A method is to be implemented by an electronic apparatus having a map database established therein, and includes the steps of: receiving a user-specified input image of an area of interest, and obtaining from the map database a reference map that encompasses the area of interest; selecting a set of feature points in the user-specified input image, and a set of map points in the reference map that correspond in geographical features to the feature points; transforming the user-specified input image according to positional differences between the feature points and the corresponding map points to thereby obtain a to-be-registered image having adjusted feature points corresponding in position to the map points; overlaying the to-be-registered image onto the reference map to thereby obtain a customized composite map image; and outputting the customized composite map image.