Usage patterns of a Web-based image collection

This paper presents a study of user access patterns to a large, Web-based, image collection. The images are the entire collection of the Fine Arts Museums of San Francisco, the largest on-line collection of high resolution art images in the world. The images are served using a tile-based solution that allows a user to zoom-in and navigate within an image. We studied five months of web log data for this collection. Our analysis revealed the following: less than 10% of all available documents on the site were accessed in the five month period and document popularity appears to follow a Zipf distribution. Also, images have interesting areas which are viewed more than others, some image resolutions are viewed far more than others, and user navigation patterns vary between resolutions and are sensitive to download time. The paper discusses these results and their implications for the design of caches and archival storage systems to support this type of workload.