Automatic Generation of Pencil Sketch for 2D Images

Non-Photo-Realistic Rendering (NPR) is becoming increasingly important research topic in computer graphics and image processing. This paper puts forward a novel method for automatically generating a pencil sketch from a real 2D color image in non-photo-realistic rendering. First of all, the edge of the color image is detected by Sobel operator. Secondly, the color image is sharpened by Unsharp Mask (USM), then color scaling is used to get an image with radial and edge details. Furthermore, the original image is divided into many meaningful regions using an efficient method of image segmentation, then the texture direction is determined by Fourier transform and shape feature. To render better effects of illumination and local texture of pencil sketch, the Line Integral Convolution (LIC) algorithm is applied and combined color scaling and white noise image. At last, the pencil sketch is created and the generation results from the superposition of the edge, the USM image and the texture. The experimental results prove that our approach could efficiently generate more obvious edge, more natural tone and more real texture than existed methods.