International Journal on Artificial Intelligence Tools

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.

We describe a wayfinding system for blind and visually impaired persons that uses a camera phone to determine the user's location with respect to color markers, posted at locations of interest (such as offices), which are automatically detected by the phone. The color marker signs are specially designed to be detected in real time in cluttered environments using computer vision software running on the phone; a novel segmentation algorithm quickly locates the borders of the color marker in each image, which allows the system to calculate how far the marker is from the phone. We present a model of how the user's scanning strategy (i.e. how he/she pans the phone left and right to find color markers) affects the system's ability to detect color markers given the limitations imposed by motion blur, which is always a possibility whenever a camera is in motion. Finally, we describe experiments with our system tested by blind and visually impaired volunteers, demonstrating their ability to reliably use the system to find locations designated by color markers in a variety of indoor and outdoor environments, and elucidating which search strategies were most effective for users.

While Eye Gaze Tracking (EGT) systems have demonstrated their potential as computer cursor control devices, their application outside the laboratory environment has been less prominent than originally expected. This may be due to limitations in the stability of the cursor controlled by EGT devices and in the potential for unintended selections ("clicks"). To address these EGT limitations, we have developed a cursor control system that integrates electromyogram-based control with EGT-based control. This integrated system allows a user to perform small cursor displacements and selection operations ("left click") by detecting distinct changes in electromyogram (EMG) signals generated during specific facial movements. Specifically, the system monitors and processes, in real time, EMG signals from four electrodes attached to the head of the subject. We compared the performance of this EMG/EGT integrated system, with the performance of a stand-alone EGT system and a hand-held mouse, in point-and-click trials. Statistical analysis of the results indicates that the EMG/EGT system is slower than the EGT system and the mouse, but it also revealed that it is significantly less error-prone than the EGT-only system. The analysis also revealed that the performance of the EMG/EGT system does not seem to be well matched to Fitts' model.

With the aging of the population, the prevalence of eye diseases and thus of vision impairment is increasing. The TV watching habits of people with vision impairments are comparable to normally sighted people,¹ however their vision loss prevents them from fully benefiting from this medium. For over 20 years we have been developing video image-enhancement techniques designed to assist people with visual impairments, particularly those due to central retinal vision loss. A major difficulty in this endeavor is the lack of evaluation techniques to assess and compare the effectiveness of various enhancement methods. This paper reviews our approaches to image enhancement and the results we have obtained, with special emphasis on the difficulties encountered in the evaluation of the benefits of enhancement and the solutions we have developed to date.

This paper deals with various ways of controlling an electrically powered wheelchair beyond the usual method involving a manual joystick. The main focus is on the newest version of HaWCoS – the "HAnds-free Wheelchair COntrol System" – allowing persons with severe disabilities to reliably navigate a power wheelchair without the need to use the hands. All the user has to do is to produce a sequence of tiny contractions of an arbitrary muscle, e.g., by raising the eyebrow. The working prototype of the system, which has been realized as a stand-alone device, is introduced in detail, together with a closer look at the muscle-based control principle and a brief description of a PC-based simulator. The advantages and the drawbacks of the system are discussed on the basis of a rather simple real-life experiment. The paper also elaborates on possible approaches to improve HaWCoS (by reducing or eliminating its problems) in the future. In addition to a quick software solution and a controller implementation involving supplemental sensory information, planned "improvements" include the development of an "intelligent wheelchair" with HaWCoS being some sort of a prototype for the User Interface component.

While reading devices for the visually impaired have been available for many years, they are often expensive and difficult to use. The image processing required to enable the reading task is a composition of several important sub-tasks, such as image capture, image stabilization, image enhancement and page-curl dewarping region segmentation, regions grouping, and word recognition In this paper we deal with some of these sub-tasks in an effort to prototype a device (Tyflos-reader) that will read a document for a person with a visual impairment and respond to voice commands for control. Initial experimental results on a set of textbook and newspaper pages are also presented.