1. A de-interlacing method comprising: receiving first and third image lines; selecting an upper vector having an N number of pixels among the first image lines, and selecting a lower vector having an N number of pixels among the third image lines; obtaining a weighted value on the basis of a relation between the pixels within the upper vector and a relation between the pixels within the lower vector; selecting an edge direction from the selected upper vector, the selected lower vector, and the obtained weighted value; and interpolating a pixel belonging to a second image line between the first and third image lines on the basis of the selected edge direction.