Media accessibility for low-vision users in the MPEG-21 multimedia framework

Ethical and legal requirements have made accessibility a crucial feature in any information systems. This paper presents a content adaptation framework, based on the MPEG-21 standard, to help lowvision users have better accessibility to visual contents. We first present an overview of MPEG-21 Digital Item Adaptation (DIA) and the low-vision description toot which enables interoperable content adaptation. This description tool lists seven low-vision symptoms, namely loss of fine detail, lack of contrast, central vision loss, peripheral vision loss, hemianopia, light sensitivity, and need of light. Then we propose a systematic contrast-enhancement method to improve the content visibility for low-vision users, focusing on the first two symptoms. The effectiveness of the low-vision description tool and our adaptation framework is verified by some experiments with an adaptation test-bed. The major advantages of the proposed approach include 1) support of a wide range of low-vision conditions, and 2) customized content adaptation to specific characteristics of each user.