Multiplicative Multiresolution Decomposition for Lossless Volumetric Medical Images Compression

With the emergence of medical imaging, the compression of volumetric medical images is essential. For this purpose, we propose a novel Multiplicative Multiresolution Decomposition (MMD) wavelet coding scheme for lossless compression of volumetric medical images. The MMD is used in speckle reduction technique but offers some proprieties which can be exploited in compression. Thus, as the wavelet transform the MMD provides a hierarchical representation and offers a possibility to realize lossless compression. We integrate in proposed scheme an inter slice filter based on wavelet transform and motion compensation to reduce data energy efficiently. We compare lossless results of classical wavelet coders such as 3D SPIHT and JP3D to the proposed scheme. This scheme incorporates MMD in lossless compression technique by applying MMD/wavelet or MMD transform to each slice, after inter slice filter is employed and the resulting sub-bands are coded by the 3D zero-tree algorithm SPIHT. Lossless experimental results show that the proposed scheme with the MMD can achieve lowest bit rates compared to 3D SPIHT and JP3D

Compression orientée restauration des images bruitées : application aux images échographiques

The medical diagnosis is strongly based on different medical imaging modalities. Consequently,the amount of digital image data to be stored or transmitted is huge. Hence,efficient and low-complexity compression becomes necessary. Medical image compression"intuitively" requires ensuring the quality of the diagnostic image while reducingthe bit rate. Regarding the modalities, ultrasound is one of the most widely used one.However, it has a drawback of visual quality caused by the speckle noise. This workaims to achieve speckle noise reduction together with lossy compression in ultrasoundmedical images, where the losses are mainly the undesirable speckle noise. Furthermore,the proposed compression scheme is efficiently applied to Magnetic ResonanceImages(MRI).In this thesis we propose three main contributions: a multi-output filter for specklereduction of medical ultrasound images, an image quality metric for medical context(ultrasound and MRI) and a scheme of compression for medical images. We perform astudy on the usability of opinion-unaware no-reference natural image quality metrics inthe context of medical images: filtered ultrasound and compressed Magnetic ResonanceImages (MRI), as result of the study we propose a metric adapted to medical images.Then, we propose a multi-output speckle reduction filter based on MMD (MOF-MMD),which makes it possible to obtain three filtered images that help the radiologist’s diagnosticneeds. Indeed, the diagnostic task is based on different characteristics of theimage. Since the end-user of the medical images is the radiologist, we believe that it ismore reasonable to evaluate the algorithm using human observers. Thus, we conducta subjective experiment involving three radiologists with different years of experience.The correlations between the subjective scores and the objective metrics outputs andthe impact of the radiologists years of experience are presented and analyzed. The lastcontribution consists on developing a lossy coding scheme based on the MMD appliedto ultrasound and MR Images.Le diagnostic médical est fortement basé sur différentes modalités d’imagerie médicale.En conséquence, la quantité de données d’images numériques à stocker ou à transmettreest considérable. Il devient nécessaire de développer des solutions de compressionefficace et peu complexe. La compression d’images médicales "intuitivement " exiged’assurer une qualité de l’image diagnostique qui n’engendre pas de risques d’erreur.Par ailleurs, l’échographie est l’une des modalités les plus utilisées. Cependant, elleprésente un inconvénient en terme de qualité visuelle causé par le bruit de speckle. Cetravail vise à réduire le bruit de speckle tout en effectuant une compression avec pertesdes images échographiques. Aussi, le schéma de compression proposé a été appliquéà une seconde modalité, l’imagerie par résonance magnétique (IRM). En effet l’IRMest une modalité gourmande en termes de capacité de stockage. Durant cette thèse,nous avons proposé trois contributions principales : un filtre à sorties multiples pourla réduction du speckle des images d’échographie médicale, une mesure de la qualitéd’image pour l’imagerie médicale (échographie et IRM) et un schéma de compressionpour les images médicales

Interfacial stress field generate by a biperiodic hexagonal network of misfit dislocations in a thin bicristal InAs/(111)GaAs

The elastic interactions generated by the presence of a biperiodic network, more precisely hexagonal, of misfit dislocations in the interfacing of a thin bicristal have been simulated numerically while considering an anisotropic elasticity for each crystal. The representation of the normal equi-stress near the dislocation segments and near of the triple node of hexagonal cell permits to detect the stress concentration zone du to elastic field for InAs/(111)GaAs system, because, in the category of semiconductors, this is an ideal system which exhibit the presence of edge dislocations type parallels to the free surfaces by S.T.M.[1].<br><br>Las interacciones elásticas generadas por la presencia de una red biperiódica, de dislocaciones en la interfase de un bicristal han sido simuladas numéricamente, considerando elasticidad anisotropa para cada cristal. La representación de las tensiones próximas a las dislocaciones y del nodo triple de la celda hexagonal, permite detectar la zona de concentración de tensiones debido al campo elástico para el sistema InAS/(111) GaAS, ya que, en los semiconductores, éste es un sistema ideal que muestra la presencia de dislocaciones paralelas a las superficies libres por S.T.M.[1]

Comparative study of the methodologies used for subjective medical image quality assessment

International audienceHealthcare professionals have been increasingly viewing medical images and videos in their routine clinical practice, and this in a wide variety of environments. Both the perception and interpretation of medical visual information, across all branches of practice or medical specialties (e.g. diagnostic, therapeutic, or surgical medicine), career stages, and practice settings (e.g. emergency care), appear to be critical for patient care. However, medical images and videos are not self-explanatory and, therefore, need to be interpreted by humans, i.e. medical experts. In addition, various types of degradations and artifacts may appear during image acquisition or processing, and consequently affect medical imaging data. Such distortions tend to impact viewers' quality of experience, as well as their clinical practice. It is accordingly essential to better understand how medical experts perceive the quality of visual content. Thankfully, progress has been made in the recent literature towards such understanding. In this article, we present an up-to-date state-of the-art of relatively recent (i.e. not older than ten years old) existing studies on the subjective quality assessment of medical images and videos, as well as research works using task-based approaches. Furthermore, we discuss the merits and drawbacks of the methodologies used, and we provide recommendations about experimental designs and statistical processes to evaluate the perception of medical images and videos for future studies, which could then be used to optimise the visual experience of image readers in real clinical practice. Finally, we tackle the issue of the lack of available annotated medical image and video quality databases, which appear to be indispensable for the development of new dedicated objective metrics

Multi-output speckle reduction filter for ultrasound medical images based on multiplicative multiresolution decomposition

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Filtre multi-sorties pour la réduction de bruit appliqué aux images médicales ultrasons

National audience– L'échographie est la modalité d'imagerie la plus répandue car la moins nocive. Cependant, la présence de bruit de « speckle » dans l'imagerie médicale ultrasonographique reste un inconvénient majeur. La principale limite des méthodes de réduction de bruits proposées est qu'une réduction efficace du bruit s'effectue au détriment de la qualité (lissage excessif, effet de flou, un aspect artificiel, ...). Dans cet article, nous proposons un nouveau filtre Multi-Sorties basé sur la Décomposition Multiplicative Multirésolutions (MOF-MMD). Cette méthode multi-échelles, particulièrement efficace dans le cas de bruit multiplicatif, améliore distinctement trois sorties: bords, texture, et image globale. Le filtre multi-sorties vise à offrir aux praticiens des images améliorées en fonction des besoins de diagnostic. Les différentes structures, textures et bordures sont filtrées selon l'image contour obtenue par des opérateurs de morphologie mathématique. Les images résultantes du filtrage sont évaluées et validées par comparaison avec deux méthodes de l'état de l'art. Abstract – Ultrasonographic examination, either as visual inspection or quantitative analysis, is less effective than other medical imaging systems due to speckle noise. In this paper, a new Multi-Output Filter based on a Multiplicative Multiresolution Decomposition (MOF-MMD) is proposed. This multiscale based method, particularly efficient in the case of multiplicative noise, enhances distinctively three outputs: edges, texture and the global image. Ultrasound is the most widespread imaging modality. However, it suffers from a major disadvantage as it is corrupted by speckle noise. The state-of-the-art speckle reduction methods often offers an effective speckle reduction at the expense of the quality (oversmoothig, blurring effect, artificial appearance...). In this paper, a new Multi-Output Filter based on a Multiplicative Multiresolution Decomposition (MOF-MMD) is proposed. This multiscale based method, particularly efficient in the case of multiplicative noise, enhances distinctively three outputs: edges, texture and the global image. The multi-output filter aims at offering an enhanced images according to the features desired by radiologists. The different structures, textures and edges are filtered according to the contour image obtained by morphological operators.The resulting images are evaluated and validated by comparison with two state-of-the-art methods

A thin two-phase foils deformed by an interfacial dislocation in anisotropic elasticity

The purpose of this work is the numerical resolution, in the case of anisotropic elasticity, of the problem of a dislocation parallel and near to the two free surfaces of a thin bicrystal. This case is obtained while making the period of a network of misfit dislocations much greater than the thickness of the two foils. As a result, in the vicinity of the dislocation, the limiting bondary conditions will be close to that of Volterra translation dislocation. The elastic fields of displacement and stress are calculated for various orientations of the burgers vector. Before this calculation, we tested the precision of the results of the program by comparing the interfacial relative displacement obtained from this one to the results of the analytical expression describing this same displacement. The thin bicristal Al/Al2Cu, that made the object of several investigations, is treated like example. The results obtained are compared to those obtained in isotropic elasticity.<br><br>Este trabajo aborda la resolución numérica en anisotropía elástica, del problema de una dislocación paralela cercana a las superficies libres de un bi-cristal delgado. Este problema se genera cuando el periodo de la red de dislocaciones desplazadas es mucho mayor que el espesor de la bi-lámina. Como resultados, en la vecindad de la dislocación, las condiciones de contorno estarán cercanas a la dislocación de traslación de Volterra. Los campos elásticos de desplazamiento y las tensiones se calcularon para distintas orientaciones del vector de burgers. Como paso previo a los cálculos, se comprobó la precisión de los resultados del programa comparando le desplazamiento relativo interracial obtenido con los resultados de la expresión analítica que describen dicho desplazamiento. Se emplearon como ejemplo bi-cristales de Al/Al2Cu, debido a su empleo en varias investigaciones. Los resultados fueron comparados con los obtenidos en elasticidad isótropa

Evaluation of No-reference quality metrics for Ultrasound liver images

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