Abstract
Virtual Reality (VR) has as a key feature, the users’ interaction with a virtual environment. Depending on the purpose of a given VR application, it can be essential to use multisensory stimulus without biasing users towards specific actions or decisions in the virtual environment (VE). The goal of the present work is to study if the choice of paths can be influenced by the addition of multisensory stimulus when navigating in a VE using an immersive setup. The awareness of having to take such decisions was also considered. For the purpose, we used a VR game-like application contemplating three levels. Each level was symmetrical and had two possible paths to move to the next level (left or right). For each level, there was a multisensory stimulus on the right path (from a subject orientation): wind, vibration, scent respectively. The sample of the study consisted of 50 participants, and the results showed that none of the multisensory stimuli had a significant impact users’ decision. The users’ awareness of having to decide also did not affect their path. We conclude that multisensory stimuli can be used to raise the credibility of the virtual environments without compromising the users’ decisions. © Springer Nature Switzerland AG 2019.

Abstract
Recently, there has been a significant progress in the research and development of the high dynamic range (HDR) video technology and the state-of-the-art video pipelines are able to offer a higher bit depth support to capture, store, encode, and display HDR video content. In this paper, we introduce a novel HDR video compression algorithm, which uses a perceptually uniform color opponent space, a novel perceptual transfer function to encode the dynamic range of the scene, and a novel error minimization scheme for accurate chroma reproduction. The proposed algorithm was objectively and subjectively evaluated against four state-of-the-art algorithms. The objective evaluation was conducted across a set of 39 HDR video sequences, using the latest x265 10-bit video codec along with several perceptual and structural quality assessment metrics at 11 different quality levels. Furthermore, a rating-based subjective evaluation (n = 40) was conducted with six sequences at two different output bitrates. Results suggest that the proposed algorithm exhibits the lowest coding error amongst the five algorithms evaluated. Additionally, the rate-distortion characteristics suggest that the proposed algorithm outperforms the existing state-of-the-art at bitrates >= 0.4 bits/pixel.

Abstract
Consumer High Dynamic Range (HDR) displays are appearing on the market. Capable of generating a peak luminance of up to 2,000 nits, the improved dynamic range they provide can only be perceived when viewed in a dark environment. In this paper, we present a display architecture that is capable of generating a peak luminance of 10,000 nits. We demonstrate, with a subjective evaluation, that the increased peak luminance is required to perceive a high dynamic range in bright ambient environments. Furthermore, we show that by fitting a surface through the data, we can predict the dynamic range that can be perceived from the luminance and illuminance with low error. We can also invert the prediction to estimate the required peak luminance for a particular combination of dynamic range and ambient lighting.

Abstract
High dynamic range (HDR) displays are capable of displaying a wider dynamic range of values than conventional displays. As HDR content becomes more ubiquitous, the use of these displays is likely to accelerate. As HDR displays can present a wider range of values, traditional strategies for mapping HDR content to low dynamic range (LDR) displays can be replaced with either directly displaying values, or using a simple shift mapping (exposure adjustment). The latter approach is especially important when considering ambient lighting, as content viewed in a dark environment may appear substantially different to a bright one. This paper seeks to identify an exposure value which is suitable for displaying specific HDR content on an HDR display under a range of ambient lighting levels. Based on data captured with human participants, this paper establishes user preferred exposure values for a variety of maximum display brightnesses, content and ambient lighting levels. These are then used to develop two models to predict preferred exposure. The first is based on linear regression using straightforward image statistics which require minimal computation and memory to be computed, making this method suitable to be directly used in display hardware. The second is a model based on convolutional neural networks (CNN) to learn image features which best predict exposure values. The CNN model generates better results than the first model at the cost of memory and computation time.

Abstract
Among the wide application areas that Virtual Reality (VR) can have a major impact, one is Education. However, this potential is still unexplored, and one of these gaps has to do with language learning. Listening activities, which are often only supported by audio, are thought of to be demanding area when it comes to learning a second or foreign language and so therefore an interesting area for VR to take place. This pilot study therefore presents the perceptions of foreign language teachers regarding a novel medium for delivering listening activities to their students: Virtual Reality technology. The results show that foreign language teachers are of the opinion that this technology can help motivate students and potentiate the student’s learning curve regarding the listening of a foreign or second language. © Springer Nature Switzerland AG 2019.

Abstract
There are still open questions about the effectiveness of Virtual Reality (VR) in Education when compared to conventional learning methods. This paper studies the feasibility of a VR-based learning tool and the possible differences in knowledge retention across a VR learning method and a conventional audio method, when it comes to learning a foreign language. Also, the students’ sense of presence and satisfaction were studied. For such purpose, a user study was conducted and results revealed that while presence and satisfaction were higher in Virtual Reality, the knowledge retention score remains the same across both experimental conditions. © Springer Nature Switzerland AG 2019.