Development and Evaluation of Vision Multiplexing Devices for Vision Impairments

Abstract

We have proposed a novel concept of vision multiplexing for the visually impaired -superimposing contour images over their natural view of a scene or over original images presented on a TV screen. We have implemented the concept using an optical see-through head mounted display to provide either visual field expansion to patients with peripheral field loss or vision enhancement to patients with central vision loss. We have also implemented the concept in a video player with dynamic magnification for patients with central vision loss. Results of initial testing in the lab and on the street are promising. KeywordsHead mounted display; multiplexing; vision impairment BackgroundWith normal vision we enjoy the benefits of a wide field of view, primarily used for navigation, orientation, and obstacle avoidance, together with high-resolution capabilities that enable discrimination of fine details. Visual impairments due to disease or injury usually affect only one of these aspects, either restricting the wide peripheral visual field (VF) in conditions such as retinitis pigmentosa (RP) and glaucoma, or damaging the high-resolution fovea in conditions such as age-related macular degeneration (AMD).When peripheral VF loss is severe (leaving useful VFs of less than 20° in diameter -tunnel vision), a patient's mobility can be affected due to reduced ability to spot obstacles and difficulties in navigation. When patients experience central vision loss, the ability to discriminate fine detail is affected due to an increase in contrast threshold for high-frequency patterns, which causes difficulties with reading regular-sized print and recognizing faces and watching TV.Traditional optical devices for the visually impaired restore, at least partially, the lost visual ability, but at a high cost for the remaining functionality. For example, magnification improves NIH Public Access Author ManuscriptInt J Artif Intell Tools. Author manuscript; available in PMC 2010 June 1. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript resolution but inherently limits the field of view. Similarly, minifying devices increase the field of view, but cause a loss of resolution in addition to spatial distortions, and restriction of freescanning eye movements. Our novel design approach, called "vision multiplexing", attempts to avoid or reduce these limitations by combining both the wide field-of-view and the highresolution capabilities in devices in ways that permit these functionalities to be both separable and useful 1 . Augmented vision systems lend themselves to vision multiplexing. In this paper we report on the development and preliminary evaluations of two augmented vision systems that implement spatial multiplexing via superposition 1 (See Fig. 1).The first system incorporates a head-mounted display (HMD) and has applications for patients either with tunnel vision or central vision loss. Contour images derived from a miniature video camera are presented in an optical see-through HMD. For patients with tunnel ...

A reconfigurable real-time morphological system for augmented vision

“…While current trends in augmented vision for the visually impaired have extensively utilised binary-based edge overlaying systems, e.g. Sobel edge detection, with a rigid and fixed implementation [7][8][9][10][13][14][15][18][19][20], the proposed method is highly flexible, offering a high degree of real-time user customisation, where the user can switch between various morphology edge gradient techniques of selectable magnitude and edge thickness. The proposed grayscale morphological architecture exploits duality, capable of producing erosion and dilation functions from the same morphological operation architecture.…”

“…Currently, the most notable contributions in augmented vision for the visually impaired and development of visual enhancement embedded devices are reported by Peli et al [8][9][10][11][12][13] and Atabany et al [14,15]. However, the work presented on embedded devices are severely limited in hardware technical details while opting to focus more on psychophysical testing of fixed visual enhancement algorithms.…”

“…This has led to edge detection, a common digital image processing technique, being a critical underlying process in high spatial frequency enhancement. Peli et al originally proposed augmented vision models utilising visual multiplexing techniques such as the wideband enhancement algorithm that superimposed modified image edges over the original image, enhancing the high spatial frequency components [8,9]. Further work includes modifying the discrete cosine transform to increase the mid-range spatial frequencies of JPEG images [10], which was then extended to include MPEG video enhancement [11] and recently a modified edge detection algorithm for contour shape enhancement applied to image luminance channels [12].…”

Mediated-reality magnification for macular degeneration rehabilitation

“…As the percentage of the population being older than 50 continues to grow, AMD is becoming a major public health problem worldwide, where its damage cannot be reversed. Nevertheless, enhancement of different low vision conditions by means of adaptive technology and modern techniques is conceivable [7][8][9][10].…”

Performance of visual search tasks from various types of contour information

“…This research deals with the performance when employing image boundary features (different contour types) for image understanding (such as object detection and identification). The research is associated with a new visual aid [1][2][3] for patients with a severely restricted visual field of view (FOV), commonly termed "tunnel vision." This aid combines a seethrough head-mounted display (HMD) and a simultaneous minified contour view of the wide-field image of the environment.…”