Abstract: An aspect of the present invention provides a data processing apparatus, including: an image acquisition section that acquires a captured image depicting a road along which vehicles pass; a calibration section that computes a road parameter for converting coordinates in the captured image to coordinates in real space based on the captured image and road data related to the road; a vehicle lane region detection section that detects a vehicle lane region in the captured image based on the captured image and the road parameter; and a processing region setting section that, based on the vehicle lane region, sets a processing region in the vehicle lane region for detecting a vehicle passing.