1. An image-capturing apparatus comprising: an image-capturing section capturing an object, which is rectangular; a display section displaying a captured image, which is an image captured by the image-capturing section; an output target image determining section determining, as an output target image, the captured image displayed on the display section at a designated timing; a detecting section detecting groups of edge pixels arranged in a shape of a line segment on the image captured by the image-capturing section; and a display processing section causing a contour line representative of a contour of the object to be displayed on the captured image displayed on the display section in such a manner that the contour line is superimposed on the groups of edge pixels detected by the detecting section.