"The unfortunate state right now is that there are still millions and millions of unlabeled images across the web," said Laura Allen, a senior program manager on the Chrome accessibility team. She understands the issue as she has low vision herself. "When you're navigating with a screen reader or a Braille display, when you get to one of those images, you'll actually just basically hear 'image' or 'unlabeled graphic,' or my favorite, a super long string of numbers which is the file name, which is just totally irrelevant."
An example of a descriptive text given by the feature would be "Appears to be fruits and vegetables at the market" for an image of a market stall. The descriptions are couched with "appears to be" so users know they are generated by a computer and may not be fully accurate.
The feature is available only for users with screen readers that output spoken feedback or Braille. The images descriptions will be read by the screen reader, but will not appear visually on the screen.
To enable image descriptions on Chrome, go to Settings, then to Advanced at the bottom of the settings page. Find the "Accessibility" section and enable "Get image descriptions from Google." The feature can also be enabled for single web pages by right clicking to bring up the context menu and selecting "Get Image Descriptions from Google."