A method and apparatus enhances an image quality where original brightness data Xij of a concerned pixel is compared with predetermined brightness levels X1 and X2, which are reference variables to obtain new brightness data Yij, with an enhanced contrast. The method sets initial values of a parameter V.sub.b to calculate the brightness level X1, a parameter V.sub.p to calculate the brightness level X2, the brightness level X1, and the brightness level X2, and compares the brightness data Xij with V.sub.b and V.sub.p. The method resets V.sub.b and V.sub.p according to comparison results and identifies a background area according to the comparison results between the brightness data Xij and parameter X1 or X2, and performs the contrast enhancement on pixels belonging to the background area, and updates the brightness levels X1 and X2 using V.sub.b and V.sub.p when the concerned pixel is the last one in the concerned line.