(* Sorry about the mixup in the code the I posted. The cut and paste function somehow missed up the translation and left out a bunch of stuff. I think this post is correct. It shows my problem with the colors of the level curves. *)
a = 0; b = 1; c = 0; d = 2;
f[x, y] := Sin[Pi x]^2 Sin[Pi y]^2;
p1 = ContourPlot[f[x, y], {x, a,
b}, {y, c, d}, ContourShading -> False, AspectRatio -> Automatic,
Contours -> {.7}, PlotPoints -> 100, ContourStyle -> RGBColor[1, 0, 1],
AspectRatio -> 1];
p2 = ContourPlot[f[x, y], {x, a, b}, {y, c, d}, ContourShading ->
False, AspectRatio -> Automatic, Contours -> {.9}, PlotPoints ->
100, ContourStyle -> RGBColor[1, 0, 1],
AspectRatio -> 1];
p3 = ContourPlot[f[x,
y], {x, 0, 1}, {y, 0, 2}, ContourShading -> None, AspectRatio ->
Automatic, Contours -> {0, .5, .7, .9}, PlotPoints -> 100,
ColorFunction -> {RGBColor[0, 0, 0], RGBColor[1, 1, 0], RGBColor[
0, 1, 0], GBColor[0, 0, 1]},
ContourStyle -> {RGBColor[0, 0, 0], RGBColor[1,
1, 0], RGBColor[0, 1, 0], GBColor[0, 0, 1]},
AspectRatio -> 1]