I use digiKam (currently version 4.10.0) to manage my photos, and would like to add face tags to images. For images with no tags yet, no problem: I can tag the faces when I tag the images. For images that the face-detection algorithm succeeds on, also no problem: just use the tags from the algorithm. But if the algorithm doesn't find a face and I've already tagged the image (with a regular tag), there's no commonality between the images I want but the absence of a face tag. There's no readily apparent way to search for images that have regular tags but don't have face tags. Does anyone know of a way to do this?
Ideally, I'd like to be able to include tag content in the search. E.g., if an image has regular tags for Alice and Bob but a face tag only for Alice, I'd like it to show up so I can tag Bob. But even being able to find an image with a regular tag for Alice and no face tags at all would be helpful.
EDIT: I think that what I essentially need is a way to search specifically for tagged faces in Advanced Search box; it would then be easy enough to reverse the search by picking images that don't meet the criterion/a.