Abstract
We contribute a method that lets people create a visual history of custom notifications to track personally meaningful changes to web pages. Notifications are assembled as a collage of regions extracted from the fully rendered (bitmap) representation of the web pages. They are triggered when visual changes between successive visits are detected within regions. To use the system, a person specifies a notification by clipping personally interesting regions from the bitmap representation of a web page and reformatting them into a small collage. The person then specifies regions on the page that will be monitored and compared for visual differences over time. Based on this specification, the system periodically revisits the page in the background on behalf of the user and automatically generations a notification (the collage plus a title and timestamp) when differences are detected. Finally, the person views the generated notifications in several ways: as only the most recently changed version (to illustrate current state), or as an image history that can be individually browsed or played back as a continuous video stream.
