First off; This is totally a bookmark for myself. But I’d be amazed if it actually helps you, the reader!
I started using a static self-hosted NanoGallery2 for holiday photos, and the thumbnails look better when they are all the same width.
Execute this in the directory where your JPGs reside, all thumbnails have “thumb-” prefixed to their bigger picture counterpart.
❯ for i in *.JPG; do convert -auto-orient -thumbnail '200x>' $i thumb-$i; done;