An image processing device includes an edge direction determination unit, a filter coefficient calculation unit, and a filter processing unit. The edge direction determination unit determines a first edge direction of an edge including a first pixel of input image data, and calculates a first reliability value of the determined edge direction corresponding to the first pixel. The filter coefficient calculation unit calculates a first filter coefficient corresponding to the first pixel, a second filter coefficient corresponding to a second pixel, and a third filter coefficient corresponding to a third pixel at least based on the first reliability value of the first edge direction. The filter processing unit performs filter processing on the input image data on the basis of the calculated first through third filter coefficients, and outputs output image data.