Binarize

Binarize[image]: gives a binarized version of image, in which each pixel is either 0 or 1.
Binarize[image, t]: map values x > t to 1, and values x <= t to 0.
Binarize[image, {$t_1$, $t_2$}]: map $t_1$ < x < $t_2$ to 1, and all other values to 0.