This fan documentary premiered yesterday, and features excellent new audio interviews with Ron, Dave and Mark Ferrari. Orson Scott Card and Steve Purcell have also contributed, voiced by actors. It touches on most aspects of the production, including plenty of details that were new to me and some fun anecdotes.
On another note, I'd like to show some comparisons of what I mean by updating existing posters. The improvements in quality result from a combination of a) having access to better sources and b) having better tools at my disposal. Note that on my old versions I often used fake texture and bump-mapping to simulate brush strokes and detail where originally there was nothing like that (although some details and grain are added artificially in the new versions as well). Here are a few samples:
https://imgur.com/hcrfIOu
I'd also like to show an extreme example of better ways to upscale images using basically artificial intelligence (or "machine learning"). The promotional "Infernal Machine" artwork (or something that was an early concept for the main cover) was originally only shared on Drew Struzans own website, albeit at very low resolution. Here's how it looks after upscaling it in various steps: