Here is a story of how an "index of photo" can bring a forgotten history to life: The Story: The Archivist's Choice
A photo index does the same for your digital library. Instead of relying on memory to find a file, you use (data about data) to tag, rate, and organize your images so they are searchable. index of photo
If you mean an "index" as in a directory of multiple posts represented by photos: Layout Style : Choose between a (thumbnails with titles) or a list with images on the side. Query Loops Here is a story of how an "index