In 1968, art students Storm Thorgerson and Aubrey “Po” Powell made a trippy photo collage for their musician friends Syd, David and Roger. The resulting album and album cover, A Saucerful of Secrets, helped launch two careers: that of Pink Floyd, one of the 70s megabands, and of Hipgnosis, which, over the course of the next 25 years, designed a stream of iconic album covers.