Formulas are derived in this
paper for the conjugates of convex integral functionals on Banach spaces of
measurable or continuous vector-valued functions. These formulas imply the
weak compactness of certain convex sets of summable functions, and they
thus have applications in the existence theory and duality theory for various
optimization problems. They also yield formulas for the subdifferentials of integral
functionals, as well as characterizations of supporting hyperplanes and normal
cones.