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Publications

Publications by Maximino Bessa

2015

Screen reflections impact on HDR video tone mapping for mobile devices: an evaluation study

Authors
Melo, M; Bessa, M; Barbosa, L; Debattista, K; Chalmers, A;

Publication
EURASIP JOURNAL ON IMAGE AND VIDEO PROCESSING

Abstract
This paper presents an evaluation of high-dynamic-range (HDR) video tone mapping on a small screen device (SSD) under reflections. Reflections are common on mobile devices as these devices are predominantly used on the go. With this evaluation, we study the impact of reflections on the screen and how different HDR video tone mapping operators (TMOs) perform under reflective conditions as well as understand if there is a need to develop a new or hybrid TMO that can deal with reflections better. Two well-known HDR video TMOs were evaluated in order to test their performance with and without on-screen reflections. Ninety participants were asked to rank the TMOs for a number of tone-mapped HDR video sequences on an SSD against a reference HDR display. The results show that the greater the area exposed to reflections, the larger the negative impact on a TMO's perceptual accuracy. The results also show that under observed conditions, when reflections are present, the hybrid TMOs do not perform better than the standard TMOs.

2016

Usability evaluation of an entertainment platform by people with intellectual disabilities

Authors
Rocha, T; Carvalho, D; Gonçalves, R; Martins, J; Branco, F; Bessa, M;

Publication
2016 11TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI)

Abstract
In this paper it is presented a usability evaluation of an entertainment platform, well-known, YouTube. The main aim is to study how people with intellectual disabilities interact with the layout and uses their search field option. We intended to observe and analyze performance and satisfaction but also if the interface can give them autonomy on the search option. The results show that participants had a good experience with the interface, however cannot be autonomy with the search option.

2014

Corner Based Many-Objective Optimization

Authors
Freire, H; de Moura Oliveira, PBD; Solteiro Pires, EJS; Bessa, M;

Publication
NATURE INSPIRED COOPERATIVE STRATEGIES FOR OPTIMIZATION (NICSO 2013)

Abstract
The performance of multi-objective evolutionary algorithms (MOEA) is severely deteriorated when applied to many-objective problems. For Pareto dominance based techniques, available information about optimal solutions can be used to improve their performance. This is the case of corner solutions. This work considers the behaviour of three multi-objective algorithms (NSGA-II, SMPSO and GDE3) when corner solutions are inserted into the population at different evolutionary stages. Corner solutions are found using specific algorithms. Preliminary results are presented concerning the behaviour of the aforementioned algorithms in five benchmark problems (DTLZ1-5).

2013

Digital Services in Immersive Urban Virtual Environments

Authors
Meira, C; Freitas, J; Barbosa, L; Melo, M; Bessa, M; Magalhaes, L;

Publication
PROCEEDINGS OF THE 2013 8TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI 2013)

Abstract
Virtual Environments (VE) systems may provide a new way to deliver information and services in many areas, for example in tourism, urban planning and education. In urban VE there is a close link between the virtual environment and the urban environment that are intended to represent. These VE can be an intuitive way to access a set of services with a direct association to the real object or entity to which they are related. In this article, we describe a case study that aimed at exploring the possibility of using new interfaces to exploit and use services in urban VE with a greater sense of immersiveness. The results indicate that the VE interfaces are a natural and intuitive access to digital services. While users have felt a greater difficulty in performing some of the tasks in immersive scenario, the majority considered that this scenario provided a greater sense of immersion and realism.

2013

Minimum image quality assessment based on saliency maps: a human visual approach

Authors
Barreira, J; Bessa, M; Magalhaes, L;

Publication
IMAGE QUALITY AND SYSTEM PERFORMANCE X

Abstract
Image quality assessment as perceived by humans is of crucial importance in numerous fields of image processing. Transmission and storage of digital media require efficient methods to reduce the large number of bits to store an image, while maintaining sufficiently high quality compared to the original image. Since subjective evaluations cannot be performed in various scenarios, it is necessary to have objective metrics that predict image quality consistent with human perception. However, objective metrics that considers high levels of the human visual system are still limited. In this paper, we investigate the possibility of automatically predict, based on saliency maps, the minimum image quality threshold from which humans can perceive the elements on a compressed image. We conducted a series of experimental subjective tests where human observers have been exposed to compressed images with decreasing compression rates. To measure the difference between the saliency maps of the compressed and the original image it was used the normalized absolute error metric. Our results indicate that the elements on the image are only perceived by most of the human subjects not at a specific compressed image quality level, but depending on a saliency map difference threshold.

2017

Context-aware HDR video distribution for mobile devices

Authors
Melo, M; Barbosa, L; Bessa, M; Debattista, K; Chalmers, A;

Publication
MULTIMEDIA TOOLS AND APPLICATIONS

Abstract
HDR video on mobile devices is in its infancy and there are no solutions yet that can achieve full HDR video reproduction due to computational power limitations. In this paper we present a novel and versatile solution that allows the delivery of HDR video on mobile devices by taking into account contextual information and retro-compatibility for devices that do not have the computational power to decode HDR video. The proposed solution also enables the remote transmission of HDR video to mobile devices in real-time. This context-aware HDR video distribution solution for mobile devices is evaluated and discussed by considering the impact of HDR videos over conventional low dynamic range videos on mobile devices as well as the challenge of playing HDR videos directly locally or remotely.

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