1. A computer-readable medium configured to store a computer program that performs a method of detecting a road sign in an image for development of a navigation database, the method comprising: receiving a plurality of images of roads, the plurality of images captured via a camera mounted on a vehicle; determining scale-invariant features of each of the plurality of images, the scale-invariant features determined as a function of a scale-invariant feature transform; comparing the determined scale-invariant features with reference scale-invariant features to determine whether a road sign is included in at least one of the plurality of images, the reference scale-invariant features corresponding to a text character; and identifying at least one of the plurality of images determined to include the road sign as a function of the comparison between the determined scale-invariant features and the reference scale-invariant features, the road sign including the text character.