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In this paper, a content adaptive coding method for plenoptic video is proposed to reduce both of the spatial and temporal redundancy. Based on the spatial correlations among subapertures, the plenoptic video is divided into two subaperture groups: the central view videos and the residual videos. Coding methods, multiview coding method based on spatial correlation(S-MVC) and multiview coding method based on temporal correlation(T-MVC), are adopted for residual videos according to correlation and residual energy analysis, while the central view videos are always encoded by S-MVC. Correlation analysis is performed first, and residual energy analysis is further performed if necessary. Coding the central view videos and the residual videos separately reduces bitstream, choosing different encoding methods for residual videos makes full use of the characteristics of different video content. Both the central view videos and the residual videos are compressed by MV-HEVC. The experimental results demonstrate that the proposed method outperforms a pseudo-sequence-based MVC method for plenoptic video by an average of 25.06% bitrate saving.

Efficient video compression algorithms in advanced multimedia broadcasting systems are in high demand. In the last decades, different video compression tools have been developed which can influence the final Quality of Experience in different ways. This paper has two goals. The first goal is to present a study of different compression algorithms available for stereoscopic 3D videos. The second goal is to present the possibilities in the creation of new stereoscopic models. The well-established video codecs (AVC, MVC, HEVC and MV-HEVC) are considered as encoders. Generic objective video quality metrics are used to analyze the compression efficiencies of the considered codecs, extended with results from subjective tests. The correlations between the objective and subjective scores are analyzed statistically. Due to unsatisfactory results of generic 2D metrics for the stereoscopic sequences used in the test, new objective models are presented. Such models show improved correlation with subjective stereoscopic video quality. The validation, verification and a description of models are presented in detail.

The acquisition of the spatial and angular information of a scene using light field (LF) technologies supplement a wide range of post-processing applications, such as scene reconstruction, refocusing, virtual view synthesis, and so forth. The additional angular information possessed by LF data increases the size of the overall data captured while offering the same spatial resolution. The main contributor to the size of captured data (i.e., angular information) contains a high correlation that is exploited by state-of-the-art video encoders by treating the LF as a pseudo video sequence (PVS). The interpretation of LF as a single PVS restricts the encoding scheme to only utilize a single-dimensional angular correlation present in the LF data. In this paper, we present an LF compression framework that efficiently exploits the spatial and angular correlation using a multiview extension of high-efficiency video coding (MV-HEVC). The input LF views are converted into multiple PVSs and are organized hierarchically. The rate-allocation scheme takes into account the assigned organization of frames and distributes quality/bits among them accordingly. Subsequently, the reference picture selection scheme prioritizes the reference frames based on the assigned quality. The proposed compression scheme is evaluated by following the common test conditions set by JPEG Pleno. The proposed scheme performs 0.75 dB better compared to state-of-the-art compression schemes and 2.5 dB better compared to the ×265-based JPEG Pleno anchor scheme. Moreover, an optimized motion-search scheme is proposed in the framework that reduces the computational complexity (in terms of the sum of absolute difference [SAD] computations) of motion estimation by up to 87% with a negligible loss in visual quality (approximately 0.05 dB).

Computational imaging and light field technology promise to deliver the required six-degrees-of-freedom for natural scenes in virtual reality. Already existing extensions of standardized video coding formats, such as multi-view coding and multi-view plus depth, are the most conventional light field video coding solutions at the moment. The latest multi-view coding format, which is a direct extension of the high efficiency video coding (HEVC) standard, is called multi-view HEVC (or MV-HEVC). MV-HEVC treats each light field view as a separate video sequence, and uses syntax elements similar to standard HEVC for exploiting redundancies between neighboring views. To achieve this, inter-view and temporal prediction schemes are deployed with the aim to find the most optimal trade-off between coding performance and reconstruction quality. The number of possible prediction structures is unlimited and many of them are proposed in the literature. Although some of them are efficient in terms of compression ratio, they complicate random access due to the dependencies on previously decoded pixels or frames. Random access is an important feature in video delivery, and a crucial requirement in multi-view video coding. In this work, we propose and compare different prediction structures for coding light field video using MV-HEVC with a focus on both compression efficiency and random accessibility. Experiments on three different short-baseline light field video sequences show the trade-off between bit-rate and distortion, as well as the average number of decoded views/frames, necessary for displaying any random frame at any time instance. The findings of this work indicate the most appropriate prediction structure depending on the available bandwidth and the required degree of random access.

Light field video is a promising technology for delivering the required six-degrees-of-freedom for natural content in virtual reality. Already existing multi-view coding (MVC) and multi-view plus depth (MVD) formats, such as MV-HEVC and 3D-HEVC, are the most conventional light field video coding solutions since they can compress video sequences captured simultaneously from multiple camera angles. 3D-HEVC treats a single view as a video sequence and the other sub-aperture views as gray-scale disparity (depth) maps. On the other hand, MV-HEVC treats each view as a separate video sequence, which allows the use of motion compensated algorithms similar to HEVC. While MV-HEVC and 3D-HEVC provide similar results, MV-HEVC does not require any disparity maps to be readily available, and it has a more straightforward implementation since it only uses syntax elements rather than additional prediction tools for inter-view prediction. However, there are many degrees of freedom in choosing an appropriate structure and it is currently still unknown which one is optimal for a given set of application requirements. In this work, various prediction structures for MV-HEVC are implemented and tested. The findings reveal the trade-off between compression gains, distortion and random access capabilities in MVHEVC light field video coding. The results give an overview of the most optimal solutions developed in the context of this work, and prediction structure algorithms proposed in state-of-the-art literature. This overview provides a useful benchmark for future development of light field video coding solutions.

The Multi-View extension of High Efficiency Video Coding (MV-HEVC) has improved the coding efficiency of multi-view videos, but this comes at the cost of the extra coding complexity of the MV-HEVC encoder. This coding complexity can be reduced by efficiently reducing time-consuming encoding operations. In this work, we propose two methods to reduce the encoder complexity. The first one is Early Coding unit Splitting (ECS), and the second is the Efficient Reference Picture Selection (ERPS) method. In the ECS method, the decision of Coding Unit (CU) splitting for dependent views is made on the CU splitting information obtained from the base view, while the ERPS method for dependent views is based on selecting reference pictures on the basis of the temporal location of the picture being encoded. Simulation results reveal that our proposed methods approximately reduce the encoding time by 58% when compared with HTM (16.2), the reference encoder for MV-HEVC.

الفيديو متعدد المناظر (ف.م.م، MVV) يمثل صيغة متقدمة لتكنولوجيا الفيديو الثلاثي الأبعاد. الفيديو متعدد المناظر يوفر تجربة ثلاثية أبعاد غنية مقارنة بالفيديو ثلاثي الابعاد ذو المنظرين فقط. يتعلق محتوى ف.م.م بعدة متغيرات من بينها عدد الكاميرات المستخدمة، زويا التصوير إضافة إلى المشهد المُصوّر. ينتج عن كل كاميرا مستخدمة محتوى معلومات إضافي بالمقارنة مع الفيديو الثنائي الأبعاد التقليدي. ال ف.م.م يحتاج الى تقنيات ضغط وترميز خاصة تأخذ بعين الاعتبار التشابه الموجود بين مجموعة المناظر أو الكاميرات المستخدمة. يمكن استغلال كلٌ من التشابه الزمني والجهوي لتحسن كفاءة الضغط. يمثل ضاغط الفيديو متعدد المناظر MVC الامتداد النموذجي لضاغط الفيديو H.264، حيث يوفر كفاءة ضغط أفضل تصل الى نسبة 50 بالمئة بالمقارنة مع H.264 المنفرد. رغم ذلك، كفاءة ضغط أفضل يمكن أن تقودنا الى تعقيد أكثر في خاصية الوصول العشوائي مما قد يعيق استخدام MVC في تطبيقات مثل FVT والارسال المباشر عبر 3DTV . كما قد يخفض ذلك من جودة التجربة للمشاهدين بما أن خاصية التفاعل أبطأ. تهدف هذه الرسالة الى دراسة ال MVC بطريقة معمقة وحل الإشكالية السابق ذكرها بخصوص قدرة الوصول العشوائي عبر اقتراح مقاربات هياكل تنبؤ أسرع. تهدف المقاربة الأولى المقترحة (PBI) إلى خفض تكلفة الوصول العشوائي إلى أي صورة في أي موقع ولحظة مقارنة مع النموذج المرجعي JMVM ونماذج حديثة أخرى. يستند المخطط PBI بالأساس إلى استخدام جهتين مرجعيتين (I-views) محددتي التموقع ضمن هيكلة ما بين المناظر، هذا مقابل استخدام جهة مرجعية واحدة في النموذج الأصلي. يتيح هذا تنبؤا مباشرا للجهات المتبقية ويضمن قدرة وصول عشوائي بأقل تكلفة مع الحفاظ على معدل ضغط منافس. مقارنة مع هيكلة MVC الأصلية، تحقق PBI ربحا في الوصول العشوائي بمقدار 20 بالمئة بالنسبة. تتفوق المقاربة الثانية المقترحة PIP على هيكلة PBI وتحرز ربحا بمقدار 53.33 بالمئة بالمقارنة مع هيكلة MVC الأصلي. تم اقتراح واعتماد طريقة جديدة GR لتقييم قدرة الوصول العشوائي عبر الأجزاء التجريبية للرسالة. تسمح هذه الطريقة بتقييم أكثر دقة حيث تأخذ بعين الاعتبار جميع أنواع الصور الموجودة ضمن الهياكل المتعددة المناظر المدروسة. كما تعرض الرسالة مقارنة استقصائية بين هياكل تنبؤ متعددة المناظر مقترحة ومنقولة. نتائج هذه التجارب تسمح بترتيب الهياكل المدروسة إضافة الى خيارات حجوم GOP بالتناسب مع تأثيراتها على قدرة الوصول العشوائي وكفاءة الضغط. أخيرا، أجريت المزيد من التجارب للمقارنة بين MVC و MV-HEVC فيما يتعلق بكفاءة الضغط، باستخدام فيديوهات متعددة مناظر لها أشكال ومقاييس متباينة.; Multiview video (MVV) is an advanced representation of 3D video technology. The MVV content depends on several parameters such as the deployed cameras number, recording angles and the captured scene. Each used camera inherently generates an extra amount of data compared to the 2D conventional video that only needs one camera. MVV needs specific coding techniques that take into consideration the visual similarities between the viewpoints set. Both temporal and interview correlations could be exploited to improve the compression ratios. Multiview video coding (MVC) is the extended profile of H.264/AVC video codec. MVC offers compression efficiency improvements achieving 50 % over simulcast video coding. However, better compression performance leads to higher random access complexity which might hamper MVC usage in applications such as Free viewpoint Television and 3D TV broadcasting. It also degrades the viewers quality of experience due to the lack of interactivity. This thesis aims to study MVC encoding and to solve the aforementioned problem of Random Access (RA) ability by proposing faster interview prediction approaches. The thesis first presents a brief description of the 3D video concepts from capturing to displaying. Furthermore, it focuses on video coding fundamentals and its multiview extension form. The thesis then proposes two novel techniques to enhance the random access ability of the MVC encoder. The first proposed approach (PBI) aims to lower the cost of randomly accessing any picture at any position and instant, with respect to the multiview reference model JMVM and other state-of-the-art methods.The proposed (PBI) scheme is mainly based on the use of two base views (I-views) in the interview structure with selected positions instead of only a single reference view as in the standard structure. This provides a direct interview prediction for the remaining views and ensures faster random access ability while maintaining a competitive compression performance. PBI achieves a random access gain of 20 % relative to the reference model MVC. The second proposed approach (PIP) surpasses PBI structure by achieving a random access gain of 53.33% compared to the benchmark standard MVC. A novel random access ability evaluation method (GR) has been suggested and adopted throughout the thesis experimental parts. It allows more accurate assessment by considering all pictures types of the tested multiview schemes. A comparative investigation of proposed and reported multiview schemes is also presented in this thesis. Results of the conducted tests allow classifying the examined multiview schemes and GOP sizes preferences according to their effects in terms of random access ability and compression efficiency. Finally, more experiments have been conducted comparing MVC and MV-HEVC standards in terms of compression efficiency using different multiview video sequences that have different textures and resolutions.; La vidéo multi-vues (MVV) est une représentation avancée de la technologie vidéo 3D. Le contenu MVV dépend de plusieurs paramètres tels que le nombre de caméras déployées, les angles d'enregistrement et la scène capturée. Chaque caméra utilisée génère intrinsèquement une quantité de données supplémentaire par rapport à la vidéo classique en 2D qui ne nécessite qu'une seule caméra. Le MVV nécessite des techniques de codage spécifiques qui prennent en compte les similitudes visuelles entre les points de vue définis. Les corrélations temporelles et d'interview pourraient être exploitées pour améliorer les taux de compression. Le codage vidéo multi-vues (MVC) est le profil étendu du codec vidéo H.264/AVC. Le MVC offre des améliorations de l'efficacité de la compression atteignant 50 % par rapport au codage vidéo en diffusion simultanée. Toutefois, de meilleures performances de compression entraînent une plus grande complexité d'accès aléatoire qui pourrait entraver l'utilisation du MVC dans des applications telles que la télévision à point de vue libre et la diffusion de télévision en 3D. Elle dégrade également la qualité de l'expérience des téléspectateurs en raison du manque d'interactivité. Cette thèse vise à étudier l'encodage MVC et à résoudre le problème susmentionné de la capacité d'accès aléatoire (RA) en proposant des approches plus rapides de prédiction des interviews. La thèse présente d'abord une brève description des concepts de la vidéo 3D, de la capture à l'affichage. De plus, elle se concentre sur les principes fondamentaux du codage vidéo et sa forme d'extension multi-vues. La thèse propose ensuite deux nouvelles techniques pour améliorer la capacité d'accès aléatoire de l'encodeur MVC. La première approche proposée (PBI) vise à réduire le coût de l'accès aléatoire à n'importe quelle image, à n'importe quelle position et à n'importe quel instant, par rapport au modèle de référence multi-vues JMVM et à d'autres méthodes de pointe. Le schéma proposé (PBI) est principalement basé sur l'utilisation de deux vues de base (I-vues) dans la structure d'interview avec des positions sélectionnées au lieu d'une seule vue de référence comme dans la structure standard. Cela permet de prévoir directement les entretiens pour les autres vues et d'assurer un accès aléatoire plus rapide tout en maintenant une performance de compression compétitive. La PBI permet d'obtenir un gain d'accès aléatoire de 20 % par rapport au modèle de référence MVC. La deuxième approche proposée (PIP) surpasse la structure PBI en réalisant un gain d'accès aléatoire de 53,33 % par rapport au modèle MVC standard de référence. Une nouvelle méthode d'évaluation de la capacité d'accès aléatoire (GR) a été suggérée et adoptée tout au long des parties expérimentales de la thèse. Elle permet une évaluation plus précise en considérant tous les types d'images des schémas multi-vues testés. Une étude comparative des schémas multi-vues proposés et rapportés est également présentée dans cette thèse. Les résultats des tests effectués permettent de classer les schémas multi-vues examinés et les préférences de taille des GOP en fonction de leurs effets en termes de capacité d'accès aléatoire et d'efficacité de la compression. Enfin, d'autres expériences ont été menées pour comparer les normes MVC et MV-HEVC en termes d'efficacité de compression en utilisant différentes séquences vidéo multi-vues qui ont des textures et des résolutions différentes.

With the advent of light field acquisition technologies, the captured information of the scene is enriched by having both angular and spatial information. The captured information provides additional capabilities in the post processing stage, e.g. refocusing, 3D scene reconstruction, synthetic aperture etc. Light field capturing devices are classified in two categories. In the first category, a single plenoptic camera is used to capture a densely sampled light field, and in second category, multiple traditional cameras are used to capture a sparsely sampled light field. In both cases, the size of captured data increases with the additional angular information. The recent call for proposal related to compression of light field data by JPEG, also called “JPEG Pleno”, reflects the need of a new and efficient light field compression solution. In this paper, we propose a compression solution for sparsely sampled light field data. In a multi-camera system, each view depicts the scene from a single perspective. We propose to interpret each single view as a frame of pseudo video sequence. In this way, complete MxN views of multi-camera system are treated as M pseudo video sequences, where each pseudo video sequence contains N frames. The central pseudo video sequence is taken as base View and first frame in all the pseudo video sequences is taken as base Picture Order Count (POC). The frame contained in base view and base POC is labeled as base frame. The remaining frames are divided into three predictor levels. Frames placed in each successive level can take prediction from previously encoded frames. However, the frames assigned with last prediction level are not used for prediction of other frames. Moreover, the rate-allocation for each frame is performed by taking into account its predictor level, its frame distance and view wise decoding distance relative to the base frame. The multi-view extension of high efficiency video coding (MV-HEVC) is used to compress the pseudo multi-view sequences. The MV-HEVC compression standard enables the frames to take prediction in both direction (horizontal and vertical d), and MV-HEVC parameters are used to implement the proposed 2D prediction and rate allocation scheme. A subset of four light field images from Stanford dataset are compressed, using the proposed compression scheme on four bitrates in order to cover the low to high bit-rates scenarios. The comparison is made with state-of-art reference encoder HEVC and its real-time implementation X265. The 17x17 grid is converted into a single pseudo sequence of 289 frames by following the order explained in JPEG Pleno call for proposal and given as input to the both reference schemes. The rate distortion analysis shows that the proposed compression scheme outperforms both reference schemes in all tested bitrate scenarios for all test images. The average BD-PSNR gain is 1.36 dB over HEVC and 2.15 dB over X265.

الفيديو متعدد المناظر (ف.م.م، MVV) يمثل صيغة متقدمة لتكنولوجيا الفيديو الثلاثي الأبعاد. الفيديو متعدد المناظر يوفر تجربة ثلاثية أبعاد غنية مقارنة بالفيديو ثلاثي الابعاد ذو المنظرين فقط. يتعلق محتوى ف.م.م بعدة متغيرات من بينها عدد الكاميرات المستخدمة، زويا التصوير إضافة إلى المشهد المُصوّر. ينتج عن كل كاميرا مستخدمة محتوى معلومات إضافي بالمقارنة مع الفيديو الثنائي الأبعاد التقليدي. ال ف.م.م يحتاج الى تقنيات ضغط وترميز خاصة تأخذ بعين الاعتبار التشابه الموجود بين مجموعة المناظر أو الكاميرات المستخدمة. يمكن استغلال كلٌ من التشابه الزمني والجهوي لتحسن كفاءة الضغط. يمثل ضاغط الفيديو متعدد المناظر MVC الامتداد النموذجي لضاغط الفيديو H.264، حيث يوفر كفاءة ضغط أفضل تصل الى نسبة 50 بالمئة بالمقارنة مع H.264 المنفرد. رغم ذلك، كفاءة ضغط أفضل يمكن أن تقودنا الى تعقيد أكثر في خاصية الوصول العشوائي مما قد يعيق استخدام MVC في تطبيقات مثل FVT والارسال المباشر عبر 3DTV . كما قد يخفض ذلك من جودة التجربة للمشاهدين بما أن خاصية التفاعل أبطأ. تهدف هذه الرسالة الى دراسة ال MVC بطريقة معمقة وحل الإشكالية السابق ذكرها بخصوص قدرة الوصول العشوائي عبر اقتراح مقاربات هياكل تنبؤ أسرع. تهدف المقاربة الأولى المقترحة (PBI) إلى خفض تكلفة الوصول العشوائي إلى أي صورة في أي موقع ولحظة مقارنة مع النموذج المرجعي JMVM ونماذج حديثة أخرى. يستند المخطط PBI بالأساس إلى استخدام جهتين مرجعيتين (I-views) محددتي التموقع ضمن هيكلة ما بين المناظر، هذا مقابل استخدام جهة مرجعية واحدة في النموذج الأصلي. يتيح هذا تنبؤا مباشرا للجهات المتبقية ويضمن قدرة وصول عشوائي بأقل تكلفة مع الحفاظ على معدل ضغط منافس. مقارنة مع هيكلة MVC الأصلية، تحقق PBI ربحا في الوصول العشوائي بمقدار 20 بالمئة بالنسبة. تتفوق المقاربة الثانية المقترحة PIP على هيكلة PBI وتحرز ربحا بمقدار 53.33 بالمئة بالمقارنة مع هيكلة MVC الأصلي. تم اقتراح واعتماد طريقة جديدة GR لتقييم قدرة الوصول العشوائي عبر الأجزاء التجريبية للرسالة. تسمح هذه الطريقة بتقييم أكثر دقة حيث تأخذ بعين الاعتبار جميع أنواع الصور الموجودة ضمن الهياكل المتعددة المناظر المدروسة. كما تعرض الرسالة مقارنة استقصائية بين هياكل تنبؤ متعددة المناظر مقترحة ومنقولة. نتائج هذه التجارب تسمح بترتيب الهياكل المدروسة إضافة الى خيارات حجوم GOP بالتناسب مع تأثيراتها على قدرة الوصول العشوائي وكفاءة الضغط. أخيرا، أجريت المزيد من التجارب للمقارنة بين MVC و MV-HEVC فيما يتعلق بكفاءة الضغط، باستخدام فيديوهات متعددة مناظر لها أشكال ومقاييس متباينة., Multiview video (MVV) is an advanced representation of 3D video technology. The MVV content depends on several parameters such as the deployed cameras number, recording angles and the captured scene. Each used camera inherently generates an extra amount of data compared to the 2D conventional video that only needs one camera. MVV needs specific coding techniques that take into consideration the visual similarities between the viewpoints set. Both temporal and interview correlations could be exploited to improve the compression ratios. Multiview video coding (MVC) is the extended profile of H.264/AVC video codec. MVC offers compression efficiency improvements achieving 50 % over simulcast video coding. However, better compression performance leads to higher random access complexity which might hamper MVC usage in applications such as Free viewpoint Television and 3D TV broadcasting. It also degrades the viewers quality of experience due to the lack of interactivity. This thesis aims to study MVC encoding and to solve the aforementioned problem of Random Access (RA) ability by proposing faster interview prediction approaches. The thesis first presents a brief description of the 3D video concepts from capturing to displaying. Furthermore, it focuses on video coding fundamentals and its multiview extension form. The thesis then proposes two novel techniques to enhance the random access ability of the MVC encoder. The first proposed approach (PBI) aims to lower the cost of randomly accessing any picture at any position and instant, with respect to the multiview reference model JMVM and other state-of-the-art methods.The proposed (PBI) scheme is mainly based on the use of two base views (I-views) in the interview structure with selected positions instead of only a single reference view as in the standard structure. This provides a direct interview prediction for the remaining views and ensures faster random access ability while maintaining a competitive compression performance. PBI achieves a random access gain of 20 % relative to the reference model MVC. The second proposed approach (PIP) surpasses PBI structure by achieving a random access gain of 53.33% compared to the benchmark standard MVC. A novel random access ability evaluation method (GR) has been suggested and adopted throughout the thesis experimental parts. It allows more accurate assessment by considering all pictures types of the tested multiview schemes. A comparative investigation of proposed and reported multiview schemes is also presented in this thesis. Results of the conducted tests allow classifying the examined multiview schemes and GOP sizes preferences according to their effects in terms of random access ability and compression efficiency. Finally, more experiments have been conducted comparing MVC and MV-HEVC standards in terms of compression efficiency using different multiview video sequences that have different textures and resolutions., La vidéo multi-vues (MVV) est une représentation avancée de la technologie vidéo 3D. Le contenu MVV dépend de plusieurs paramètres tels que le nombre de caméras déployées, les angles d'enregistrement et la scène capturée. Chaque caméra utilisée génère intrinsèquement une quantité de données supplémentaire par rapport à la vidéo classique en 2D qui ne nécessite qu'une seule caméra. Le MVV nécessite des techniques de codage spécifiques qui prennent en compte les similitudes visuelles entre les points de vue définis. Les corrélations temporelles et d'interview pourraient être exploitées pour améliorer les taux de compression. Le codage vidéo multi-vues (MVC) est le profil étendu du codec vidéo H.264/AVC. Le MVC offre des améliorations de l'efficacité de la compression atteignant 50 % par rapport au codage vidéo en diffusion simultanée. Toutefois, de meilleures performances de compression entraînent une plus grande complexité d'accès aléatoire qui pourrait entraver l'utilisation du MVC dans des applications telles que la télévision à point de vue libre et la diffusion de télévision en 3D. Elle dégrade également la qualité de l'expérience des téléspectateurs en raison du manque d'interactivité. Cette thèse vise à étudier l'encodage MVC et à résoudre le problème susmentionné de la capacité d'accès aléatoire (RA) en proposant des approches plus rapides de prédiction des interviews. La thèse présente d'abord une brève description des concepts de la vidéo 3D, de la capture à l'affichage. De plus, elle se concentre sur les principes fondamentaux du codage vidéo et sa forme d'extension multi-vues. La thèse propose ensuite deux nouvelles techniques pour améliorer la capacité d'accès aléatoire de l'encodeur MVC. La première approche proposée (PBI) vise à réduire le coût de l'accès aléatoire à n'importe quelle image, à n'importe quelle position et à n'importe quel instant, par rapport au modèle de référence multi-vues JMVM et à d'autres méthodes de pointe. Le schéma proposé (PBI) est principalement basé sur l'utilisation de deux vues de base (I-vues) dans la structure d'interview avec des positions sélectionnées au lieu d'une seule vue de référence comme dans la structure standard. Cela permet de prévoir directement les entretiens pour les autres vues et d'assurer un accès aléatoire plus rapide tout en maintenant une performance de compression compétitive. La PBI permet d'obtenir un gain d'accès aléatoire de 20 % par rapport au modèle de référence MVC. La deuxième approche proposée (PIP) surpasse la structure PBI en réalisant un gain d'accès aléatoire de 53,33 % par rapport au modèle MVC standard de référence. Une nouvelle méthode d'évaluation de la capacité d'accès aléatoire (GR) a été suggérée et adoptée tout au long des parties expérimentales de la thèse. Elle permet une évaluation plus précise en considérant tous les types d'images des schémas multi-vues testés. Une étude comparative des schémas multi-vues proposés et rapportés est également présentée dans cette thèse. Les résultats des tests effectués permettent de classer les schémas multi-vues examinés et les préférences de taille des GOP en fonction de leurs effets en termes de capacité d'accès aléatoire et d'efficacité de la compression. Enfin, d'autres expériences ont été menées pour comparer les normes MVC et MV-HEVC en termes d'efficacité de compression en utilisant différentes séquences vidéo multi-vues qui ont des textures et des résolutions différentes.

Light field imaging based on microlens arrays - also known as plenoptic, holoscopic and integral imaging - has recently risen up as feasible and prospective technology due to its ability to support functionalities not straightforwardly available in conventional imaging systems, such as: post-production refocusing and depth of field changing. However, to gradually reach the consumer market and to provide interoperability with current 2D and 3D representations, a display scalable coding solution is essential. In this context, this paper proposes an improved display scalable light field codec comprising a three-layer hierarchical coding architecture (previously proposed by the authors) that provides interoperability with 2D (Base Layer) and 3D stereo and multiview (First Layer) representations, while the Second Layer supports the complete light field content. For further improving the compression performance, novel exemplar-based inter-layer coding tools are proposed here for the Second Layer, namely: (i) an inter-layer reference picture construction relying on an exemplar-based optimization algorithm for texture synthesis, and (ii) a direct prediction mode based on exemplar texture samples from lower layers. Experimental results show that the proposed solution performs better than the tested benchmark solutions, including the authors' previous scalable codec. info:eu-repo/semantics/acceptedVersion

In recent years, 3D camera products and prototypes based on Integral imaging (II) technique have gradually emerged and gained broad attention. II is a method that spatially samples the natural light (light field) of a scene, usually using a microlens array or a camera array and records the light field using a high resolution 2D image sensor. The large amount of data generated by II and the redundancy it contains together lead to the need for an efficient compression scheme. During recent years, the compression of 3D integral images has been widely researched. Nevertheless, there have not been many approaches proposed regarding the compression of integral videos (IVs). The objective of the thesis is to investigate efficient coding methods for integral videos. The integral video frames used are captured by the first consumer used light field camera Lytro. One of the coding methods is to encode the video data directly by an H.265/HEVC encoder. In other coding schemes the integral video is first converted to an array of sub-videos with different view perspectives. The sub-videos are then encoded either independently or following a specific reference picture pattern which uses a MVHEVC encoder. In this way the redundancy between the multi-view videos is utilized instead of the original elemental images. Moreover, by varying the pattern of the subvideo input array and the number of inter-layer reference pictures, the coding performance can be further improved. Considering the intrinsic properties of the input video sequences, a QP-per-layer scheme is also proposed in this thesis. Though more studies would be required regarding time and complexity constraints for real-time applications as well as dramatic increase of number of views, the methods proposed inthis thesis prove to be an efficient compression for integral videos.