Putting this here because I didn’t see it mentioned elsewhere and it might be useful for others. Thinking about the history of the Islandora solution packs for different media types, the Basic Image Solution Pack was probably the first one written. Displaying a JPEG image, after all, is — well — pretty basic. I’m working on an Islandora project where I wanted to add a viewer to Basic Image objects, but I found that the solution pack code didn’t use them. Fortunately, Drupal has some nice ways for me to intercede to add that capability!