Q: I have just opened an online store and I have concerns about copyright infringement.

A: Ultimately it depends on where you get the photos and what is in them. If you are using photos that are downloaded from Adobe Stock Photos or a service where the photos are provided to users for posting on public pages, then you might be able to use them, generally. However, if you are finding photos from Google's image search function, or a similar service, then those images may be copyrighted, and downloading them and putting the image on a shirt would be infringement. You also want to make sure that the images do not contain trademarks/registered logos of companies because copying that logo could lead to another liability. If the image has like McDonald's or a big chain, then odds are there is a trademark registered for the logo included, so be cautious.

If you are using a specific platform, such as Adobe, then you also may want to check the terms of service page to see if they forbid you from using their photographs in a certain context. If they do, then you could be found liable for infringing on their rights because you went beyond the scope of their agreement.

When thinking about general copyrightability, what is protectable, it's the expression or creative addition to an existing element or idea. If you take a picture in nature, then the nature scene will not be protectable, but your picture of it captures the scene from a specific perspective, and you can add lighting effects, etc. Your presumedly edited picture of the nature scene is now a copyrightable object. Here is a general list of things that are not copyrightable/protectable by copyright: ideas, systems, generic themes, words/slogans (the fonts of words or design may be copyrightable, though), landscapes, artistic styles/design styles, etc.

Fair use and transformative use are generally a defense that could apply if you are willing to say you did in fact copy the original image of someone, and that work is copyrighted. While fair use has been thrown around a lot, there is much to be determined. If the court does not agree with your specific basis for fair use, then you have already admitted in the record that you copied a copyrighted work, so you can be held liable for copyright infringement. It's a case-by-case basis for analysis, though.