Analysis of Content Quality Evaluation within 3DTV Service Distribution Systems, Journal of Telecommunications and Information Technology, 2014, nr 1

In the following paper, evaluation of quality of content distributed within 3DTV service is assessed. The performed analysis reveals a multiplicity of parameters as a compound factor defining the contemporary approach towards quality assessment. Taking into consideration a successful telecommunication service creation, an examination of content chain identifies crucial stages founding the path of modern services of stereoscopic content distribution quality evaluation

Subjective evaluation of an active crosstalk reduction system for mobile autostereoscopic displays

The Quality of Experience (QoE) provided by autostereoscopic 3D displays strongly depends on the user position. For an optimal image quality, the observer should be located at one of the relevant positions, called sweet spots, where artifacts reducing the QoE, such as crosstalk, are minimum. In this paper, we propose and evaluate a complete active crosstalk reduction system running on an HTC EVO 3D smartphone. To determine the crosstalk level at each position, a full display characterization was performed. Based on the user position and crosstalk profile, the system first helps the user to find the sweet spot using visual feedback. If the user moves away from the sweet spot, then the active crosstalk compensation is performed and reverse stereo phenomenon is corrected. The user preference between standard 2D and 3D modes, and the proposed system was evaluated through a subjective quality assessment. Results show that in terms of depth perception, the proposed system clearly outperforms the 3D and 2D modes. In terms of image quality, 2D mode was found to be best, but the proposed system outperforms 3D mode

포토폴리머 상의 홀로그래픽 기록 기술을 이용한 무안경식 삼차원 이미징 방법

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2014. 8. 이병호.이 박사학위 논문에서는 새로운 홀로그래픽 기록방법들을 이용하여 기존의 무안경식 삼차원 디스플레이의 제한점들을 개선하는 방법에 대해 논한다. 두 종류의 새로운 홀로그래픽 기록방법을 무안경식 삼차원 디스플레이를 구현하기 위해 제안한다. 첫 번째 방법은 호겔 중첩을 이용하여 홀로그래픽 스테레오그램의 해상도를 증가시키는 방법이며, 다른 하나의 방법은 렌즈어레이 홀로그래픽 광학소자를 이용하여 투명한 특성을 가지는 이차원 및 삼차원 영상을 구현하는 방법이다. 이 박사학위 논문에서는 홀로그래픽 기록매질로 광중합체 필름을 사용한다. 단일파장 기록방법과 세 파장 다중화 기록방법을 이용해 제작된 광중합체 필름 상에 기록되는 체적홀로그램에 대한 노출반응 특성을 실험을 통해 분석한다. 광중합체 필름에 기록된 세 파장 다중화된 홀로그램의 투명한 특성과 회절효율을 재생실험을 통해 평가하며, 광중합체 필름의 수축특성에 대해 이론적으로 분석하고 실험적으로 검증한다. 홀로그래픽 프린팅 방법을 이용해 기록된 홀로그래픽 스테레오그램의 해상도를 증가시키기 위한 호겔중첩 방법을 제안한다. 홀로그래픽 프린팅 방법을 이용해 홀로그래픽 스테레오그램을 기록할 때 해상도 증가를 위해 호겔의 크기를 무한정 줄일 수 없음을 컴퓨터 시뮬레이션을 통해 검증한다. 호겔 크기를 줄여 해상도를 증가시키는 방법 대신에 호겔을 중첩 기록시키는 방법을 이용해 홀로그래픽 스테레오그램의 해상도를 증가시킬 수 있는 방법을 제안한다. 홀로그래픽 스테레오그램을 기록할 수 있는 실험환경을 구축하였으며 이를 이용하여 기존의 방법과 제안된 호겔 중첩 방법을 적용한 서로 다른 두 개의 홀로그래픽 스테레오그램을 제작한다. 제작된 두 개의 홀로그래픽 스테레오그램의 재생 영상을 비교함으로써 제안된 호겔중첩 방법을 적용한 홀로그래픽 스테레오그램이 기존의 방법보다 높은 해상도를 가짐을 검증한다. 집적영상을 통해 투명한 특성을 가지는 이차원 및 삼차원 가상영상을 재생할 수 있는 렌즈어레이 홀로그래픽 광학소자를 제안한다. 홀로그래픽 광학소자를 기록하기 위한 실험환경에 파장다중화 기록 방법과 공간다중화 기록방법을 적용하여 총천연색 홀로그램 기록과 대면적 기록을 가능하게 하는 방법에 대해 논한다. 제안된 렌즈어레이 홀로그래픽 광학소자의 특성을 재생실험을 통해 평가한다. 제안된 구조에서 재생된 집적영상을 통해 렌즈어레이 홀로그래픽 광학소자가 증강현실 기술에 적용하기 적합한 광학적으로 투명한 특성을 만족시키면서 총천연색의 삼차원 가상영상을 재생 가능함을 검증한다. 제안된 렌즈어레이 홀로그래픽 광학소자를 통해 재생되는 영상의 관찰특성들을 렌즈어레이 홀로그래픽 광학소자의 광학변수들을 이용하여 평가하며, 이를 이용해 제안된 방법이 이차원/삼차원 투명스크린으로 사용될 수 있는 가능성을 제시한다. 이차원과 삼차원 투명스크린 역할을 할 수 있는 두 개의 서로 다른 사양의 렌즈어레이 홀로그래픽 광학소자들을 제작한다. 이 두 렌즈어레이 홀로그래픽 광학소자들은 재생실험의 결과를 통해 이차원/삼차원 투명 스크린으로 응용할 수 있음을 보이며, 이 때 재생되는 영상들의 관찰 특성들을 평가한다. 또한 외부의 이미지 프로젝터 등의 광변조장치를 통해 제공되는 영상정보를 사용하여 렌즈어레이 홀로그래픽 광학소자 상에서 동적 삼차원 가상영상을 재생하는 방법을 제시한다. 동적 요소영상을 컴퓨터 그래픽스를 이용하여 제작하였으며, 제안된 렌즈어레이 홀로그래픽 광학소자가 동적 삼차원 가상영상을 재생할 수 있음을 실험적으로 검증한다.The novel holographic recording techniques suggested in this dissertation are experimentally investigated to improve the limitations of conventional autostereoscopic three-dimensional (3D) displays. Two types of holographic recording techniques for implementing novel autostereoscopic 3D imaging methods are presented in this dissertation work: i) hogel overlapping method for enhancing lateral resolution of a holographic stereogram, and ii) lens-array holographic optical element (HOE) for providing a see-through property in an integral imaging method. Photopolymer film is used as a holographic material in this work. Dosage responses of a single wavelength and a three-wavelength multiplexed hologram recorded in the photopolymer film are presented. See-through property and diffraction efficiencies of the three-wavelength multiplexed hologram recorded in the photopolymer film are evaluated by the display experiments. Additionally, shrinkage of the photopolymer film is theoretically analyzed and measured by the experiments. The hogel overlapping method for a holographic printing technique is proposed to enhance the lateral resolution of holographic stereograms. A numerical analysis by computer simulation shows that there is a limitation on decreasing the hogel size while recording holographic stereograms. Instead of reducing the size of hogel, the lateral resolution of holographic stereograms can be improved by printing overlapped hogels. An experimental setup for holographic printing is built, and two holographic stereograms using the conventional and proposed overlapping methods are recorded, respectively. The resultant images from the experimentally generated holographic stereograms make a comparison between the conventional and proposed methods. The experimental results confirm that the proposed hogel overlapping method improves the lateral resolution of holographic stereograms compared to the conventional holographic printing method. The lens-array HOE is suggested for a see-through 3D imaging based on the integral imaging. The full-color lens-array HOE provides a see-through property with three-dimensional virtual images. An HOE recording setup is built, and the full-color lens-array HOEs are recorded by using holographic recording techniques of a spatial and wavelength multiplexing. The experimental results confirm that the suggested method can provide the full-color 3D virtual images with the see-through property. The viewing characteristics of the presented autostereoscopic 3D display are evaluated by the optical parameters of the lens-array HOE. Two lens-array HOEs with different optical parameters are fabricated to have both functions of the two-dimensional (2D) and 3D transparent screens. Display experiments for the 2D and 3D imaging on the proposed transparent screens are carried out, and the viewing characteristics in both cases are discussed. The autostereoscopic 3D display using the lens-array HOE can provide dynamic 3D virtual images because it has an external spatial light modulator. The dynamic elemental images are generated by computer graphics, and the feasibility of displaying the dynamic 3D virtual images on the lens-array HOE is experimentally verified.Chapter 1 Introduction 1 1.1 Background and current issues of autostereoscopic three-dimensional display 1 1.2 Motivation of this dissertation work 8 1.3 Objective and scope of this dissertation 11 Chapter 2 Photopolymer film for holographic material 14 2.1 Introduction 14 2.2 Principles of refractive index modulation in photopolymer film 18 2.3 Dosage response of photopolymer film for the hologram recording in a reflection geometry 23 2.4 Shrinkage characteristic of photopolymer film 37 2.5 Results 45 Chapter 3 High resolution autostereoscopic 3D display using holographic printing 47 3.1 Introduction 47 3.2 Overview of holographic printing method 49 3.3 Limitation on enhancing lateral resolution of holographic printing 54 3.4 Hogel overlapping method for enhancing lateral resolution of holographic printer 60 3.5 Experiments 64 3.6 Results 71 Chapter 4 See-through autostereoscopic 3D display using lens-array holographic optical elements 73 4.1 Introduction 73 4.2 Full-color lens-array holographic optical elements for displaying integral images 77 4.2.1 Principles of full-color lens-array holographic optical elements 77 4.2.2 Hologram recording setup for fabricating proposed lens-array holographic optical elements 80 4.2.3 Three-dimensional imaging on full-color lens-array holographic optical elements 85 4.3 Viewing characteristic analysis on lens-array holographic optical elements 90 4.3.1 Viewing characteristic of lens-array holographic optical elements 91 4.3.2 2D and 3D imaging on lens-array holographic optical elements with different viewing parameters 94 4.3.3 Experiments 98 4.4 Dynamic autostereoscopic 3D images displayed on the lens-array HOE 109 4.5 Results 113 Chapter 5 Conclusion and recommendation for future work 115 5.1 Conclusion 115 5.2 Recommendation for future work 120 Bibliography 124 Appendix 138 초 록 139Docto

Caracteritzación de una sala de cine para la proyección de películas en 3D

El Trabajo se centra en caracterizar la sala comercial de proyección de películas en 3D con la pantalla más grande de Catalunya. Nos proponemos caracterizar geométricamente la sala y describir el sistema de proyección que utiliza. Para relacionarlo con la optometría se definirá un observador promedio, del cual tomaremos su rango de la Zona de Visión Binocular Simple y Nítida para obtener, mediante los criterios de Sheard y Pércival, la zona de visión cómoda, y extrapolarlo a la separación entre imágenes de los estímulos monoculares sobre la pantalla y la distancia a la que se percibirá el estímulo. A través del área de ZVBSN del observador patrón también evaluaremos qué supone para la proyección del estímulo el límite de visión simple y nítida. También se evalúa la influencia de la DIP en la percepción del estímulo 3D y la variación de la convergencia requerida según la posición del observador. Todos estos análisis se hacen para distintas butacas características de la sala. También se describe en el trabajo la distribución de la luminosidad de la sala en distintas condiciones de proyección. Finalmente, después ordenar y evaluar una gran cantidad de datos hemos podido constatar que cuanto menor es la distancia entre el observador y el estímulo, mayor es el requerimiento de convergencia. Otro aspecto que hemos podido corroborar es que variar la posición del estímulo en la pantalla repercute sobre la convergencia requerida. En cuanto a la relevancia de la DIP, cuanto más pequeña, menor esfuerzo de convergencia se necesita para fijar un mismo punto y a medida que la DIP aumenta, la distancia a la que se percibe la imagen se aleja. La posición en la sala no es determinante en cuanto a la percepción de la distancia a la que percibirá el estímulo. En cuanto al estímulo, un incremento de la distancia de desdoblamiento entre las imágenes monoculares produce un aumento de la espectacularidad del estímulo y exige una demanda de convergencia superio

Remote Visual Observation of Real Places Through Virtual Reality Headsets

Virtual Reality has always represented a fascinating yet powerful opportunity that has attracted studies and technology developments, especially since the latest release on the market of powerful high-resolution and wide field-of-view VR headsets. While the great potential of such VR systems is common and accepted knowledge, issues remain related to how to design systems and setups capable of fully exploiting the latest hardware advances. The aim of the proposed research is to study and understand how to increase the perceived level of realism and sense of presence when remotely observing real places through VR headset displays. Hence, to produce a set of guidelines that give directions to system designers about how to optimize the display-camera setup to enhance performance, focusing on remote visual observation of real places. The outcome of this investigation represents unique knowledge that is believed to be very beneficial for better VR headset designs towards improved remote observation systems. To achieve the proposed goal, this thesis presents a thorough investigation of existing literature and previous researches, which is carried out systematically to identify the most important factors ruling realism, depth perception, comfort, and sense of presence in VR headset observation. Once identified, these factors are further discussed and assessed through a series of experiments and usability studies, based on a predefined set of research questions. More specifically, the role of familiarity with the observed place, the role of the environment characteristics shown to the viewer, and the role of the display used for the remote observation of the virtual environment are further investigated. To gain more insights, two usability studies are proposed with the aim of defining guidelines and best practices. The main outcomes from the two studies demonstrate that test users can experience an enhanced realistic observation when natural features, higher resolution displays, natural illumination, and high image contrast are used in Mobile VR. In terms of comfort, simple scene layouts and relaxing environments are considered ideal to reduce visual fatigue and eye strain. Furthermore, sense of presence increases when observed environments induce strong emotions, and depth perception improves in VR when several monocular cues such as lights and shadows are combined with binocular depth cues. Based on these results, this investigation then presents a focused evaluation on the outcomes and introduces an innovative eye-adapted High Dynamic Range (HDR) approach, which the author believes to be of great improvement in the context of remote observation when combined with eye-tracked VR headsets. Within this purpose, a third user study is proposed to compare static HDR and eye-adapted HDR observation in VR, to assess that the latter can improve realism, depth perception, sense of presence, and in certain cases even comfort. Results from this last study confirmed the author expectations, proving that eye-adapted HDR and eye tracking should be used to achieve best visual performances for remote observation in modern VR systems

Journal of Telecommunications and Information Technology, 2014, nr 1

kwartalni

Quality of Experience in Immersive Video Technologies

Over the last decades, several technological revolutions have impacted the television industry, such as the shifts from black & white to color and from standard to high-definition. Nevertheless, further considerable improvements can still be achieved to provide a better multimedia experience, for example with ultra-high-definition, high dynamic range & wide color gamut, or 3D. These so-called immersive technologies aim at providing better, more realistic, and emotionally stronger experiences. To measure quality of experience (QoE), subjective evaluation is the ultimate means since it relies on a pool of human subjects. However, reliable and meaningful results can only be obtained if experiments are properly designed and conducted following a strict methodology. In this thesis, we build a rigorous framework for subjective evaluation of new types of image and video content. We propose different procedures and analysis tools for measuring QoE in immersive technologies. As immersive technologies capture more information than conventional technologies, they have the ability to provide more details, enhanced depth perception, as well as better color, contrast, and brightness. To measure the impact of immersive technologies on the viewersâ QoE, we apply the proposed framework for designing experiments and analyzing collected subjectsâ ratings. We also analyze eye movements to study human visual attention during immersive content playback. Since immersive content carries more information than conventional content, efficient compression algorithms are needed for storage and transmission using existing infrastructures. To determine the required bandwidth for high-quality transmission of immersive content, we use the proposed framework to conduct meticulous evaluations of recent image and video codecs in the context of immersive technologies. Subjective evaluation is time consuming, expensive, and is not always feasible. Consequently, researchers have developed objective metrics to automatically predict quality. To measure the performance of objective metrics in assessing immersive content quality, we perform several in-depth benchmarks of state-of-the-art and commonly used objective metrics. For this aim, we use ground truth quality scores, which are collected under our subjective evaluation framework. To improve QoE, we propose different systems for stereoscopic and autostereoscopic 3D displays in particular. The proposed systems can help reducing the artifacts generated at the visualization stage, which impact picture quality, depth quality, and visual comfort. To demonstrate the effectiveness of these systems, we use the proposed framework to measure viewersâ preference between these systems and standard 2D & 3D modes. In summary, this thesis tackles the problems of measuring, predicting, and improving QoE in immersive technologies. To address these problems, we build a rigorous framework and we apply it through several in-depth investigations. We put essential concepts of multimedia QoE under this framework. These concepts not only are of fundamental nature, but also have shown their impact in very practical applications. In particular, the JPEG, MPEG, and VCEG standardization bodies have adopted these concepts to select technologies that were proposed for standardization and to validate the resulting standards in terms of compression efficiency