How I Did the Animorphs Covers
Here's a post by David Mattingly, the guy who did all those Animorphs book covers, on how he did all those Animorphs book covers. It was all done in software with photos, but he sketched out all the concepts first by hand to get approval from the publisher, so there are some of those sketches in the post and that's cool.
For morphing he used a program called Elastic Reality which I'd never heard of before but which was apparently the industry standard for this kind of thing










