OK, but the photo is from 1967, and the poster is from 1968. That was more into the really long hair version of the hippie, wasn't it? Or was that not until the 1970s?
It's hard to fathom that what is now the normal-young-person look used to be so radical. Or that it was forged in a handful of years, an astonishingly short time. That's another thing about the photo collection I mentioned: to our eye, the kids all look normal. Deviant social experiment is the last thing that comes to mind.
I note that the musical Hair came out in 1967.