TeX-Beamer colors

To define colors in tikz,

\draw[color={rgb:red,4;green,2;yellow,1},ultra thick, rounded corners] (0.12,0.00);
or

\draw[black!40!green,ultra thick, rounded corners] (0.12,0.00) rectangle (0.28,1.00);

http://tex.stackexchange.com/questions/24434/how-to-specify-a-fill-color-in-rgb-format-in-a-node-in-tikzpicture