Nope. All brush work.
For color-picking, it's all about the environment. For example, the desert one, I used cooler colors for the shadows, since the shadows are getting some light from the sky, and I used more saturated, yellow-tinted colors for the light.
The last one uses darker, and a bit more saturated colors for the shadows, and slightly lighter but less saturated colors for the lights.
Murry's Colour Constructor
is a huge help.