1. An image-signal processing apparatus comprising: a setting unit configured to set an eliminating area based on a black bar in an image constituting a moving image, the setting unit including: a black-bar detecting unit configured to detect the black bar in the image based on a low-luminance range in the lines of the image and a border candidate, the border candidate being determined based on an absolute difference of a luminance value between each of a plurality of pixels of the border candidate and pixels of an adjacent line; a motion-vector detecting unit configured to detect an object in the image constituting a moving image and detect a motion vector corresponding to the object using an area excluding the eliminating area in the image; and an estimating unit configured to estimate a position to which the object moves on the basis of the detected motion vector.