Automatic Image-Based Pencil Sketch Rendering

This paper presents an automatic image-based approach for converting greyscale images to pencil sketches, in which strokes follow the image features. The algorithm first extracts a dense direction field automatically using Logical/Linear operators which embody the drawing mechanism. Next, a reconstruction approach based on a sampling-and-interpolation scheme is introduced to generate stroke paths from the direction field. Finally, pencil strokes are rendered along the specified paths with consideration of image tone and artificial illumination. As an important application, the technique is applied to render portraits from images with little user interaction. The experimental results demonstrate that the approach can automatically achieve compelling pencil sketches from reference images. The project is supported by the National Natural Science Funds for Distinguished Young Scholars of China (No.69925204) and Innovative Research Groups (No.60021201). WANG Jin received his M.S. degree in computer application from Zhejiang University in 1999. He is now a Ph.D. candidate at the State Key Lab of CAD&CG at Zhejiang University. His research interests include computer vision, NPR and image processing. BAO Hujun received his Ph.D. degree from Zhejiang University in 1993. He is now a professor at the university. His main research interests are realtime rendering technique, digital geometry processing and field-based surface modeling. ZHOU Weihua received his B.S. degree in engineering and communications from Zhejiang University in 1999. His research interests include computer graphics. PENG Qunsheng received his Ph.D. degree in computer science from East Anglia University in 1983. He is now a professor and the Director of the State Key Lab of CAD&CG at Zhejiang University. His main research interests include realistic image synthesis, 3D modeling and virual reality. XU Yingqing is a researcher of Microsoft China Research. His main research interests include computer graphics, digital geometry processing and virtual reality.