Image-processing device and vehicle system

Provided is an image-processing device, equipped with: an image input unit into which is inputted an image obtained by imaging, by means of an imaging unit equipped with a lens, a subject that includes a light source on board a vehicle to be measured; a high-luminance area detection unit for extracting from an image an area of luminance higher than a threshold value as a light source area corresponding to the light source; a light source center calculation unit for calculating, on the basis of a light source area, a light source center that corresponds to the center position of the light source in the image; and an actual distance calculation unit for calculating the distance from the imaging unit to the vehicle to be measured, on the basis of the position of the light source center and the focal distance of the lens.