In order to obtain a variety of descriptions, each image is described three times before it is retired. Once an image is retired, the submitted descriptions are evaluated by library research staff who select the best description for each image. The selected descriptions are then converted to alt-text that can be accessed by assistive devices.
Below we have created a visual example of what alternative text looks like using Jean-Baptiste Greuze's The Wool Winder.
<img alt="Woman in a blue striped dress and bonnet winding balls of wool yarn alongside a cat.">
The alt-text description will be read aloud to the user by with an assistive device or assistive technology such as screen reader software.