An interactive icon index: images of the outer planets

We are interested in the exploratory analysis of large collections of complex objects. As an example, we are studying a large collection of digital images that has nearly 30,000 members. We regard each image in the collection as an individual observation. To facilitate our study we construct an index of the images in the collection. The index uses a small copy of each image (an icon or a .thumbnail.) to represent the full-size version. A large number of these thumbnails are laid out in a workstation window. We can interactively arrange and rearrange the thumbnails within the window. For example, we can sort the thumbnails by the values of a function computed from them or by the values of data associated with each of them. By the use of specialized equipment (a single-frame video disk recorder/player), we can instantly access any individual full-size image in the collection as a video image. We regard our software as an early development of statistical exploratory tools for studying collections of images and other complex objects in the same way we routinely study batches of numbers. We expect that the concept of a visual index will extend to other collections of complex objects besides images, for example, time series, functions, and text.