1. An image processing device, comprising: a saturation-enhancement-amount determining device that determines a saturation enhancement amount by extracting saturation information from input image data; a color component extracting device that extracts from the input image data a plurality of color components having saturation to be enhanced; a saturation enhancing device that enhances, based on the saturation enhancement amount determined by the saturation-enhancement-amount determining device, the saturations of the plurality of color component extracted by the color component extracting device; and an enhancement-amount adjusting device that adjusts the determined saturation enhancement amount determined by the saturation-enhancement-amount determining device, such that a color balance in a positive and a negative region of a color space is adjusted, when the saturation enhancing device enhances a saturation of a predetermined color component among the plurality of color components and such that an enhancement amount of the predetermined color component in the negative region of the color space is smaller than an enhancement amount in the positive region thereof, the predetermined color component in the color space being a Cb color component in a YCbCr color space, and an adjusting degree for an enhancement amount in a positive region of the Cb color component being greater than an adjusting degree for an enhancement amount in a negative region of the Cb color component of the YCbCr color space.