Understanding IIIF image usage based on server log analysis

Abstract

Numerous libraries and museums have adopted the International Image Interoperability Framework (IIIF) that promotes mutual use of images among different institutions. In a IIIF-compatible digital collection, images are retrieved via IIIF Image API (Application Programming Interface), wherein regions of images can be specified. Thus, it is possible to investigate image usage in detail by examining the image regions that have been requested. In this article, we propose a log analysis method to measure the image usage and to visualize the analysis outcomes. Specifically, we employ the number of accesses to each pixel and visualize the results using heat maps. Given that a pixel is the smallest image unit, we apply herein a fine-grained analysis. The analysis method can be used in different applications including research tools in which researchers examine images and heat maps that show which regions of the images have already been examined by collaborators.