Patent claim: An object detection device characterized by comprising an imaging unit 400 that is mounted on a movable body an object detection unit 202 203 that calculates an image displacement of a partial image between two images captured by the imaging unit 400 at different times and performs detection processing to detect an object from an image based on at least the image displacement and a control unit 202 203 that changes a manner of performing the detection processing based on a position in the image in a lateral direction of the movable body wherein the object detection unit 202 203 performs first detection processing to detect the object based on a shape of the object and second detection processing to detect the object based on the image displacement the control unit 202 203 switches between the first detection processing and the second detection processing based on the position in the image in the lateral direction the control unit 202 203 determines whether a positional deviation between the position in the image in the lateral direction and a center position of the image in the lateral direction is less than a first threshold and the control unit 202 203 performs the first detection processing in a region in which the positional deviation is less than the first threshold and performs the second detection processing in a region in which the positional deviation is equal to or greater than the first threshold.

Related passage: So that the detection device may work appropriately the image capture speed should preferably be in excess of 40 images per secondsince in this way the device is capable of following the trajectory of the approaching vehicles with greater accuracy.The detection device algorithm has four main modules basicallyAn optical flow detection module.The algorithm uses a technique based on phase differences to produce a dense estimate of the optical flow in the direction of the axis of the road.To this end a pair of successive images is processed.Visual elements that are not moving forward are filtered and eliminated.The resulting images are fed to the following modules.This module is optional and may be not used.Vehicle detection and followup module.In the region defined by the mask the algorithm calculates the arrises of the image and their directions.The vertical arrises and the horizontal arrises are normalized and integrated along the vertical and horizontal axes respectively.The normalization factor is adjusted dynamically based on the average density of the arris.The unidirectional projection of said arrises on the corresponding coordinates axis is used to trace the trajectory according to said axis.Approaching objects generate projections with positive speeds that is to say to the right and downwardly of the image.These points are separated from other points that are stationary or have relative movements with the aid of directional filters.The resulting trajectories are identified and selected.Module for detection of vehicles without relative speed.Once the trajectory of an approaching vehicle has been identified by means of the displacement of its corresponding unidirectional projections the speed of the vehicle is estimated and supervised.Therefore it is possible to detect situations in which this approaching vehicle reduces speed and circulates at the same speed as the vehicle fitted with the device staying at a short distance from the vehicle fitted with the device.In these cases it is possible to emit a specific type of alarm signal until substantial changes dropping behind or overtaking the vehicle fitted with the detection device are observed in the environment of the image of the approaching vehicle.In other words this module allows for control of traffic situations for example dense traffic where parallel circulation takes place namely vehiclescirculating in different lanes at practically the same speed.In these cases it is relatively frequent for a vehicle to be positioned in the blind spot of another vehicle which may generate situations of danger.Left turn detection module.During left turns there occurs a constant overall displacement of the visual elements contained in different images.The constant displacements are detected in the upper portion of successive images by means of a correlations technique.The coherence of this signal during a number of successive images is used as an indication that the vehicle fitted with the device is turning and therefore that the left turn detection module should be activated.