Interesting thought by Mike Shatzkin on the unlikeliness of pictures in eBooks anytime soon (bold added):
The proliferation of formats, devices, screen sizes, and delivery channels means that the idea of “output one epub file and let the intermediaries take it from there” is an unworkable strategy. [Here's one reason why:] … Epub can “reflow” text, making adjustments for screen size. But there is no way to do for that for illustrations or many charts or graphs without human intervention (for a long while, at least.) Even if you could program so that art would automatically resize for the screen size, you wouldn’t know whether the art would look any good or be legible in the different size. A human would have to look and be sure.
Mike is talking here about the issue I wrote about in the foundational article for Seeing the Picture — Pictures are in many ways an intractable problem for automation — In many situations, the best use of pictures requires intelligent human input.