An image processing apparatus is provided, including a brightness change level classifying unit, a dynamic weight calculating unit, and a brightness correcting unit. The brightness change level classifying unit compares a brightness change average value representing brightness changes from a pixel of interest to neighboring pixels around the pixel of interest with an upper threshold value and a lower threshold value and classifies the brightness change level of the pixel of interest into three types of levels according to the result of the comparison. An upper threshold value and a lower threshold value are predetermined based on the brightness of the pixel of interest. The dynamic weight calculating unit calculates different dynamic weights according to the brightness change level of the pixel of interest. The brightness correcting unit corrects the brightness of the pixel of interest, based on the dynamic weights. Accordingly, noise generated on a plane part of an image is minimized and a contour of the image is appropriately emphasized, consequently improving the definition of images.