(eng): We characterize generalized extreme points of compact convex sets. In particular, we show that if the polyconvex hull is convex in $R^{mtimes n}$, $min(m,n)le 2$, then it is constructed from polyconvex extreme points via sequential lamination. Further, we give theorems ensuring equality of the quasiconvex (polyconvex) and the rank-1 convex envelopes of a lower semicontinuous function without explicit convexity assumptions on the quasiconvex (polyconvex) envelope.