We are studying a large collection of digital images having 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 utilizes a small copy of each image (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 instantaneously access any individual full-size image in the collection as a video image. We regard our software as the beginning of the development of exploratory tools for studying collections of images as we routinely study batches of numbers. Our focus to date has been on developing a tool that will assist in selecting individual images for inspection. We anticipate that in the future we may wish to consider summary information and distributional properties of various aspects of the images. The talk included a videotape of our system in use.