An image processing apparatus includes a designator which designates each of one or more characteristic images included in a scene image as a reference characteristic image. Located to the rear of the intake and mowing drums for receiving crop delivered to the rear by them are a pair of slope conveyor drums respectively located on opposite sides of a longitudinal center plane of the header and at opposite sides of an inlet passage leading to feed rolls for introducing the crop into a chopper drum of the harvester. The secondary gate member can be located in the cavity of the primary gate member and configured to move relative to the primary gate member and the frame within that cavity. Each of the movable guides is formed in a shape that the width thereof gradually decreases from the outer end toward the inner end. The beams are configured to engage opposite sides of the blade contact when the blade contact is mated with the terminal.