This Katy Perry foto contains
schipper, leghorn, panama, hoed, zeeman, skimmer, strooien hoed, livorno, panama hoed, matroos, stro hoed, fedora, vilten hoed, homburg, cowboyhoed, trilby, fedora met vilten hoed, stetson, and sombrero.
There might also be
vierdeukenhoed, campagne hoed, porkpie, porkpie hat, porkpie hoed, bever, and castor.