ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / Aerial image collections have experienced exponential growth in size in recent years. These high resolution images are often viewed at a variety of scales. When an image is displayed at reduced scale, maximum quantization step sizes for visually lossless quality become larger. However, previous visually lossless coding algorithms quantize the image with a single set of quantization step sizes, optimized for display at the full resolution level. This implies that if the image is rendered at reduced resolution, there are significant amounts of extraneous information in the codestream. Thus, in this paper, we propose a method which effectively incorporates multiple quantization step sizes, for various display resolutions, into the JPEG2000 framework. If images are browsed from a remote location, this method can significantly reduce bandwidth usage by only transmitting the portion of the codestream required for visually lossless reconstruction at the desired resolution. Experimental results for high resolution color aerial images are presented.

ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper describes a psychophysical experiment to measure visibility thresholds (VT) for quantization distortion in JPEG2000 and an associated quantization algorithm for visually lossless coding of color aerial images. The visibility thresholds are obtained from a quantization distortion model based on the statistical characteristics of wavelet coefficients and the deadzone quantizer of JPEG2000, and the resulting visibility thresholds are presented for the luminance component (Y) and two chrominance components (Cb and Cr). Using the thresholds, we have achieved visually lossless coding for 24-bit color aerial images at an average bitrate of 4.17 bits/pixels, which is approximately 30% of the bitrate required for numerically lossless coding.

Accessibility is important in the development of digital products as well as in physical products. An accessible product enables all people to use it, whether they have a disability or not. This thesis focuses on accessibility for visually impaired people in a music streaming service on desktop. Many music streaming services for desktop are built with web technologies, including Spotify. The aim of this thesis was to evaluate the accessibility status of the Spo- tify desktop application as well as develop accessibility guidelines fo- cused on a music streaming service. A user test was performed to in- vestigate the accessibility status of the desktop application. Existing accessibility guidelines was studied and used together with the results of the user test to develop accessibility guidelines applicable to a music streaming service. It was found that the Spotify desktop application had many accessibility issues and these were considered when developing accessibility guide- lines. The existing guidelines studied was the WCAG 2.0 guidelines developed by W3C. These were read through completely and compiled in Chapter 4 of this report. The result of the thesis was accessibility guidelines suitable for a music streaming service on desktop. Since music streaming applications can be developed using different techniques and frameworks these guide- lines should be used as a guide on how to implement accessibility and needs to be customized for each use case. Though the fundamentals of the guidelines should be applicable to most music streaming desktop applications.

<p>Interacting with the world is a two-step process of accurate sensing followed by coordinated movement. Optimization of biologically-inspired robotic systems benefits from the quantification and modeling of natural sensorimotor behavior, including the bottom-up circuits that mediate it and top-down cognitive influences that modulate it. A critical sensorimotor behavior in everyday life is the generation of rapid eye movements, called saccades. By making saccades 2-3 times/second, we scan visual scenes and integrate the incoming visual signals to construct an internal representation of what is around us. Much is still unknown about the neural processes that act on visual input and the nature of the resulting internal construct. To study this, we first created a model with architecture inspired by known visuomotor circuits in the brain. By training the model to achieve visuomotor stability while varying its visual and motor inputs, we found that it converged onto a solution that resembled and explained a dynamic neural process that had been documented electrophysiologically. Second, in a psychophysical experiment, we kept constant the visual stimuli and motor actions but manipulated the expectations of what subjects thought would happen. We found that visual perception systematically changes based on expectation, providing evidence for cognitive influences on visuomotor integration and continuity. Third, we expanded the work to whole-body orienting in an immersive virtual environment. While performing a marksmanship task, subjects learned to precisely intercept moving targets. Analysis and modeling of the dynamics of movement revealed mechanisms of learning in this realistic behavioral context. Taken together, the studies provide a link between the ensemble activity of neurons and perceptual experience, demonstrate that perception is a combination of incoming signals and prior beliefs, and move the field toward the study of perception-action cycles during natural human behavior.</p> / Dissertation

This dissertation presents work towards the development of a multiple finger, worn, dynamic display device, which utilizes a method of texture encoded information to haptically render graphical images for individuals who are blind or visually impaired. The device interacts directly with the computer screen, using the colors and patterns displayed by the image as a means to encode complex patterns of vibrotactile output, generating the texture feedback to render the image. In turn, the texture feedback was methodically designed to enable parallel processing of certain coarse information, speeding up the exploration of the diagram and improving user performance. The design choices were validated when individuals who are blind or visually impaired, using the multi-fingered display system, performed three-times better using textured image representations versus outline representations. Furthermore, in an open-ended object identification task, the display device saw on average two-times better performance accuracy than that previously observed for raised-line diagrams, the current standard for tactile diagrams.

The essay is about how people perceive repetition in games and how old visual rules can help designers make the right choice when they create modular objects. By understanding the relationships between contrast and affinity in the visual to create an interest for the player and understand that this exists in many areas of the visual rules such as geometric shapes, silhouettes and colors, etc. How people in the game industry approach creating modular objects while at the same time coping with the problem of obvious repetition which can make models seem boring and not visualy dynamic. And how the modular method can make it difficult to keep up the creativity when bound to certain parameters that modularity requires.

Thesis (M.Ed.)--University of Hong Kong, 1987. / Includes bibliographical references (leaf 183-209). Also available in print.

Purpose and hypothesis: The purpose of this study was to optimize and standardize the following parameters of sweep Visually Evoked Potential (sVEP) in adults: criteria for fitting the regression line to estimate threshold, luminance, electrode placement, temporal frequency, sweep direction, presence of fixation target and stimulus area. The hypothesis is that the parameters chosen will have an impact on the measured visual acuity, contrast threshold and on the number of viable sVEP plots. Methods: The Power Diva software, Version 1.9 was used for this study. Five gold cup active electrodes, one reference electrode and one ground electrode were used to measure the Electroencephalography (EEG) signals. Six adult participants (aged 17 to 35 years), with corrected to normal visual acuity and no history of ocular disease took part in each experiment, except for the repeatability experiment in which 3 subjects participated. Four criteria for regression line fitting were compared. Psychophysical thresholds were used to validate the sVEP measures for the different criterion and repeatability of sVEP was estimated for 10 sessions. The effect of luminance (25 cd/m2, 50 cd/m2, 100 cd/m2), electrode placement (Power Diva and ISCEV), temporal frequency (6 Hz, 7.5 Hz, 10 Hz), sweep direction, fixation target and stimulus area were investigated. A repeated measure ANOVA statistical method was used to analyze the average threshold and the number of viable plots out of five active channels for all subjects. Results: Criterion 2 and 3 gave better visual acuity, higher contrast sensitivity, better repeatability and gave results that were closer to the psychophysical threshold than criterion 0 and 1. Luminance of 25 cd/m2 gave significantly fewer viable readings than 50 and 100 cd/m2 while measuring visual acuity (F = 5.11, df = 2, p = 0.0295). Temporal frequency of 7.5 Hz gave significantly more viable readings than 6 and 10 Hz while measuring visual acuity (F = 50.53, df = 2, p < 0.0001) and contrast threshold (F = 9.87, df = 2,p = 0.0043). There was a highly significant interaction of criterion with temporal frequency (F = 1536.98, df = 6, p < 0.0001) while measuring contrast threshold. There was a significant interaction of criterion with sweep direction (F = 4.26, df = 3, p = 0.0231) and for the number of readings (F = 3.75, df = 3, p = 0.0343) while measuring visual acuity. There was an interaction of criterion with sweep direction (F = 4.97, df = 3, p = 0.0136) while measuring contrast threshold at a spatial frequency of 1 cpd. There was a significant effect of fixation target (F = 7.64, df = 1, p = 0.0396) while measuring visual acuity. There was a significant effect of stimulus area (F = 11.78, df = 4, p < 0.0001) on the number of readings while measuring contrast threshold. Conclusion: The sVEP parameters chosen do have a significant effect on visual acuity, contrast threshold and on the number of viable readings. The following parameters are recommended in adults on the basis of results; Criterion 2 or 3 for fitting regression line (C2 - regression line fitted from the signal peak amplitude to the last data point with a signal to noise ratio (SNR) >1; C3 – similar to criterion 2, but the threshold should be within sweep range used), luminance of 50 or 100 cd/m2 , either Power Diva (PD) or International Society for Clinical Electrophysiology of Vision (ISCEV) electrode placement, temporal frequency of 7.5 Hz, either sweep direction, measurement with the central fixation target, larger stimulus area.

Purpose and hypothesis: The purpose of this study was to optimize and standardize the following parameters of sweep Visually Evoked Potential (sVEP) in adults: criteria for fitting the regression line to estimate threshold, luminance, electrode placement, temporal frequency, sweep direction, presence of fixation target and stimulus area. The hypothesis is that the parameters chosen will have an impact on the measured visual acuity, contrast threshold and on the number of viable sVEP plots. Methods: The Power Diva software, Version 1.9 was used for this study. Five gold cup active electrodes, one reference electrode and one ground electrode were used to measure the Electroencephalography (EEG) signals. Six adult participants (aged 17 to 35 years), with corrected to normal visual acuity and no history of ocular disease took part in each experiment, except for the repeatability experiment in which 3 subjects participated. Four criteria for regression line fitting were compared. Psychophysical thresholds were used to validate the sVEP measures for the different criterion and repeatability of sVEP was estimated for 10 sessions. The effect of luminance (25 cd/m2, 50 cd/m2, 100 cd/m2), electrode placement (Power Diva and ISCEV), temporal frequency (6 Hz, 7.5 Hz, 10 Hz), sweep direction, fixation target and stimulus area were investigated. A repeated measure ANOVA statistical method was used to analyze the average threshold and the number of viable plots out of five active channels for all subjects. Results: Criterion 2 and 3 gave better visual acuity, higher contrast sensitivity, better repeatability and gave results that were closer to the psychophysical threshold than criterion 0 and 1. Luminance of 25 cd/m2 gave significantly fewer viable readings than 50 and 100 cd/m2 while measuring visual acuity (F = 5.11, df = 2, p = 0.0295). Temporal frequency of 7.5 Hz gave significantly more viable readings than 6 and 10 Hz while measuring visual acuity (F = 50.53, df = 2, p < 0.0001) and contrast threshold (F = 9.87, df = 2,p = 0.0043). There was a highly significant interaction of criterion with temporal frequency (F = 1536.98, df = 6, p < 0.0001) while measuring contrast threshold. There was a significant interaction of criterion with sweep direction (F = 4.26, df = 3, p = 0.0231) and for the number of readings (F = 3.75, df = 3, p = 0.0343) while measuring visual acuity. There was an interaction of criterion with sweep direction (F = 4.97, df = 3, p = 0.0136) while measuring contrast threshold at a spatial frequency of 1 cpd. There was a significant effect of fixation target (F = 7.64, df = 1, p = 0.0396) while measuring visual acuity. There was a significant effect of stimulus area (F = 11.78, df = 4, p < 0.0001) on the number of readings while measuring contrast threshold. Conclusion: The sVEP parameters chosen do have a significant effect on visual acuity, contrast threshold and on the number of viable readings. The following parameters are recommended in adults on the basis of results; Criterion 2 or 3 for fitting regression line (C2 - regression line fitted from the signal peak amplitude to the last data point with a signal to noise ratio (SNR) >1; C3 – similar to criterion 2, but the threshold should be within sweep range used), luminance of 50 or 100 cd/m2 , either Power Diva (PD) or International Society for Clinical Electrophysiology of Vision (ISCEV) electrode placement, temporal frequency of 7.5 Hz, either sweep direction, measurement with the central fixation target, larger stimulus area.

Researchers have learned much about how sighted individuals seek information on Web sites - for example, users follow "information scent" as they move from page to page, and individual differences may impact successful information seeking on the Web. While it is possible that individuals with disabilities, especially those with severe visual impairments, perform information-seeking activities in a similar manner, little is known about how individuals who use screen readers to navigate actually seek information on the Web. In this study, we used both qualitative and quantitative measures to investigate the Web navigation techniques of four screen-reader users and how a user’s experience affects these navigation techniques and his or her ability to successfully complete an information-finding task. We compared metrics for between-page and within-page navigation to studies of sighted users. We also considered how a Web site’s compliance with Section 508 guidelines affects the overall information-finding experience of a visually-impaired individual. We discovered that among the four individuals in this study, user experience was not necessarily indicative of a successful information-finding experience. As individuals, the participants' navigation techniques varied widely; as a group, they generally searched more frequently and used the back button less frequently than has been reported for sighted individuals. Screen-reader users in this study followed a more flimsy, linear navigation style and generally used scrolling actions rather than searching actions. When using a Web site that has a Section 508 compliant home page, we found that the screen-reader users in this study completed information-finding tasks significantly more quickly, used significantly fewer actions, and reported a more satisfying information-finding experience. They were also more successful at finding the information goal and encountered fewer impasses. Using both quantitative and qualitative measures was critical in this study. The quantitative metrics allowed us to compare values and the qualitative data provided additional insight into individual differences as well as allowing a deeper understanding of the quantitative data. The information from this study contributes to the growing body of research knowledge about screen-reader users. It also contributes a new understanding of screen-reader users that can be used by the worldwide community of Web developers, designers, and users. / text