An image data storage system and associated method store, on one or more disk drives in a disk drive array, original image data for different images as well as multiple resolution levels of compressed image data for each image. The lowest resolution level image data for multiple different images (i.e., “thumbnail” copies of images) are grouped together and stored within sectors closest to the center. The progressively higher resolution levels of image data for the same images can similarly be grouped together and stored within sectors sequentially from a first track closest to the center to a last track closet to an outer edge. Alternatively, all higher resolution levels of image data for any single image can be grouped together and stored within a same sector as close to the center as possible. This organization can significantly reduce average access time for large collections of images.