Jin Wang Hujun Bao Weihua Zhou Qunsheng Peng Yingqing Xu Automatic Image-Based Pencil Sketch Rendering. 347-355 2002 17 J. Comput. Sci. Technol. 3 http://jcst.ict.ac.cn/cone/cone23.html#paper11 db/journals/jcst/jcst17.html#WangBZPX02