I'm annotating anatomical drawings for students - rather than having a huge clutter of annotations around the drawing I want to be able to set things up so that annotations, and possibly even another image, are revealed when the student either rolls over a certain portion of the image or clicks on it. Ideally I would also be able to combine the click with show/hiding another image layer to highlight certain other features graphically. I know that Preview has basic annotation tools but I need something a bit more sophisticated. This is going to be an important and long term project so I don't mind investing in and learning a "pro" app if that's what it takes. Lastly, assuming that I can do the above in a particular app (someone here will tell me about!) how would I then go about making the resulting interactive image accessible to students without the app? After all if I can't do that then there's not much point . . . thanks in advance!