A review of current knowledge on Electronic Vision Enhancement Systems for the visually impaired

Abstract

Magnification can be provided to assist those with visual impairment to make the best use of remaining vision. Electronic transverse magnification of an object was first conceived for use in low vision in the late 1950s, but has developed slowly and is not extensively prescribed because of its relatively high cost and lack of portability. Electronic devices providing transverse magnification have been termed closed-circuit televisions (CCTVs) because of the direct cable link between the camera imaging system and monitor viewing system, but this description generally refers to surveillance devices and does not indicate the provision of features such as magnification and contrast enhancement. Therefore, the term Electronic Vision Enhancement Systems (EVES) is proposed to better distinguish and describe such devices. This paper reviews current knowledge on EVES for the visually impaired in terms of: classification; hardware and software (development of technology, magnification and field-of-view, contrast and image enhancement); user aspects (users and usage, reading speed and duration, and training); and potential future development of EVES.Keywords: closed-circuit television, electronic vision enhancement system, low vision, visual impairment Electronic Vision Enhancement SystemsThis paper reviews current knowledge on Electronic Vision Enhancement Systems (EVES) for the visually impaired. The initial section classifies EVES in terms of their camera, display and power supply characteristics. The second section examines Ôhardware and softwareÕ issues in terms of the development of EVES technology over the past three decades, magnification and field-ofview, contrast and image enhancement. The subsequent section investigates research conducted into ÔuserÕ aspects of EVES in the form of users and usage, reading speed and duration, and training. Finally, the last section discusses potential future development of EVES. EVES classificationThe broad range of EVES currently on the market has resulted from general consumer demand for the individual components (video cameras and display screens) and the simplicity of connecting them together. As a result, many of the companies selling EVES do not have a strong interest or background in low vision rehabilitation. Although attempts have been made to classify EVES in terms of performance attributes, such as portability, ease of operation and aesthetic appearance (Strong and Byard, 1992), these are difficult to quantify objectively. Uslan et al. (1996) described a classification for EVES available at that time in the USA, in the form of two main types: those in which the camera and/or display are mounted on a stand and those that use a handheld camera. The stand-mounted systems were further subdivided into Ôin-lineÕ or Ôside-by-sideÕ configurations and the features of representative systems were listed (such as the provision of colour and magnification range). A similar classification of handheld systems was recorded, with system configuration divided into

Reading comparative study: Electronic vs. conventional devices

“…Electronic devices offer some advantages as bigger working distance, higher magnification than conventional devices [5,6]. Nevertheless, more training sessions are required in order to improve the use of these kind of devices.…”

Reading e-books on a near-to-eye display: Comparison between a small-sized multimedia display and a hard copy

“…Although NEDs have been used as electronic vision enhancement displays for the visually impaired, the number of studies on the use of NEDs for reading tasks or as accessories for enhancement for small-sized displays is limited [62,63,55,36]. Sheedy and Bergstom [55] found a small increase in task performance speed when tasks were performed on near-eye displays compared to flat panel displays and hard copies.…”

Evaluation of a gaze-controlled vision enhancement system for reading in visually impaired people

“…Electronic Vision Enhancement Systems (EVES) have a great potential to improve perceptual performance of low vision patients [19,20]: in addition to magnification, they can provide many kinds of visual enhancements [21]. A recent survey indicated that most low vision patients express an interest in image processing technology that could be implemented for television viewing and for computer use [22].…”