1. A method for generating a signal based on a visual image, the method comprising: photographing a target object with a digital camera to obtain a target image; receiving the target image into a processor that is in communication with the camera; cross-correlating the target image with a plurality of structures each having a different radius value across the target image to generate coordinate points; extracting icons from the coordinate points generated by the cross-correlating of the target image, wherein the extracted icon size is proportional to the respective radius value of the structure having a predetermined cross-correlation match value; normalizing each icon to a predetermined constant size; comparing at least one normalized icon to stored icons associated with learned images to determine a match; and generating a signal for output on a device associated with the camera.