According to the frequency filter shown in FIG. 4B, the origin point and two points adjacent to the origin point have a value of 1 (that is, the filter value from the origin point to the boundary line is 1), and the other points have a value of 0 (that is, the filter value beyond the boundary line is 0). Also, as described above, applying of the filter may denote that the locations corresponding to the frequency components are multiplied by the filter value of the corresponding locations, and thus, the magnitudes of the frequency components only at the origin point and two points adjacent to the origin point may remain as application results of the frequency filter.

In addition, the above values ‘1’ and ‘0’ are examples, and the frequency filter may have different values according to design. For example, a value ‘1.0001’ may be used instead of the value ‘1’, and a value ‘0.0001’ may be used instead of the value ‘0’. However, the inventive concept is not limited to the above examples.

In addition, the controller 130 according to the embodiment may generate an output image based on the one or more frequency components, to which the frequency filter is applied. For example, the controller 130 may perform an inverse discrete cosine transformation (IDCT) on the one or more frequency components, to which the frequency filter is applied, to transform the one or more frequency components into the output image. Here, the output image may be an image block unit image or a frame unit image.