(* Contour plot of Cos[x^3  y^3]Exp[-Abs[Tan[x y]]] in the
   rectangle 2 <= x <= 5, -5 <= y <= -2)                     *)

ContourPlot[
    Cos[x^3  y^3]Exp[-Abs[Tan[x y]]], {x, 2, 5}, {y, -5, -2},
     PlotPoints -> 300, Contours -> 10, ContourLines -> False,
     ColorFunction -> GrayLevel, Frame -> False, AspectRatio -> 0.9];