De nos jours, il est devenu de plus en plus simple pour qui que ce soit de prendre des photos avec des appareils photo numériques, de télécharger ces images sur l'ordinateur et d'utiliser différents logiciels de traitement d'image pour appliquer des modification sur ces images (compression, débruitage, transmission, etc.). Cependant, ces traitements entraînent des dégradations qui influent sur la qualité visuelle de l'image. De plus, avec la généralisation de l'internet et la croissance de la messagerie électronique, des logiciels sophistiqués de retouche d'images se sont démocratisés permettant de falsifier des images à des fins légitimes ou malveillantes pour des communications confidentielles ou secrètes. Dans ce contexte, la stéganographie constitue une méthode de choix pour dissimuler et transmettre de l'information.Dans ce manuscrit, nous avons abordé deux problèmes : l'évaluation de la qualité d'image et la détection d'une modification ou la présence d'informations cachées dans une image. L'objectif dans un premier temps est de développer une mesure sans référence permettant d'évaluer de manière automatique la qualité d'une image en corrélation avec l'appréciation visuelle humaine. Ensuite proposer un outil de stéganalyse permettant de détecter, avec la meilleure fiabilité possible, la présence d'informations cachées dans des images naturelles. Dans le cadre de cette thèse, l'enjeu est de prendre en compte l'imperfection des données manipulées provenant de différentes sources d'information avec différents degrés de précision. Dans ce contexte, afin de profiter entièrement de l'ensemble de ces informations, nous proposons d'utiliser la théorie des fonctions de croyance. Cette théorie permet de représenter les connaissances d'une manière relativement naturelle sous la forme d'une structure de croyances. Nous avons proposé une nouvelle mesure sans référence d'évaluation de la qualité d'image capable d'estimer la qualité des images dégradées avec de multiple types de distorsion. Cette approche appelée wms-EVreg2 est basée sur la fusion de différentes caractéristiques statistiques, extraites de l'image, en fonction de la fiabilité de chaque ensemble de caractéristiques estimée à travers la matrice de confusion. À partir des différentes expérimentations, nous avons constaté que wms-EVreg2 présente une bonne corrélation avec les scores de qualité subjectifs et fournit des performances de prédiction de qualité compétitives par rapport aux mesures avec référence.Pour le deuxième problème abordé, nous avons proposé un schéma de stéganalyse basé sur la théorie des fonctions de croyance construit sur des sous-espaces aléatoires des caractéristiques. La performance de la méthode proposée a été évaluée sur différents algorithmes de dissimulation dans le domaine de transformé JPEG ainsi que dans le domaine spatial. Ces tests expérimentaux ont montré l'efficacité de la méthode proposée dans certains cadres d'applications. Cependant, il reste de nombreuses configurations qui résident indétectables. / Nowadays it has become increasingly simpler for anyone to take pictures with digital cameras, to download these images to the computer and to use different image processing software to apply modifications on these images (Compression, denoising, transmission, etc.). However, these treatments lead to degradations which affect the visual quality of the image. In addition, with the widespread use of the Internet and the growth of electronic mail, sophisticated image-editing software has been democratised allowing to falsify images for legitimate or malicious purposes for confidential or secret communications. In this context, steganography is a method of choice for embedding and transmitting information.In this manuscript we discussed two issues : the image quality assessment and the detection of modification or the presence of hidden information in an image. The first objective is to develop a No-Reference measure allowing to automatically evaluate the quality of an image in correlation with the human visual appreciation. Then we propose a steganalysis scheme to detect, with the best possible reliability, the presence of information embedded in natural images. In this thesis, the challenge is to take into account the imperfection of the manipulated data coming from different sources of information with different degrees of precision. In this context, in order to take full advantage of all this information, we propose to use the theory of belief functions. This theory makes it possible to represent knowledge in a relatively natural way in the form of a belief structure.We proposed a No-reference image quality assessment measure, which is able to estimate the quality of the degraded images with multiple types of distortion. This approach, called wms-EVreg2, is based on the fusion of different statistical features, extracted from the image, depending on the reliability of each set of features estimated through the confusion matrix. From the various experiments, we found that wms-EVreg2 has a good correlation with subjective quality scores and provides competitive quality prediction performance compared to Full-reference image quality measures.For the second problem addressed, we proposed a steganalysis scheme based on the theory of belief functions constructed on random subspaces of the features. The performance of the proposed method was evaluated on different steganography algorithms in the JPEG transform domain as well as in the spatial domain. These experimental tests have shown the performance of the proposed method in some application frameworks. However, there are many configurations that reside undetectable.

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This thesis studies the assessment of picture quality using the artificial neural network approach. In the first part, two main ways to evaluate the picture quality are described. It is the subjective assessment of picture quality, where a group of people watches the picture and evaluates its quality, and objective assessment which is based on mathematical relations. Calculation of structural similarity index (SSIM) is analyzed in detail. In the second part, the basis of neural networks is described. A neural network was created in Matlab, designed to simulate subjective assessment scores based on the SSIM index.

Research conducted in the aviation industry includes two major areas, increased safety and a reduction of the environmental footprint. This thesis investigates the possibilities of increased situational awareness with computer vision in avionics systems. Image fusion methods are evaluated with appropriate pre-processing of three image sensors, one in the visual spectrum and two in the infra-red spectrum. The sensor setup is chosen to cope with the different weather and operational conditions of an aircraft, with a focus on the final approach and landing phases. Extensive image quality assessment metrics derived from a systematic review is applied to provide a precise evaluation of the image quality of the fusion methods. A total of four image fusion methods are evaluated, where two are convolutional network-based, using the networks for feature extraction in the detailed layers. Other approaches with visual saliency maps and sparse representation are also evaluated. With methods implemented in MATLAB, results show that a conventional method implementing a rolling guidance filter for layer separation and visual saliency map provides the best results. The results are further confirmed with a subjective ranking test, where the image quality of the fusion methods is evaluated further.

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abstract: The depth richness of a scene translates into a spatially variable defocus blur in the acquired image. Blurring can mislead computational image understanding; therefore, blur detection can be used for selective image enhancement of blurred regions and the application of image understanding algorithms to sharp regions. This work focuses on blur detection and its application to image enhancement. This work proposes a spatially-varying defocus blur detection based on the quotient of spectral bands; additionally, to avoid the use of computationally intensive algorithms for the segmentation of foreground and background regions, a global threshold defined using weak textured regions on the input image is proposed. Quantitative results expressed in the precision-recall space as well as qualitative results overperform current state-of-the-art algorithms while keeping the computational requirements at competitive levels. Imperfections in the curvature of lenses can lead to image radial distortion (IRD). Computer vision applications can be drastically affected by IRD. This work proposes a novel robust radial distortion correction algorithm based on alternate optimization using two cost functions tailored for the estimation of the center of distortion and radial distortion coefficients. Qualitative and quantitative results show the competitiveness of the proposed algorithm. Blur is one of the causes of visual discomfort in stereopsis. Sharpening applying traditional algorithms can produce an interdifference which causes eyestrain and visual fatigue for the viewer. A sharpness enhancement method for stereo images that incorporates binocular vision cues and depth information is presented. Perceptual evaluation and quantitative results based on the metric of interdifference deviation are reported; results of the proposed algorithm are competitive with state-of-the-art stereo algorithms. Digital images and videos are produced every day in astonishing amounts. Consequently, the market-driven demand for higher quality content is constantly increasing which leads to the need of image quality assessment (IQA) methods. A training-free, no-reference image sharpness assessment method based on the singular value decomposition of perceptually-weighted normalized-gradients of relevant pixels in the input image is proposed. Results over six subject-rated publicly available databases show competitive performance when compared with state-of-the-art algorithms. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2019

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Aim This study aimed to evaluate the effectiveness of the Van Beek activator in treating Class II malocclusions in the university student clinic, and to identify factors influencing treatment success. Additionally, a qualitative assessment was conducted to evaluate the quality of the recorded orthodontic journals by the students of the clinic and to rate the degree of adherence to the policy-clinic template. Material and method Data from 229 patients who had their treatment finished within the years 2012-2022 at the university clinic, including in-house and referred patients, were collected and analysed using SPSS. Results The orthodontic journals maintained a high quality, while following annotations for check-ups and end of treatment varied in quality. The success rate of Van Beek treatments was approximately 69%, which is comparable to previous studies done at the university clinic. The degree of patient cooperation was found to be significantly associated with treatment outcome, with patients who showed excellent cooperation achieving the pre-set treatment aims more frequently. Referred patients showed a higher degree of cooperation and better treatment outcomes compared to in-house patients, possibly due to a higher treatment need and more serious response to the treatment. Conclusion The Van Beek activator was found to be effective in reducing overjet, as previously reported in functional appliance studies. Overall, the study highlights the importance of patient motivation and cooperation in achieving successful orthodontic treatment outcomes. Further studies are needed to evaluate the long-term effectiveness of the Van Beek activator and to confirm the findings of this study. / Syfte Syftet med studien var att utvärdera effektiviteten av van Beek-aktivatorn vid behandling av postnormalt bett på Malmö universitets studentklinik, och att identifiera faktorer som påverkar lyckandet av behandling. Utöver det utfördes även en kvalitetsgranskning av de utförda behandlingarna för att utvärdera kvalitén på studenternas ortodontijournalanteckningar och följsamheten till journalmallen vid start av behandling. Material och metod Data från totalt 229 patienter, både remitterade och interna, som avslutade sina behandlingar på studentkliniken mellan år 2012–2022, samlades in och analyserades med hjälp av SPSS. Resultat Ortodontijournalanteckningarna höll en hög kvalitet, medan anteckningar för kontroller och avslutande av behandlingar varierade i kvalitet. Lyckandefrekvensen för van Beek-behandlingar var ca 69%, vilket är jämförbart med tidigare utförda studier på studentkliniker. Graden av kooperation visade sig vara signifikant associerad med behandlingsresultat, där patienter med utmärkt kooperation uppnådde behandlingsmålen i högre grad än övriga patienter. Remitterade patienter koopererade bättre än interna patienter och uppnådde i större utsträckning lyckade behandlingsresultat, möjligtvis på grund av ett större behandlingsbehov och en mer seriös respons på behandling. Slutsats Van Beek-aktivatorn var effektiv vid minskning av HÖB, som tidigare rapporterats i studier på avtagbara tandställningar. Studien belyser vikten av patienters motivation och kooperation för att uppnå lyckade behandlingsresultat. Ytterligare studier behöver utföras för att utvärdera den långsiktiga effektiviteten av Van Beek-aktivatorn, samt att bekräfta fynden i studien.

This research has been conducted at Hunter Engineering Company. It aims to Design a Kit Packing Weighing System which performs a Quality Assessment of tool-kits while packing them on weighing scales. The main aspects of Kit-Packing are documented and suitable terminologies to address the process are established. The kits are categorized and a process for packing kits of different categories is suggested. A system to weigh Heavy, Medium and Light kits is presented. A Monte-Carlo Simulation Tool is developed and an Analysis using the Risk Solver Software is conducted to select the preferable method of establishing Tolerance Limits. A design for a Visual Basic coded Interface is outlined that will guide the Operator through the kit packing process and indicate whether to Accept or Inspect the kit. A Windows application of the Software was prototyped to demonstrate the System’s functionality which also is documented herein.

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