White to Black Contour graph

[FernandoRios]

Dear all,
I wonder If anyone has a tip on how to produce a contour graph that transitions from white to black.
Here is the code I have:

sysuse sandstone, clear
* this one is the closest of what i want, but i would prefer to have the base color to be white
 twoway contour depth northing easting, scheme(s2mono)
* So I tried something like this, but without success
 twoway contour depth northing easting, scolor(white) ecolor(black)

I would appreciate any suggestions.
Thank you
Fernando

[Scott Merryman]

The default contour rule is equally spaced hues. I don't believe black or white have a hue. Using the linear crule option seems to work:

twoway contour depth northing easting, crule(linear) scolor(white) ecolor(black)  scheme(s2mono)

[FernandoRios]

Perfect! Thank you!