Images on the Web present a major accessibility issue for the visually impaired, mainly because the majority of them do not have proper captions. This paper addresses the problem of attaching proper explanatory text descriptions to arbitrary images on the Web. To this end, we introduce Phetch, an enjoyable computer game that collectsexplanatory descriptions of images. People play the game because it is fun, and as a side effect of game play wecollect valuable information. Given any image from the World Wide Web, Phetch can output a correct annotationfor it. The collected data can be applied towards significantly improving Web accessibility.

The Web is not built for the blind. Only a small fraction of major corporate websites are fully accessible to the disabled, let alone those of smaller organizations or individuals . However, millions of blind people surf the Web every day, and Internet use by those with disabilities grows at twice the rate of the non-disabled . One of the major accessibility problems is the lack of descriptive captions for images. Visually impaired individuals commonly surf the Web using “screen readers,” programs that convert the text of a webpage into synthesized speech. Although screen readers are helpful, they cannot determine the contents of images on the Web that do not have descriptive captions.