1. An image processing device comprising: a representative parallax acquisition unit to acquire representative parallaxes for respective stereoscopic image frames constituting a whole or predetermined partial range of a stereoscopic video; a scene separation unit to separate the stereoscopic video into multiple scenes, when a parallax width does not comply with an allowable parallax width, the parallax width being defined by a maximum value and a minimum value of the representative parallaxes for the respective stereoscopic image frames acquired by the representative parallax acquisition unit, the allowable parallax width being defined by a previously determined maximum allowable parallax and a minimum allowable parallax; a parallax adjustment unit to decide whether a scene parallax width complies with the allowable parallax width, for each of the scenes separated by the scene separation unit, and, in response to the decision result, uniformly adjust the representative parallaxes for the respective stereoscopic image frames constituting the scene such that the scene parallax width complies with the allowable parallax width, the scene parallax width being defined by a maximum value and a minimum value of the representative parallaxes for the respective stereoscopic image frames constituting the scene; and an output unit to output the stereoscopic image frames whose representative parallaxes are adjusted by the parallax adjustment unit, wherein the representative parallaxes for the respective stereoscopic image frames include a statistical operation value to be calculated based on parallaxes that, of parallaxes for the stereoscopic image frames, meet a predetermined condition.