Brown is a combination of red, yellow and blue. A method of creating brown is discussed at http://www.wikihow.com/Mix-Paint-Colors-to-Make-Brown The contrasting color depends on the colors in the brown you want to contrast. The tertiary color wheel may be helpful with your search. Color Wheel Chart
Taupe.
If you look at a color wheel chart, the opposite of blue is orange.
If you Google the color taupe and view the results you'll notice that there are many colors that go by that name. There is no "official" taupe, so if anyone labels a color they've mixed with that name, it's taupe. Taupe is essentially a light gray (black and white) with just a hint of anything from orange to red to purple in it. I've even seen it with a hint of green.
BEIGE
Since denim is a shade of blue, it would be a complementary shade of orange that is opposite of blue on the color wheel.
On the additive color wheel, the opposite of Orange would be Blue.
On the colour wheel, Blue is opposite of Orange.
Taupe.
the opposite colour to red on the colour wheel is in fact and truely green.
There is no antonym for color wheel.
Colors opposite from each other on the color wheel are called complementary colors.
The specific color that is opposite of white on the color wheel doesn't exist. Most color wheels do not contain the color white on them, if they do it's directly in the center.
The opposite color to yellow on the color wheel is purple. These colors are considered complementary because they are located opposite each other on the color wheel and create a strong visual contrast when used together.
The opposite of gold on the color wheel is purple. Gold is a warm color, while purple is a cool color, making them complementary colors on the color wheel.
The opposite color of green on the color wheel is red.
Complementary colors are colors that are opposite each other on the color wheel.
Each secondary colour is situated opposite the one colour not used in its creation. Therefore the opposite colour to green on the colour wheel is red.