An image processing device includes an input unit, a detecting unit, a calculating unit, and a determining unit. The input unit is configured to receive a recognized image representing an object. The detecting unit is configured to detect at least one surface of the object from a corresponding recognized image corresponding to the recognized image, the corresponding recognized image being on a frequency image indicating frequencies on a plane, the frequencies being of distance values corresponding to pixels of the recognized image. The calculating unit is configured to calculate an angle of the at least one surface with respect to a predetermined direction. The determining unit is configured to determine, based on the at least one surface detected by the detecting unit and the angle calculated by the calculating unit, whether or not the recognized image is to be rejected.