Abstract:

To analyze the feature vectors of vehicle plate characters and its extraction method, this paper proposed a linear similarity function definition sim(M,N) based on cityblock distance, discussed the properties of this similarity function, and gave the mathematic explanation of completely dissimilarity. Compared with some common similarity functions,sim(M,N)can describe feature vector differences linearly and the computation is very easy. Meanwhile, the paper discussed the differences between Euclidean distance and sim(M,N) in analyzing feature vector differences, and proved the shortage of Euclidean distance through experiments. In the average character margin experiment of similar vehicle plate characters, sim(M,N) is demonstrated to be better than other similarity functions.         

Key words: linear similarity function;average character margin;character feature vector