So it is ok for bloggers, journalists, fan sites, meme sites, meme factories etc. To take someone's publicly posted pic and use it for amusement or personal gai

So it is ok for bloggers, journalists, fan sites, meme sites, meme factories etc. To take someone's publicly posted pic and use it for amusement or personal gain? But it is not ok for a group of collectors to organize collections on internet out of crops of publicy posted photos, for something completely legal?