Research On NPR Pencil Drawing Generation Technology

Non-photorealistic rendering is a part of computer graphics. Since the mid-1990s,non-photorealistic rendering gradually becomes one of the research hotpots of thecomputer graphics. Non-photorealistic rendering is the technology of using computerto generate non-photorealistic but hand-drawn style graphics. Its target is not theauthenticity of the graphics, but to show the artistic nature of the graphics andsimulate the art works. As the effective supplement of realistic graphics,Non-photorealistic rendering greatly enriches the research on computer graphics.Non-photorealistic rendering technique can generate a variety of artistic effects, suchas oil painting, watercolor, ink and wash painting, pen drawing, and can even simulatethe artist’s paintings and styles. With the development of non-photorealistic renderingtechnology, people apply this technology to simulate pencil drawing, which hasbecome a research hotspot of non-photorealistic rendering. The rendering of pencildrawing aims at generating a natural, smooth, simple, and crisp effect through the linewith different shading effects and the different tones of the pencil.The main work of this paper includes: we do research on the development statusof non-photorealistic rendering technology, especially on the development status ofpencil drawing in non-photorealistic rendering; we also do research on several imageprocessing theroies and methods in pencil drawing generation technology; weimprove the existing generation method of pencil drawing; we propose a fast pencildrawing generation method based on image grayscale stratified.The innovation of this paper in the following aspects:1. This paper uses a new contour edge detection method superior to the traditional.Based on the neon method, we deal the image in the HSV color space and realize theprocess of outlining the contours of the image. This method makes the contour linesof the pencil drawings have a light and shade effect, and the color is no longer a single.Compared with other contour extraction methods, the proposed method can get bettercontour effect.2. This paper proposes a fast pencil drawing generation method based on imagegrayscale stratified. According to gray scale value of each pixel we divide the imageinto different layers. This method not only can generate a better pencil drawing effect, but also speed up the generation process, as a result, it improves the efficiency of thepencil drawing generation.3. This paper extends the pencil drawing effect to color image space and dynamicvideo scenes. Although the research on the pencil drawing constantly goes deeper,there is a few algorithms of the research on color pencil drawing and video pencildrawing. This paper applies the generation method of pencil drawing to color pencildrawing rendering and video pencil drawing and we get the dynamic video effects ofpencil drawing.