Provided are a method of detecting a transition area and an apparatus for processing an image using the same. The apparatus includes a line representative value calculator configured to calculate line representative values of an image including a non-image display area, an image display area, and a transition area interposed between the non-image display area and the image display area, and a transition area detector configured to calculate first-order and second-order differentiations of the line representative values, calculate a threshold value of the transition area using first-order and second-order-differentiation-representative-values of a first line group including a plurality of lines in a window including a plurality of lines and first-order and second-order-differentiation-representative-values of a second line group including a plurality of lines, and detect the transition area.