document

Lighting to make you feel better: Improving the mood of elderly people with affective ambiences

Kuijsters, A. (author), Redi, J.A. (author), De Ruyter, B. (author), Heynderickx, I.E.J.R. (author)

Current lighting technologies extend the options for changing the appearance of rooms and closed spaces, as such creating ambiences with an affective meaning. Using intelligence, these ambiences may instantly be adapted to the needs of the room’s occupant(s), possibly improving their well-being. We hypothesized that ambiences with a clearly...

journal article 2015

document

Virtual bystanders in a language lesson: Examining the effect of social evaluation, vicarious experience, cognitive consistency and praising on students' beliefs, self-efficacy and anxiety in a virtual reality environment

Qu, C. (author), Ling, Y. (author), Heynderickx, I. (author), Brinkman, W.P. (author)

Bystanders in a real world's social setting have the ability to influence people’s beliefs and behavior. This study examines whether this effect can be recreated in a virtual environment, by exposing people to virtual bystanders in a classroom setting. Participants (n = 26) first witnessed virtual students answering questions from an English...

journal article 2015

document

Towards a comprehensive model for predicting the quality of individual visual experience

Zhu, Y. (author), Heynderickx, I.E.J.R. (author), Hanjalic, A. (author), Redi, J.A. (author)

Recently, a lot of effort has been devoted to estimating the Quality of Visual Experience (QoVE) in order to optimize video delivery to the user. For many decades, existing objective metrics mainly focused on estimating the perceived quality of a video, i.e., the extent to which artifacts due to e.g. compression disrupt the appearance of the...

conference paper 2015

document

Human discrimination of depth of field in stereoscopic and nonstereoscopic photographs

Zhang, T. (author), Nefs, H.T. (author), Heynderickx, I.E.J.R. (author)

Depth of field (DOF) is defined as the distance range within which objects are perceived as sharp. Previous research has focused on blur discrimination in artificial stimuli and natural photographs. The discrimination of DOF, however, has received less attention. Since DOF introduces blur which is related to distance in depth, many levels of...

journal article 2014

document

The effect of applying 2D enhancement algorithms on 3D video content

Wu, S.L. (author), Caviedes, J.E. (author), Karam, L. (author), Heynderickx, I.E.J.R. (author)

Enhancement algorithms are typically applied to video content to increase their appeal to viewers. Such algorithms are readily available in the literature and are already widely applied in, for example, commercially available TVs. On the contrary, not much research has been done on enhancing stereoscopic 3D video content. In this paper, we...

journal article 2014

document

A Meta-Analysis on the Relationship between Self-Reported Presence and Anxiety in Virtual Reality Exposure Therapy for Anxiety Disorders

Ling, Y. (author), Nefs, H.T. (author), Nexhmedin, M. (author), Heynderickx, I. (author), Brinkman, W.P. (author)

In virtual reality exposure therapy (VRET) for anxiety disorders, sense of presence in the virtual environment is considered the principal mechanism that enables anxiety to be felt. Existing studies on the relation between sense of presence and level of anxiety, however, have yielded mixed results on the correlation between the two. In this meta...

journal article 2014

document

Alone or together: Measuring users' viewing experience in different social contexts

Zhu, Y. (author), Heynderickx, I. (author), Redi, J.A. (author)

In the past decades, a lot of effort has been invested in predicting the users’ Quality of Visual Experience (QoVE) in order to optimize online video delivery. So far, the objective approaches to measure QoVE have been mainly based on an estimation of the visibility of artifacts generated by signal impairments at the moment of delivery and on a...

conference paper 2014

document

The effect of perspective on presence and space perception

Ling, Y. (author), Nefs, H.T. (author), Brinkman, W.P. (author), Qu, C. (author), Heynderickx, I. (author)

In this paper we report two experiments in which the effect of perspective projection on presence and space perception was investigated. In Experiment 1, participants were asked to score a presence questionnaire when looking at a virtual classroom. We manipulated the vantage point, the viewing mode (binocular versus monocular viewing), the...

journal article 2013

document

Studying the effect of optimizing image quality in salient regions at the expense of background content

Alers, H. (author), Redi, J. (author), Liu, H. (author), Heynderickx, I. (author)

Manufacturers of commercial display devices continuously try to improve the perceived image quality of their products. By applying postprocessing techniques on the incoming signal, they aim to enhance the quality level perceived by the viewer. These postprocessing techniques are usually applied globally over the whole image but may cause side...

journal article 2013

document

Studying the relative impact of ghosting and noise on the perceived quality of MR images

Liu, H. (author), Koonen, J. (author), Fuderer, M. (author), Heynderickx, I. (author)

In current magnetic resonance (MR) imaging systems, design choices are confronted with a trade-off between structured (i.e. artifacts) and unstructured noise. The impact of both types of noise on perceived image quality, however, is so far unknown, while this knowledge would be highly beneficial for further improvement of MR imaging systems. In...

conference paper 2012

document

Interactions of visual attention and quality perception

Redi, J.A. (author), Liu, H. (author), Zunino, R. (author), Heynderickx, I.E.J.R. (author)

Several attempts to integrate visual saliency information in quality metrics are described in literature, albeit with contradictory results. The way saliency is integrated in quality metrics should reflect the mechanisms underlying the interaction between image quality assessment and visual attention. This interaction is actually two-fold: (1)...

journal article 2011

document

Efficient neural-network-based no-reference approach to an overall quality metric for JPEG and JPEG2000 compressed images

Liu, H. (author), Redi, J.A. (author), Alers, H. (author), Zunino, R. (author), Heynderickx, I.E.J.R. (author)

Reliably assessing overall quality of JPEG/JPEG2000 coded images without having the original image as a reference is still challenging, mainly due to our limited understanding of how humans combine the various perceived artifacts to an overall quality judgment. A known approach to avoid the explicit simulation of human assessment of overall...

journal article 2011

document

Issues in the design of a no-reference metric for perceived blur

Liu, H. (author), Heynderickx, I. (author)

Developing an objective metric, which automatically quantifies perceived image quality degradation induced by blur, is highly beneficial for current digital imaging systems. In many applications, these objective metrics need to be of the noreference (NR) type, which implies that quality prediction is based on the distorted image only. Recent...

journal article 2011

document

Cybersickness and anxiety in virtual environments

Ling, Y. (author), Brinkman, W.P. (author), Nefs, H.T. (author), Qu, C. (author), Heynderickx, I.E.J.R. (author)

The question whether feelings of anxiety are confounded with cybersickness in studies on virtual reality exposure therapy (VRET) was raised since the questionnaires used to measure them contain overlapping items. In the experiment, 88 participants were asked to talk in front of a virtual audience. Previous research has shown that this task may...

conference paper 2011

document

Improving the mood of elderly with coloured lighting

Kuijsters, A. (author), Redi, J.A. (author), De Ruyter, B. (author), Heynderickx, I.E.J.R. (author)

The ACE project aims at developing an adaptive ambience creation platform which can improve the well-being of elderly people in care centers. The system will contain a sensing platform, which measures and analyses the context in a room and an ambience creation platform, which creates ambiences with proven effectiveness for improving the mood of...

conference paper 2011

document

Issues in the design of a no-reference metric for perceived blur

Liu, H. (author), Heynderickx, I. (author)

Developing an objective metric, which automatically quantifies perceived image quality degradation induced by blur, is highly beneficial for current digital imaging systems. In many applications, these objective metrics need to be of the noreference (NR) type, which implies that quality prediction is based on the distorted image only. Recent...

conference paper 2010

document

Studying the effect of optimizing the image quality in saliency regions at the expense of background content

Alers, H. (author), Liu, H. (author), Redi, J. (author), Heynderickx, I. (author)

Manufacturers of commercial display devices continuously try to improve the perceived image quality of their products. By applying some post processing techniques on the incoming image signal, they aim to enhance the quality level perceived by the viewer. Applying such techniques may cause side effects on different portions of the processed...

conference paper 2010

document

Comparing subjective image quality measurement methods for the creation of public databases

Redi, J. (author), Liu, H. (author), Alers, H. (author), Zunino, R. (author), Heynderickx, I. (author)

conference paper 2010

document

A Perceptually Relevant No-Reference Blockiness Metric Based on Local Image Characteristics

Liu, H. (author), Heynderickx, I. (author)

A novel no-reference blockiness metric that provides a quantitative measure of blocking annoyance in block-based DCT coding is presented. The metric incorporates properties of the human visual system (HVS) to improve its reliability, while the additional cost introduced by the HVS is minimized to ensure its use for real-time processing. This is...

journal article 2009

document

Perceptually optimal boundaries for wide gamut TVs

laird, J. (author), Heynderickx, I. (author)

Displays are coming on the market that can produce a larger range of colors over EBU and this has led to much research on the topic of how to use the additional color gamut volume provided by the displays. Some research has focused on different methods to map colors from small to large gamuts, whereas this paper focuses on defining the required...

conference paper 2008