A method of alerting a vehicle's driver. The method comprises receiving a first set of image data imaging a driver's perspective, the first set of image data captured by at least one image sensor coupled to a primary device placed on the driver and directed outwardly from the driver, receiving a second set of image data, the second set of image data captured by a second device mounted on a vehicle driven by the driver, processing the first and second sets of image data to determine a comparison result, the comparison result determined according to image similarity between the first and second sets of image data, generating an alert according to the comparison result, and automatically presenting the alert to the driver
