there are 3 types of intellectual property rights:
patents, copyrights, and trademarks
copyrights are for printed material. things are technically automatically copyrighted as soon as they are printed/produced.
patents are for original ideas (inventions). you have to apply for a patent for your idea.
and trademarks are signs, symbols, phrases, etc. that associate a product/good with another person/brand/company/etc.
so, after having looked at that, you can see that taking a picture of someone in public really has nothing to do with intellectual property rights, being that the photo is the subject of the magazine, not the magazine itself. (e.g. if someone started naming their magazine 'britney spears magazine" or something, they'd get their asses sued off.)