A METHOD AND APPARATUS FOR CALIBRATING AN IMAGE CAPTURING DEVICE, AND A METHOD AND APPARATUS FOR OUTPUTTING IMAGE FRAMES FROM SEQUENTIALLY CAPTURED IMAGE FRAMES WITH COMPENSATION FOR IMAGE CAPTURE DEVICE OFFSET

摘要

An image vision system (8) for calibrating two cameras (17) mounted on respective side rear view mirror housings (5) of a motor vehicle (1) for correcting for offset of the cameras (17) from ideal positions relative to the vehicle (1). The cameras (17) capture plan view images of the ground on respective opposite sides of the vehicle for display as images (10,11) along with a plan view image (14) of the vehicle (1) on an in-vehicle visual display unit (13), for assisting a driver parking or manoeuvring the vehicle (1 ) in a confined space. Calibration of the cameras (17) is carried out as the side mirror housings (5) are swivelled from a rest position to an operative position in response to activation of the ignition system of the vehicle (1). The calibration requires determining the offset of the actual position of a reference point (34) on the vehicle (1 ) captured in an image by the corresponding camera (17) from the ideal position of the reference point (34a) in an ideal image frame. A transformation function which is expressed as two third order polynomial expressions for the X and Y co-ordinates is produced based on the computed offset for the X and Y co-ordinates of the reference point (34), and a look-up table is then prepared from the two polynomial expressions which indicates the position at which the pixels in the subsequently captured image frames should be located in corresponding output image frames for display on the visual display unit (13) with correction for offset of the corresponding camera (17).