Rough edge detection of low contrast images using consequential local variance maxima

This paper suggests a new edge detection method using local variance maxima which can be applied for finding an auto license plate (ALP) with over 98% success rate in a practical situation. We determine whether a certain point belongs to an edge or not by its length of consequential local variance maxima instead of its magnitude. This is a distinguished difference from the other edge detection methods. The proposed method works effectively even for images of low contrast. This method finds edges by a single pass, with line by line scanning that means no preprocessing and small time consumption