I agree on the sixties, but for different reasons.  I also must add that you probably mean Blow Up rather than the 1981 Blow Out.  In my opinion foreign film never got better with 8 1/2, La Dolce Vita, Sergio Leone's Dollars Trilogy, Jules and Jim, The Weekend, and numerous others.  On the American side it saw 2001, Lawrence of Arabia, The Manchurian Candidate, the Graduate,and Psycho.