375 research outputs found
Real-time multiframe blind deconvolution of solar images
The quality of images of the Sun obtained from the ground are severely
limited by the perturbing effect of the turbulent Earth's atmosphere. The
post-facto correction of the images to compensate for the presence of the
atmosphere require the combination of high-order adaptive optics techniques,
fast measurements to freeze the turbulent atmosphere and very time consuming
blind deconvolution algorithms. Under mild seeing conditions, blind
deconvolution algorithms can produce images of astonishing quality. They can be
very competitive with those obtained from space, with the huge advantage of the
flexibility of the instrumentation thanks to the direct access to the
telescope. In this contribution we leverage deep learning techniques to
significantly accelerate the blind deconvolution process and produce corrected
images at a peak rate of ~100 images per second. We present two different
architectures that produce excellent image corrections with noise suppression
while maintaining the photometric properties of the images. As a consequence,
polarimetric signals can be obtained with standard polarimetric modulation
without any significant artifact. With the expected improvements in computer
hardware and algorithms, we anticipate that on-site real-time correction of
solar images will be possible in the near future.Comment: 16 pages, 12 figures, accepted for publication in A&
Invariant Scattering Transform for Medical Imaging
Invariant scattering transform introduces new area of research that merges
the signal processing with deep learning for computer vision. Nowadays, Deep
Learning algorithms are able to solve a variety of problems in medical sector.
Medical images are used to detect diseases brain cancer or tumor, Alzheimer's
disease, breast cancer, Parkinson's disease and many others. During pandemic
back in 2020, machine learning and deep learning has played a critical role to
detect COVID-19 which included mutation analysis, prediction, diagnosis and
decision making. Medical images like X-ray, MRI known as magnetic resonance
imaging, CT scans are used for detecting diseases. There is another method in
deep learning for medical imaging which is scattering transform. It builds
useful signal representation for image classification. It is a wavelet
technique; which is impactful for medical image classification problems. This
research article discusses scattering transform as the efficient system for
medical image analysis where it's figured by scattering the signal information
implemented in a deep convolutional network. A step by step case study is
manifested at this research work.Comment: 11 pages, 8 figures and 1 tabl
Augmented breast tumor classification by perfusion analysis
Magnetic resonance and computed tomography imaging aid in the diagnosis and analysis of pathologic conditions. Blood flow, or perfusion, through a region of tissue can be computed from a time series of contrast-enhanced images. Perfusion is an important set of physiological parameters that reflect angiogenesis. In cancer, heightened angiogenesis is a key process in the growth and spread of tumorous masses. An automatic classification technique using recovered perfusion may prove to be a highly accurate diagnostic tool. Such a classification system would supplement existing histopathological tests, and help physicians to choose the most optimal treatment protocol. Perfusion is obtained through deconvolution of signal intensity series and a pharmacokinetic model. However, many computational problems complicate the accurate-consistent recovery of perfusion. The high time-resolution acquisition of images decreases signal-to-noise, producing poor deconvolution solutions. The delivery of contrast agent as a function of time must also be determined or sampled before deconvolution can proceed. Some regions of the body, such as the brain, provide a nearby artery to serve as this arterial input function. Poor estimates can lead to an over or under estimation of perfusion. Breast tissue is an example of one tissue region where a clearly defined artery is not present. This proposes a new method of using recovered perfusion and spatial information in an automated classifier. This classifier grades suspected lesions as benign or malignant. This method can be integrated into a computer-aided diagnostic system to enhance the value of medical imagery
Video event detection and visual data pro cessing for multimedia applications
Cette thĂšse (i) dĂ©crit une procĂ©dure automatique pour estimer la condition d'arrĂȘt des mĂ©thodes de dĂ©convolution itĂ©ratives basĂ©es sur un critĂšre d'orthogonalitĂ© du signal estimĂ© et de son gradient Ă une itĂ©ration donnĂ©e; (ii) prĂ©sente une mĂ©thode qui dĂ©compose l'image en une partie gĂ©omĂ©trique (ou "cartoon") et une partie "texture" en utilisation une estimation de paramĂštre et une condition d'arrĂȘt basĂ©es sur la diffusion anisotropique avec orthogonalitĂ©, en utilisant le fait que ces deux composantes. "cartoon" et "texture", doivent ĂȘtre indĂ©pendantes; (iii) dĂ©crit une mĂ©thode pour extraire d'une sĂ©quence vidĂ©o obtenue Ă partir de camĂ©ra portable les objets de premier plan en mouvement. Cette mĂ©thode augmente la compensation de mouvement de la camĂ©ra par une nouvelle estimation basĂ©e noyau de la fonction de probabilitĂ© de densitĂ© des pixels d'arriĂšre-plan. Les mĂ©thodes prĂ©sentĂ©es ont Ă©tĂ© testĂ©es et comparĂ©es aux algorithmes de l'Ă©tat de l'art.This dissertation (i) describes an automatic procedure for estimating the stopping condition of non-regularized iterative deconvolution methods based on an orthogonality criterion of the estimated signal and its gradient at a given iteration; (ii) presents a decomposition method that splits the image into geometric (or cartoon) and texture parts using anisotropic diffusion with orthogonality based parameter estimation and stopping condition, utilizing the theory that the cartoon and the texture components of an image should be independent of each other; (iii) describes a method for moving foreground object extraction in sequences taken by wearable camera, with strong motion, where the camera motion compensated frame differencing is enhanced with a novel kernel-based estimation of the probability density function of the background pixels. The presented methods have been thoroughly tested and compared to other similar algorithms from the state-of-the-art.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF
Neuropathy Classification of Corneal Nerve Images Using Artificial Intelligence
Nerve variations in the human cornea have been associated with alterations in
the neuropathy state of a patient suffering from chronic diseases. For some diseases,
such as diabetes, detection of neuropathy prior to visible symptoms is important,
whereas for others, such as multiple sclerosis, early prediction of disease worsening is
crucial. As current methods fail to provide early diagnosis of neuropathy, in vivo
corneal confocal microscopy enables very early insight into the nerve damage by
illuminating and magnifying the human cornea. This non-invasive method captures a
sequence of images from the corneal sub-basal nerve plexus. Current practices of
manual nerve tracing and classification impede the advancement of medical research in
this domain. Since corneal nerve analysis for neuropathy is in its initial stages, there is
a dire need for process automation.
To address this limitation, we seek to automate the two stages of this process:
nerve segmentation and neuropathy classification of images. For nerve segmentation,
we compare the performance of two existing solutions on multiple datasets to select the
appropriate method and proceed to the classification stage. Consequently, we approach
neuropathy classification of the images through artificial intelligence using Adaptive
Neuro-Fuzzy Inference System, Support Vector Machines, NaĂŻve Bayes and k-nearest
neighbors. We further compare the performance of machine learning classifiers with
deep learning. We ascertained that nerve segmentation using convolutional neural networks provided a significant improvement in sensitivity and false negative rate by
at least 5% over the state-of-the-art software. For classification, ANFIS yielded the best
classification accuracy of 93.7% compared to other classifiers. Furthermore, for this
problem, machine learning approaches performed better in terms of classification
accuracy than deep learning
Combining ICA Representations for Recognizing Faces
Independent Component Analysis (ICA) is a generalization of Principal Component Analysis (PCA), and it looks for components that are both statistically independent and non-Gaussian. ICA is sensitive to high-order statistic and it expected to outperform PCA in finding better basis images. Moreover, with face recognition, high-order relationships among pixels may have more important information than those of pairwise relationships on which base images found by PCA depend. Two different representations can be applied by ICA; ICA architecture I and ICA architecture II. A new classifier that combines the two ICA architectures is proposed for face recognition. By the new classifier, the similarity measure vector was employed in which the similarity measure vectors for both ICA representations were resorted in descending order and then integrated by merging the corresponding values of each vector. The new classifier was performed on face images in the AR Face Database. Cumulative Match Characteristic was taken as a measure for evaluating the performance of the new classifier with illumination variation, expression, and Occlusion. The proposed classifier outperforms both ICA architectures in all cases especially in later ranks
Superresolution fluorescence microscopy with structured illumination
The resolution of a conventional fluorescence microscope image is diffraction limited which achieves a spatial resolution of 200nm lateral and 500nm axial. Recently, many superresolution fluorescence microscopy techniques have been developed which allow the observation of many biological structures beyond the diffraction limit. Structured illumination microscopy (SIM) is one of them. The principle of SIM is based on using a harmonic light grid which down modulates the high spatial frequencies of the sample into the observable region of the microscope. The resolution enhancement is highly dependent on the reconstruction technique, which restores the high spatial frequencies of the sample to their original position. Common SIM reconstructions require the perfect knowledge of the illumination pattern. However, to perfectly control the harmonic illumination patterns on the sample plane is not easy in experimental implementations and this makes the experimental setup very technical. Reconstructing SIM images assuming the perfect knowledge of the illumination intensity patterns may, therefore, introduce artifacts on the estimated sample due to the misalignment of the grid that can occur during experimental acquisitions. To tackle this drawback of SIM, in this these, we have developed blind-SIM reconstruction strategies which are independent of the illumination patterns. Using the 3D blind-SIM reconstruction strategies we extended the harmonic SIM to speckle illumination microscopy which uses random unknown speckle patterns that need no control, unlike the harmonic grid patterns. For harmonic-SIM images, since incorporating some information about illumination patterns is valuable, we have developed a 3D positive filtered blind-SIM reconstruction which confines the iterative estimation of the illuminations in the vicinity of the Fourier peaks (using carefully designed Fourier filter masks) in the Fourier space. Using blind-SIM reconstruction techniques a lateral resolution of about 100nm and axial resolution of about 200nm is obtained in both speckle and harmonic SIM. In addition, to reduce the out-of-focus problem in widefield images, a simple computational technique which is based on reconstructing 2D data with 3D PSF is developed based on blind-SIM reconstruction. Moreover, to combine the functionalities of SIM and light sheet microscopy, as a proof of concept, we have developed a simple microscope setup which produces a structured light sheet illumination pattern.La microscopie de fluorescence optique est lâun des outils les plus puissants pour Ă©tudier les structures cellulaires et molĂ©culaires au niveau subcellulaire. La rĂ©solution dâune image de microscope conventionnel Ă fluorescence est limitĂ©e par la diffraction, ce qui permet dâobtenir une
rĂ©solution spatiale latĂ©rale de 200nm et axiale de 500nm. RĂ©cemment, de nombreuses techniques de microscopie de fluorescence de super-rĂ©solution ont Ă©tĂ© dĂ©veloppĂ©es pour permettre dâobserver de
nombreuses structures biologiques au-delĂ de la limite de diffraction. La microscopie dâillumination structurĂ©e (SIM) est lâune de ces technologies. Le principe de la SIM est basĂ© sur lâutilisation dâune grille de lumiĂšre harmonique qui permet de translater les hautes frĂ©quences spatiales de lâĂ©chantillon vers la rĂ©gion dâobservation du microscope. LâamĂ©lioration de la rĂ©solution de cette technologie de microscopie dĂ©pend fortement de la technique de reconstruction, qui rĂ©tablit les hautes frĂ©quences
spatiales de lâĂ©chantillon dans leur position dâorigine. Les mĂ©thodes classiques de reconstruction SIM nĂ©cessitent une connaissance parfaite de lâillumination de lâĂ©chantillon. Cependant, lâimplĂ©mentation dâun contrĂŽle parfait de lâillumination harmonique sur le plan de lâĂ©chantillon
nâest pas facile expĂ©rimentalement et il prĂ©sente un grand dĂ©fi. LâhypothĂšse de la connaissance parfaite de lâintensitĂ© de la lumiĂšre illuminant lâĂ©chantillon en SIM peut donc introduire des artefacts
sur lâimage reconstruite de lâĂ©chantillon, Ă cause des erreurs dâalignement de la grille qui peuvent se prĂ©senter lors de lâacquisition expĂ©rimentale. Afin de surmonter ce dĂ©fi, nous avons dĂ©veloppĂ© dans cette thĂšse des stratĂ©gies de reconstruction «aveugle» qui sont indĂ©pendantes de
dâillumination. Ă lâaide de ces stratĂ©gies de reconstruction dites «blind-SIM», nous avons Ă©tendu la SIM harmonique pour lâappliquer aux cas de «SIM-speckle» qui utilisent des illuminations alĂ©atoires et inconnues qui contrairement Ă lâillumination harmonique, ne nĂ©cessitent pas de controle.
Comme il est utile de rĂ©cupĂ©rer des informations sur lâillumination en SIM harmonique, nous avons dĂ©veloppĂ© une reconstruction blind-SIM tridimensionnel et filtrĂ©e qui confine lâestimation itĂ©rative des illuminations au voisinage des pics dans lâespace de Fourier, en utilisant des masques de filtre de Fourier soigneusement conçus. En utilisant des techniques de reconstruction blind-SIM, une rĂ©solution latĂ©rale dâenviron 100 nm et une rĂ©solution axiale dâenviron 200 nm sont obtenues, Ă la fois en SIM harmonique et en SIM speckle. En outre, pour rĂ©duire le problĂšme de focalisation dans les images de champ large, une technique de calcul simple qui repose sur la reconstruction bidimensionnel de donnĂ©es Ă partir de PSF tridimensionnel est dĂ©veloppĂ©e. En outre, afin de combiner
à la fois les fonctionnalités de la SIM et de la microscopie å nappe de lumiÚre, en tant que preuve de concept, nous avons développé une configuration de microscope simple qui produit une nappe de lumiÚre structuré
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