Hue Obtaining In Painting Simulation Process And Pencil Drawing Research Based On Texture Library

Non-photorealistic rendering (Non-Photorealistic Rendering, NPR) has been rapid development and paid more and more attention in recent years. It has becoming a hot spot of Non-Photorealistic Graphics. Unlike the traditional method of drawing, it's goal is to produce images with artistic effect. As a new research field, NPR is still at the initial stage,and so many aspects of this research still needs further study. It is essential to obtain the basic light and shade hue of scene in non-photorealistic rendering with computer, because it has a direct effect on the final results generated image. It is not necessary to require accurate information for each pixel shading, only grasping the overall light and shade hue of the scene and objects between objects in it is enough.This paper researches on the method of Non-Photorealistic rendering, and puts forward a Non-Photorealistic rendering method which can obtain hue information of the scene and objects in double light source condition.First, this paper summarizes the non-photorealistic rendering technology. Using simulation of the effect of different art as a clue, this paper introduces the non-photorealistic rendering technology of pencil drawing simulation, and there are some analysis and discussion on the characteristic, development and leading arithmetic of this technology. Then, based on previous work, this paper presents a method which can obtain hue information of the scene and objects in double light source condition. The main idea of this method:this method supposes the surface of objects in scene is symmetrically covered with a layer of the same size balls, and two adjacent balls maintain a state of approximate tangent,by computing the ball's sheltered degree by other balls in double light source condition and the approximate mirror reflection information to confirm the hue information of the small ball in it's position. we use these hue informations to control brushstroke's hue at the corresponding position in the process of painting. Finally, this paper also proposes a method of generating pencil drawing based on texture library. (1) Construct a pencil texture library model. (2) Obtain hue information of the scene and objects by using color extraction method proposed in this paper. (3) Determine texture direction in the "point" through selection mechanism. (4) Texture mappingThis method presents a new approach for non-photorealistic pencil charcoal drawing. Simulation results show that it has simple structure, fast computation speed and facilitate the realization the adjustment of local information in scene. The experiment results testify the validity of this method.