1. An image processing apparatus, comprising: a processed image generation unit configured to acquire an image around a vehicle picked up by a camera provided on the vehicle, and generate a processed image from the image for target object detection processing; a provisional detection unit configured to scan a scanning frame of a predetermined size according to a detection target object on the processed image, and detect a plurality of position candidate regions of the detection target object within the processed image by determining a feature value for respective scanning positions using a dictionary of the detection target object; and a final detection unit configured to determine an overlapping region of the plurality of position candidate regions, and determine a final detection position of the detection target object within the processed image based on the overlapping region and the plurality of position candidate regions.