The present invention discloses an image processing device and an image processing method. The image processing method includes steps of: referring to multiple frames or an auxiliary data associated with the frames to determine whether the frames contain substantially the same frames; selecting the frames according to whether the frames contain substantially the same frames to generate multiple selected frames; and performing video processing on the selected frames. When the frames do not contain substantially the same frames, the selected frames are the same as the frames, and when the frames contain substantially the same frames, the selected frames are part of the frames.