At the time of the Sydney 2000 Olympics, access to the Internet was becoming more common outside of academic settings, and many people used the official event website to keep track of the news.
One such user, Bruce Lindsay Maguire, won a court case against the organising committee because that website wasn’t accessible to him. One point of complaint was that no alt-text had been provided for images, so his Braille display wasn’t able to tell him what the images represented. The Australian Human Rights Commission website features a summary of the case.
With 22 years now passed, it’s easy to imagine this problem was confined to the early and more experimental years of the Web, but that’s not always the case.
Let’s use Instagram as an example, which employs software to try to identify what’s in a picture. A typical caption is ‘May be a picture of two people’ or ‘May be cars on a road’. However, it’s not easy to find the option to type your own alt-text. On the Android app, you need to click a small ‘Advanced settings’ link just before posting the picture, then head to ‘Write alt text’. There seems to be no good reason not to provide this box in plain sight.
A good piece of alt-text is one that fills in any important details that aren’t conveyed by the image caption or any other context. It doesn’t need to contain every detail, just enough to help someone understand the scene if they can’t see it.
One exception is purely decorative images. On this page, I often use headers created from fractals; these are generated by software as a copyright-free source of images. It’s not important to know that the image has dots and swirls of blue or pink, so these are typically labelled as simply ‘Fractal’.