The Image of a function is set of all numbers, which can be obtain from a formula of a function. The Image of a function can be obtain from graph of a function too. Denoted by Imf, Im_f, Y. Examples. y = x^2, Im_f = [0,∞), because a square power of number is greater or equal than to 0. y = x+1, ZW = R, because can obtain any number put a right number to a formula.