, I developed
conformal-high-dynamic-range (C-HDR) OPT and demonstrated that it could provide sufficient
dynamic range for brightfield imaging of such optically thick samples, noting that transmitted
light images can provide anatomical context for fluorescence image data.
To reduce the impact of optical scattering in OPT, I developed a parallelised quasi-confocal
version of OPT called slice-illuminated OPT (slice-OPT) to reject scattered photons and demonstrated
this with live zebrafish. To enable 3D imaging with short wave infrared (SWIR) light,
without the requirement of an expensive Ge or InGaAs camera, I implemented a single pixel
camera and demonstrated single-pixel OPT (SP-OPT) for the first time.Open Acces
A comprehensive approach for the efficient acquisition and processing of hyperspectral images and sequence
Programa Oficial de Doctorado en Computación. 5009P01[Abstract]
Despite the scientific and technological developments achieved during the last
two decades in the hyperspectral field, some methodological, operational and
conceptual issues have restricted the progress, promotion and popular dissemination
of this technology. These shortcomings include the specialized knowledge
required for the acquisition of hyperspectral images, the shortage of publicly accessible
hyperspectral image repositories with reliable ground truth images or
the lack of methodologies that allow for the adaptation of algorithms to particular
user or application processing needs.
The work presented here has the objective of contributing to the hyperspectral
field with procedures for the automatic acquisition of hyperspectral scenes,
including the hardware adaptation of our own imagers and the development
of methods for the calibration and correction of the hyperspectral datacubes,
the creation of a publicly available hyperspectral repository of well categorized
and labeled images and the design and implementation of novel computational
intelligence based processing techniques that solve typical issues related to the
segmentation and denoising of hyperspectral images as well as sequences of them
taking into account their temporal evolution.[Resumen]
A pesar de los desarrollos tecnológicos y científicos logrados en el campo hiperespectral
durante las dos últimas décadas, alg\mas limitaciones de tipo metodológico,
operacional y conceptual han restringido el progreso, difusión y popularización
de esta tecnología, entre ellas, el conocimiento especializado requerido
en la adquisición de imágenes hiperespectrales, la carencia de repositorios de
imágenes hiperespectrales con etiquetados fiables y de acceso público o la falta
de metodologías que posibiliten la adaptación de algoritmos a usuarios o necesidades
de procesamiento concretas.
Este trabajo doctoral tiene el objetivo de contribuir al campo hiperespectral
con procedimientos para la adquisición automática de escenas hiperespectrales,
incluyendo la adaptación hardware de cámaras hiperespectrales propias
y el desarrollo de métodos para la calibración y corrección de cubos de datos
hiperespectrales; la creación de un repositorio hiperespectral de acceso público
con imágenes categorizadas y con verdades de terreno fiables; y el diseño e
implementación de técnicas de procesamiento basadas en inteligencia computacional
para la resolución de problemas típicamente relacionados con las tareas
de segmentación y eliminación de ruido en imágenes estáticas y secuencias de
imágenes hiperespectrales teniendo en consideración su evolución temporal.[Resumo]
A pesar dos desenvolvementos tecnolóxicos e científicos logrados no campo
hiperespectral durante as dúas últimas décadas, algunhas lirrútacións de tipo
metodolóxico¡ operacional e conceptual restrinxiron o progreso) difusión e popularización
desta tecnoloxía, entre elas, o coñecemento especializado requirido
na adquisición de imaxes hiperespectrales¡ a carencia de repositorios de irnaxes
hiperespectrales con etiquetaxes fiables e de acceso público ou a falta de metodoloxías
que posibiliten a adaptación de algoritmos a usuarios ou necesidades de
procesamento concretas.
Este traballo doutoral ten o obxectívo de contribuir ao campo hiperespectral
con procedementos para a adquisición automática de eicenas hiperespectrais,
incluíndo a adaptación hardware de cámaras hiperespectrales propias e o desenvolvemento
de métodos para a calibración e corrección de cubos de datos hiperespectrais;
a creación dun repositorio hiperespectral de acceso público con imaxes
categorizadas e con verdades de terreo fiables; e o deseño e implementación de
técnicas de procesamento baseadas en intelixencia computacional para a resolución
de problemas tipicamente relacionado~ coas tarefas de segmentación e
eliminación de ruído en imaxes estáticas e secuencias de imaxes hiperespectrai~
tendo en consideración a súa evolución temporal
Methods for Improving Signal to Noise Ratio in Raman Spectra
Raman microspectroscopy is an optoelectronic technique based on the inelastic scattering of light. This
technique has been demonstrated to have potential to identify different materials based on subtle differences
in the Raman spectral profile using various multivariate statistical classification tools. However,
Raman scattering is an inherently weak process. Low photon counts coupled with non-ideal collection efficiencies
means that Raman spectroscopy is vulnerable to noise. This makes system optimisations, as well
as efficient and reliable noise removal, a necessity in sensitive applications such as chemical classification
or diagnostics. Provided in this thesis are software and experimental methodologies to evaluate system
performance, predict system performance under various conditions, and to identify the optimal system
configuration/set-up in order to achieve the highest possible signal to noise ratio. Modelling methodologies
presented in this thesis allow the user to systematically evaluate minimum acquisition times, optimise
camera read-out modes, and predict system behaviour with alternative optical elements in order to maximise
signal to noise ratio. The denosing algorithms presented in this thesis have been shown to provide
superior signal to noise ratio when compared with their traditional counterparts. When compared with the
double acquisition method, the proposed cosmic ray removal algorithm resulted in a 10% improvement. An
algorithm that enhances Savitzky-Golay smoothing with maximum likelihood estimation produced spectra
with up to double the signal to noise ratio when compared to the raw spectra and consistently outperformed
the algorithms it was compared to. The use of reflective substrates is also investigated and was shown to
approximately triple the collected Raman scatter when compared with transparent substrates. By utilising
the methodologies detailed in this thesis it is possible to improve the efficiency of the Raman system in
question
Vision Sensors and Edge Detection
Vision Sensors and Edge Detection book reflects a selection of recent developments within the area of vision sensors and edge detection. There are two sections in this book. The first section presents vision sensors with applications to panoramic vision sensors, wireless vision sensors, and automated vision sensor inspection, and the second one shows image processing techniques, such as, image measurements, image transformations, filtering, and parallel computing
Visual analysis and synthesis with physically grounded constraints
The past decade has witnessed remarkable progress in image-based, data-driven vision and graphics. However, existing approaches often treat the images as pure 2D signals and not as a 2D projection of the physical 3D world. As a result, a lot of training examples are required to cover sufficiently diverse appearances and inevitably suffer from limited generalization capability. In this thesis, I propose "inference-by-composition" approaches to overcome these limitations by modeling and interpreting visual signals in terms of physical surface, object, and scene. I show how we can incorporate physically grounded constraints such as scene-specific geometry in a non-parametric optimization framework for (1) revealing the missing parts of an image due to removal of a foreground or background element, (2) recovering high spatial frequency details that are not resolvable in low-resolution observations. I then extend the framework from 2D images to handle spatio-temporal visual data (videos). I demonstrate that we can convincingly fill spatio-temporal holes in a temporally coherent fashion by jointly reconstructing the appearance and motion. Compared to existing approaches, our technique can synthesize physically plausible contents even in challenging videos. For visual analysis, I apply stereo camera constraints for discovering multiple approximately linear structures in extremely noisy videos with an ecological application to bird migration monitoring at night. The resulting algorithms are simple and intuitive while achieving state-of-the-art performance without the need of training on an exhaustive set of visual examples
Reports on industrial information technology. Vol. 12
The 12th volume of Reports on Industrial Information Technology presents some selected results of research achieved at the Institute of Industrial Information Technology during the last two years.These results have contributed to many cooperative projects with partners from academia and industry and cover current research interests including signal and image processing, pattern recognition, distributed systems, powerline communications, automotive applications, and robotics
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