1. An image capturing device comprising: a distance image sensor; a luminance image sensor; an external parameter estimating unit for estimating external parameters using a distance image obtained by the distance image sensor and a luminance image obtained by the luminance image sensor; a corresponding pixel determining unit for determining a correspondence relationship between pixel positions in the distance image and pixel positions in the luminance image, using previously stored internal parameters of the distance image sensor and the luminance image sensor, and the external parameters; and an occlusion searching unit for searching for an occlusion region in the distance image, using the correspondence relationship between pixel positions in the distance image and pixel positions in the luminance image determined by the corresponding pixel determining unit.