Thanks for your help this past week. I'll be sure to mention you in my blog post. Unfortunately, I tend to burn out hard if I focus for too long on a single task, and I feel myself approaching that again. I'll try to be back in a couple days to a week. I feel tantalizingly close to getting this project actually underway, and I've been on it for a week most months for a year.
Until then, the other end is shaping up like so:
I did my first test of regular SANE and got the usual errors that get in the way of plug and play scanning. I need to adjust permissions in places I forget where.
XSANE does not appear to be in the repository. If someone's willing to compile it, might as well aim for aarch64, as I'm itching to learn that when I get a spare SD card -- I used my last one for this project as it is.
Note: I was warned that XSANE may only support 24 bit color depth, and I'm looking to work in the scanners' native 48.