1. An image correction apparatus comprising: a feature-value calculating unit that calculates a feature value indicative of average brightness of an input image from pixel values of pixels of the input image; a boundary determining unit that determines a pixel value at a boundary for correcting each pixel of the input image to make the pixel brighter or darker by using the feature value of the input image calculated by the feature-value calculating unit; and a correction-amount calculating unit that calculates, with respect to the pixel value of each pixel of the input image, an area for determining a contrast correction amount for a pixel value smaller than the pixel value at the boundary determined by the boundary determining unit such that a pixel is to be made darker, and an area for determining a contrast correction amount for a pixel value larger than the pixel value at the boundary determined by the boundary determining unit such that a pixel is to be made brighter.