1. An apparatus for converting a monochrome image to an estimated color image so as to display the estimated color image, the apparatus comprising: a camera which is configured to be mounted on a vehicle and which photographs: a view from the vehicle and outputs the monochrome image which includes a background, a road, a left view, and right view; an edge image generating portion which detects edges in the monochrome image to generate an edge image indicative of the detected edges only; a four-division portion which divides the edge image into four areas, an upper area corresponding to the background, a lower area corresponding to the road, a left area corresponding to the left view and a right area corresponding to the right view with two cross lines; a white line recognizing portion which recognizes a white line on the road in accordance with the edge image in the lower area; an object determining portion which determines an object forming the edge image in each of the upper, left and right areas; and an estimated color image making portion which assigns a color to each white line recognized by the white line recognizing portion and the object determined by the object determining portion for each of the upper, left and right areas in order to make the estimated color image.