1. A method of using road signs to augment Global Positioning System (GPS) coordinate data for calculating a current position of a personal navigation device, the method comprising: obtaining recent GPS coordinate data with the personal navigation device; obtaining a real-time image from a camera of the personal navigation device while the personal navigation device is changing its current position, the real-time image showing areas surrounding a road on which the personal navigation device is traveling; recognizing a road sign in the real-time image by performing image processing on the real-time image; and using a known position of the road sign to augment the recent GPS coordinate data in order to more precisely determine the current position of the personal navigation device.