I've updated the branch for this PR to use main, which provides libvips 8.12.0-rc1.

Please can you update the code to take an approach similar to #2934 (comment)

Thanks, I've updated the code with the Is16Bit function. The test still complains though with:

(process:38668): GLib-GObject-WARNING **: 17:16:45.992: value "16" of type 'gint' is invalid or out of range for property 'bitdepth' of type 'gint'

but I may have missed something when I compiled the library.

Thanks for the updates, please can you rebase your branch against the upstream main rather than master.

Ok, I think I rebased it although I have to admit I have absolutely no idea if everything turned out fine.... at one time I think I did an empty commit and then stuff seemed to work but if it doesn't perhaps it's easier add the fixes manually.

Thank you, landed via 2deced0