Photos of the actual user would, of course, be subject to all the other GDPR requirements around that user's data, but random other people that happen to be in those photos should have no impact on the GDPR scope unless you're attempting to identify them. From [1] on consent:

"Recital 51 notes that photographs will qualify as biometric data only when they are processed “through a specific technical means allowing the unique identification or authentication of a natural person.”"

So Facebook trying to match your face to tag you in a photo counts, but the usage in this weather app doesn't appear to.

[1]: https://iapp.org/news/a/top-10-operational-impacts-of-the-gd...

How about if you are just identifying that whether its a Male or Female and their ages without uniquely identifying that it was 'John Doe'.. Does GDPR will still have problems with that ?

I don't believe that would fall afoul under this particular section, but I know there are specific sections that deal with anything regarding gender, ethnicity, sexual preference, religious affiliation, etc. that you might have to worry about. I'm pretty sure you could still do it without any kind of consent (which is what the case here was related to), but the gender data you collect from it might have restrictions on use or other caveats you'd have to deal with.

Honestly I'd have to do some specific research and then probably contact a lawyer to have them do some research just to CYA (or rather, mine).

Well, all pictures require moderation before users see them. I'm investigating using one of the cloud offerings from MS or IBM that does bad-photo-detection so I can offload much of that responsibility before I have to see any photos on the backend myself.

For the humans in pictures, definitely don't want that and would reject the photos. I'd rather reject many photos that contain the sky and have issues than accept all photos, since I think the training dataset should need on the order of ~5-10,000 photos. It should be achievable while rejecting any problematic photos.

HDPR is a major consideration for this project. I'm working to build in starting points like the ability to delete your data (coming soon) and also to download/export all data users send in.