“…NPR techniques create more impressive images than the photorealistic rendering does, thus a promising technique to be used in the computer games, movies, and other entertainment fields which tend to place emphasis on the visual impact. A number of NPR methods have been proposed including silhouette-based methods [5,14], pen-and-ink methods [8,20], colored pencil drawing [21], wax crayons [19], stylized rendering [2,4,7], mosaics creation [6,9], and so on.…”