Lossy compression algorithms used in digital video systems produce artifacts whose visibility strongly depends on the actual image content. Simple error measures such as RMSE or PSNR, albeit popular, ignore this important fact and are only a mediocre predictor of perceived quality. Many applications require more reliable assessment methods. This paper discusses issues in vision modeling for perceptual video quality assessment (PVQA). Its purpose is not to describe a particular model or system, but rather to summarize and to provide pointers to up-to-date knowledge of important characteristics of the human visual system, to explain how these characteristics may be incorporated in vision models for PVQA, to give a brief overview of the state-of-the-art and current efforts in this field, and to outline directions for future research.

Groups collaborating around a large wall display can do so in a variety of arrangements, positioning themselves at different distances from the display and from each other. We examined the impact of proximity on the effectiveness and enjoyment of colocated collaboration. Our results revealed collaborative benefits when participants were positioned close together, and interaction with the display was felt to be more effective when participants were close to the display. However, clear tradeoffs were evident for these configurations. When at a distance to the display, the choice of direct versus indirect interaction revealed that interactions were easier when using direct input but the effectiveness of the collaboration was compromised.

With recent advances in technology, large wall-sized displays are becoming prevalent. Although researchers have articulated qualitative benefits of large displays, little has been done to systematically quantify and exploit these benefits. Additionally, since most researchers have assumed that larger displays fill a greater percentage of the viewer’s visual field, physical size is often confused with visual angle, or field of view. In my thesis, I will first isolate the effects that physical size has on the way users react to information. I will then show how we can exploit these reactions to construct display systems that make users more productive than they were on traditional systems. In this proposal, I describe work I have done to compare the performance of users working on large wall-sized displays to that of users working on smaller displays, viewed at identical visual angles. In the first set of studies, I show that although there was no significant difference in performance on a reading comprehension task, users performed 26 % better on a spatial orientation task done on a large display. Results suggest that these improvements can be attributed to the large display affording a greater sense of presence and biasing users into treating the spatial task as an egocentric rather than an exocentric rotation. In a second study, I apply an implicit memory paradigm to measure whether or not someone has read a