Sensory aids for the blind: A challenging problem with lessons for the future

The two major objectives of sensory aids for the blind are to permit access to printed matter and to permit safe travel through the environment. The difficulties of designing technological means to achieve these objectives are in many respects unrelated to the concerns of the engineering laboratory. Social, economic, political, and logistic considerations all play a role. The "blind population" in the United States includes both the totally blind and those with a wide range of visual impairment. This population totals about 400 000 people in which the aged, the multiply handicapped, and those with significant residual vision predominate. Singly handicapped, working-aged people are the initial targets of the current sensory aids. Expansion of their range of usefulness to larger fractions of the blind population is expected to come later. About 800 agencies serve the blind population in the United States, and in 1967 they were responsible for an annual expenditure of 1 million. Nevertheless, several potentially useful prototype devices have been developed and are about to be evaluated in this country; at least one is of foreign origin. But if these devices are ever to have the opportunity of reaching the blind public, then mechanisms for evaluation, field trials, manufacture, and deployment must be set up. The field of currently active sensory-aids research programs is reviewed. Several programs are concerned with increasing the convenience and accessibility of braille by the application of computer technology. Nevertheless, despite the unquestionable value of these developments, the usefulness of braille is limited by its bulk, its cost, and the transcription time. To provide direct access to printed documents several devices are being developed that transform optical images from a printed page into auditory or tactile displays requiring motivation and training for effective use. These machines are termed "direct-translation" units and are designed for simplicity and low cost. Other systems utilize print recognition techniques to create a reading machine providing braille or speech as an output. These machines offer potentially faster reading rates and their use promises to be easier to learn than direct-translation machines, but at the penalty of complexity and high cost. Several mobility aids designed to augment the cane or guide dog have recently been developed. These are also described. The prospects of achieving direct input to the visual cortex are discussed. It is apparent that the cost of this research is likely to be extremely high in relation to the size of the blind population which might ultimately benefit. Somewhat more easily realizable is a visual substitution system involving stimulation of an area of the skin. Several systems are being developed but all suffer from limitations in image resolution. Finally, an examination of the organization of research and funding reveals that the U.S. program is small, poorly coordinated, and contains some seemingly unnecessary duplication of effort. Several obvious lessons emerge which, if heeded, could greatly improve the effectiveness of sensory-aids research by providing development, manufacture, evaluation, and deployment services within an integrated program

Investigating Potential Combinations of Visual Features towards Improvement of Full-Reference and No-Reference Image Quality Assessment

Objective assessment of image quality is the process of automatic assignment of a scalar score to an image such that the rating or score corresponds to the score provided by the Human Visual System (HVS). Despite extensive studies since the last two decades, it remains a challenging problem in image processing due to the presence of different types of distortions and limited knowledge of the HVS. Existing approaches for assessing the perceptual quality of images have relied on a number of methodologies that directly apply known properties of the HVS, construct hypotheses considering the HVS as a blackbox and use hybrid approaches that apply both of the techniques. All of these methodologies have relied on different types of visual features for Image Quality Assessment (IQA). In this dissertation, we have studied the problem of different types of IQA from the feature extraction point of view and showed that effective combinations of simple visual features can be used to develop IQA approaches having competitive performance with the state-of-the-art. Our work is divided into four parts each having the final goal to bring about performance improvement in the areas of Full-Reference (FR) and No-Reference (NR)-IQA. We have gradually moved from FR to NR-IQA in the works presented in this dissertation. First, we propose improvements in two existing FR-IQA techniques by introducing changes in the features used. Next, we propose a new FR-IQA technique by extracting image saliency as global features and combining them with the local features of gradient and variance to improve the performance. For NR-IQA, we propose a novel technique for sharpness detection in natural images using simple features. The performance of this method provides improvement over the existing methods. After working with the specific purpose NR-IQA, we propose a general purpose technique using suitable features such that no training with pristine or distorted images or subjective quality scores is required. This technique, despite having no reliance on training, provides competitive performance with the state-of-the-art techniques. The main contribution of the dissertation lies in identification and analysis of effective features and their combinations for improving three different sub-areas of IQA

Estimation of signal distortion using effective sampling density for light field-based free viewpoint video

In a light field-based free viewpoint video (LF-based FVV) system, effective sampling density (ESD) is defined as the number of rays per unit area of the scene that has been acquired and is selected in the rendering process for reconstructing an unknown ray. This paper extends the concept of ESD and shows that ESD is a tractable metric that quantifies the joint impact of the imperfections of LF acquisition and rendering. By deriving and analyzing ESD for the commonly used LF acquisition and rendering methods, it is shown that ESD is an effective indicator determined by system parameters and can be used to directly estimate output video distortion without access to the ground truth. This claim is verified by extensive numerical simulations and comparison to PSNR. Furthermore, an empirical relationship between the output distortion (in PSNR) and the calculated ESD is established to allow direct assessment of the overall video distortion without an actual implementation of the system. A small scale subjective user study is also conducted which indicates a correlation of 0.91 between ESD and perceived quality

Ability of head-mounted display technology to improve mobility in people with low vision: a systematic review

Purpose: The purpose of this study was to undertake a systematic literature review on how vision enhancements, implemented using head-mounted displays (HMDs), can improve mobility, orientation, and associated aspects of visual function in people with low vision. Methods: The databases Medline, Chinl, Scopus, and Web of Science were searched for potentially relevant studies. Publications from all years until November 2018 were identified based on predefined inclusion and exclusion criteria. The data were tabulated and synthesized to produce a systematic review. Results: The search identified 28 relevant papers describing the performance of vision enhancement techniques on mobility and associated visual tasks. Simplifying visual scenes improved obstacle detection and object recognition but decreased walking speed. Minification techniques increased the size of the visual field by 3 to 5 times and improved visual search performance. However, the impact of minification on mobility has not been studied extensively. Clinical trials with commercially available devices recorded poor results relative to conventional aids. Conclusions: The effects of current vision enhancements using HMDs are mixed. They appear to reduce mobility efficiency but improved obstacle detection and object recognition. The review highlights the lack of controlled studies with robust study designs. To support the evidence base, well-designed trials with larger sample sizes that represent different types of impairments and real-life scenarios are required. Future work should focus on identifying the needs of people with different types of vision impairment and providing targeted enhancements. Translational Relevance: This literature review examines the evidence regarding the ability of HMD technology to improve mobility in people with sight loss

An exploratory scale of Christian privilege: The development of a scale to measure the attitudinal constituents of Christian privilege

Research surrounding measures of privilege awareness commonly involve White privilege awareness. However, relatively few (i.e., Privilege and Oppression Inventory) look other forms of privilege (i.e., heterosexual, sexism, religion). As such, this study looked to create a more extensive scale that would assess Christian privilege awareness among Christian participants. Items were adapted from theoretically analogous White privilege scales in addition to literature on Christian privilege. Using a sample of 391 participants recruited from Facebook, Reddit, SONA and Twitter, an exploratory factor analysis was run on a 28-item scale. The analysis suggested that a final 21-item, two-factor solution was the best fit for the data after considering factor cross loadings and variance explained. Convergent and concurrent validity are also established. Finally, future directions and limitations are also discussed

Review of substitutive assistive tools and technologies for people with visual impairments: recent advancements and prospects

YesThe development of many tools and technologies for people with visual impairment has become a major priority in the field of assistive technology research. However, many of these technology advancements have limitations in terms of the human aspects of the user experience (e.g., usability, learnability, and time to user adaptation) as well as difficulties in translating research prototypes into production. Also, there was no clear distinction between the assistive aids of adults and children, as well as between “partial impairment” and “total blindness”. As a result of these limitations, the produced aids have not gained much popularity and the intended users are still hesitant to utilise them. This paper presents a comprehensive review of substitutive interventions that aid in adapting to vision loss, centred on laboratory research studies to assess user-system interaction and system validation. Depending on the primary cueing feedback signal offered to the user, these technology aids are categorized as visual, haptics, or auditory-based aids. The context of use, cueing feedback signals, and participation of visually impaired people in the evaluation are all considered while discussing these aids. Based on the findings, a set of recommendations is suggested to assist the scientific community in addressing persisting challenges and restrictions faced by both the totally blind and partially sighted people