The scanning tools in the hplip package need "python3-scikit-image" for full functionality. That dependency is currently missing, and I'm considering adding it. I can't test this well myself because I'm missing suitable hardware. But the way hplip typically deals with missing dependencies at runtime, users will at best see a generic or misleading error message; more likely, some options will simply be missing or greyed out for no obvious reason. My problem is that "python3-scikit-image" pulls in a whole bunch of additional python packages (155 packages / 576 MiB on my TW system, which already had quite a bit of python stuff installed). Installing it with --no-recommends pulls in "only" 8 packages / 156 MiB. I'm now wondering if I should add this requirement to hplip as "Requires" or "Recommends". I wouldn't normally classify it as a hard requirement, as it's only needed for special functionality provided only with special HP ScanJet models (e.g. "punchhole removal"). From that point of view, it's clearly a "recommends" or even a "suggests". However, if I use "recommends", people using "--no-recommends" won't get the scikit stuff at all and miss functionality in obscure ways, whereas people using "--recommends" would get the full 155 recommended packages. If I use "Requires", OTOH, the result with "--recommends" would be the same, but with "--no-recommends", users would "only" need to install the 8 packages that python3-scikit-image pulls in hard, and most likely the required run-time functionality would be available to them. The latter would be my personal preference as a user (well - for my printer model the extra functionality isn't offered anyway, so for me personally, using "suggests" is actually the best). Another option would be to separate out these new scanning tools "hp- scan" and "hp-uiscan" into an extra package and add the requirements there. I don't think they have many users yet, as I expect most users to simply use the usual SANE tools, xsane and scanimage. But that's just a guess. But if I do this, I have the same problem, because "hplip" would need to have a "Recommends: hplip-hpscan". Hints and opinions welcome. Martin