An apparatus includes a storage unit configured to store an attribute of each pixel existing inside a tracking target area set on an image and an attribute of a pixel existing adjacent to the pixel, an allocation unit configured to allocate an evaluation value to a pixel to be evaluated according to a result of comparison between an attribute of the pixel to be evaluated and an attribute of a pixel existing inside the tracking target area and a result of comparison between an attribute of a pixel existing adjacent to the pixel to be evaluated and an attribute of a pixel existing adjacent to the pixel existing inside the tracking target area, and a changing unit configured to change the tracking target area based on the allocated evaluation value.