Abstract
Prior to having available the High Dynamic Range (HDR) techniques, certain levels of luminance could only by captured by the human eye. Currently, HDR technology overcomes the limitations of conventional imaging technology (also referred as Low Dynamic Range or LDR) and allows the capture and delivery of contents that can match the dynamic range of the real world. However, the state of the art of HDR video focus mainly on conventional sized displays typical of TVs or PCs. As the usage of mobile devices for multimedia consumption is increasing considerably, there is a need for studying the impact of the viewing of HDR video on such devices. This will allow to take full advantage of HDR technology, creating a set of opportunities for the digital business as it allows, among others, the presentation of products in a much more efficient and captivating way. On this paper it is presented a study that evaluates the impact of the HDR video delivery on mobile devices and compares it with the impact of Low Dynamic Range (LDR) content. Results show that the delivery of HDR video on mobiles is possible without requiring much more resources when comparing the delivery of LDR video.

Abstract
In the last three decades with the Information Technologies advent and the growth of the concept of Virtual Environments, a set of new ways to perform tasks have emerged, in the most diversified areas of society. The main focus of this work was to verify if it was possible to increase the sense of presence through multi-sensory stimulation, creating a virtual environment of simulation that causes stress in exposure therapy, in this case in people who have a fear of heights. The evaluation of the sense of presence was made using the Portuguese version of a previously validated IPQ (Igroup Presence Questionnaire) and also through direct observation of the movements caused by oculomotor reflexes. Although the achievement results that were not very significant between the two tested groups, the multisensory simulation environment obtained better results in terms of involvement in relation to space and realism, which increased concentration in the experience. The obtained results seem to indicate that the alone addition of further stimuli does not lead to an increased feeling of presence, therefore existing the need to understand which are the critical stimuli for each assessment situation.

Abstract
A number of High Dynamic Range (HDR) video compression algorithms proposed to date have either been developed in isolation or only-partially compared with each other. Previous evaluations were conducted using quality assessment error metrics, which for the most part were developed for qualitative assessment of Low Dynamic Range (LDR) videos. This paper presents a comprehensive objective and subjective evaluation conducted with six published HDR video compression algorithms. The objective evaluation was undertaken on a large set of 39 HDR video sequences using seven numerical error metrics namely: PSNR, logPSNR, puPSNR, puSSIM, Weber MSE, HDR-VDP and HDR-VQM. The subjective evaluation involved six short-listed sequences and two ranking-based subjective experiments with hidden reference at two different output bitrates with 32 participants each, who were tasked to rank distorted HDR video footage compared to an uncompressed version of the same footage. Results suggest a strong correlation between the objective and subjective evaluation. Also, non-backward compatible compression algorithms appear to perform better at lower output bit rates than backward compatible algorithms across the settings used in this evaluation.

Abstract
With this study we aim at assessing if a mini iPad device is a usable option for digital interaction to perform selection, manipulation, and insertion tasks by people with intellectual disabilities. This study builds on previous studies where usability was evaluated for universal tasks using the keyboard and a mouse input device [1]. This allowed us to assess the usability of a small mini iPad and compare it with other two input devices, namely keyboards and the mouse. For usability assessment we registered the following variables: successful conclusion of activities, type of difficulties found, errors and satisfaction indicators. The results showed that this group was much motivated to learn how to handle with the iPad, several asked to repeat the task and no one quit any task requested. Despite the number of errors as registered in their interaction, they always knew how to overcome the error and never showed frustration or demotivation. Furthermore, they had a good performance (relation between variables: time to conclude the task, number of errors and difficulties felt) with the mini iPad device, however when compared with the keyboard and mouse, their performance increased. © 2016 ACM.

Abstract
The sense of presence and cybersickness are keyfactors to have into account when referring to Virtual Environments (VE). To achieve high levels of presence and minimize cybersickness, it is important to ensure that the user's stimulation is coherent with the contents that are being delivered. In this paper, it is presented a pilot study addressing the usage of both objective and subjective metrics to measure the sense of presence and cybersickness in VE in order to study possible correlations between these two evaluation approaches. On top of that, the pilot study includes two body positions to allow evaluating if the stimulation of the vestibular study has impact on the sense of presence and cybersickness. To evaluate presence and cybersickness, it was developed a VE that consists in a hill where participants ride a bicycle. To broaden the scope of the study, there were studied two body positions: standing and sitting on the bicycle. The equipment EMOTIV epoc+ was used to register the objective metrics. The subjective metrics were registered using the Igroup Presence Questionnaire (IPQ) and the Simulator Sickness Questionnaire (SSQ). To complement the collected data, the levels of fatigue and stress before and after the experience were also registered through self-evaluation. Results show that objective metrics Interest and Stress and the subjective metrics Realism, Fatigue and Stress have a positive interaction regarding the sense of presence. Results further suggest that there is a positive interaction between the objective metric Focus and the subjective metric Involvement.

Abstract
In this paper an accessible Web application that uses icons instead of text to performed YouTube video search, called SAMi, is presented. With this iconic interaction Web application (SAMi), we aimed to develop universal access on the Web, by presenting an alternative way of Web search (without using text); to be a starting point for the definition of an accessible interaction metaphor, based on universal design iconography for digital environments; and ultimately, to contribute to the democratization of access to the Web for all users, regardless of the degree of literacy. The main results obtained with the user test evaluation were: first-rate performance, higher satisfaction and total autonomy in their interaction with SAMi.