This content is quite old. You might want to check out this modern way of visual diffing, using Puppeteer instead
Watches you browse, takes screenshots, tells you when they change.
First you record a basic flow and take screenshots in between. Afterwards, when you’ve done some changes, you can let the flow play back again, and Huxley will re-take screenshots to compare with the ones from the first run. Video above shows how it works. By Facebook.
Related: Wraith, a likewise tool by the BBC.