Twitter A11y: A Browser Extension to Make Twitter Images Accessible

Abstract

Twitter is integral to many people's lives for news, entertainment, and communication. While people increasingly post images to Twitter, a large majority of images remain inaccessible to people with vision impairments due to a lack of image descriptions (i.e. alternative text). We present Twitter A11y (pronounced ally), a browser extension to make images accessible through a set of strategies tailored to the platform. For example, screenshots of text that exceed the Twitter character limit are common, so we detect textual images, and automatically add alternative text using optical character recognition. Tweet images apart from screenshots and link previews receive descriptions from crowd workers. Based on an evaluation of the timelines of 50 self-identified blind Twitter users, Twitter A11y increases automatic alt text coverage from 2.6% to 25.6%, before crowdsourcing the remaining images.