An Improved ETF Model And Its Application In Simulation Of Out-of-Print Woodcut

Non-Photorealistic Rendering (NPR)technology is one of the most popular research directions in the field of computer graphics. NPR has the extensive applications and the giant market prospect,its mapping results often bring people the huge visual impact and the rich imagination,research results have appeared in oil painting,gouache,pencil drawing,cartoons,etc,but there is only a few simulation studies of woodcuts.As a rookie in the printmaking community,The Yunnan out-of-print woodcut is a new technique emerging at the80s of last century, which is gradually evolved from the chromatic woodcut overprint. As it follows the principle of "a version sets are in turn overprinting", the out-of-print color overlaying woodcut can produce special effects of color overlap with heavy and loud color. The woodcut is very attractive and has local characteristics and humanistic value. The simulation for the Yunnan out-of-print woodcut has the great cultural significance,it can surely show the chinese characteristic culture to rich the field of chinese non-photorealistic rendering.The thesis introduces some existing simulation methods of non-photorealistic rendering technology and woodcut.the simulation for woodcuts can be from the3d or2d space,due to the simulation for three-dimensional physical process with complex interactions,complex calculation,the big workload and the bad real-time performance, so processing real images to generate outcomes of woodcuts from two-dimensional space dominates in real time.Therefore, this thesis chooses to generate woodcuts corresponding to2d images from two-dimensional space. The thesis is based on samples of nicks to simulate the woodcut out of print for overlay,this method makes the generated woodcuts have a variety of nicks,compared with the existing method for stylized woodcuts of Mello etc,it can reflects the advantage of diversified nicks.The method based on streamline generating nicks proposed in the thesis is more flexible than the method for texture synthesis,it can reflect the direction of texture in the original image.The method based on streamline automatically generates multiple nicks once,every nick adjusts the direction automatically according to the flow direction,and the style of the nick is optional.This method can not only reduce the workload of pasting nicks but also make the nick reflect the direction of original texture. This thesis proposes a method for simulating black and white woodcuts, through experiments,the effect of simulating is good.The thesis mainly includes the following several aspects:First of all, this thesis makes an improvement to ETF model,oil painting with the abstract local linear feature and the stylized edge can be generated by using the improved ETF model proposed by this thesis, this thesis simulates the edge of woodcuts by using the stylized edge with the abstract feature.Second,large regular nicks can be generated by taking advantage of texture synthesis technique based on the sample figures and the nicks, these nicks can simulate the background of woodcuts.The area with the unstable variation in direction of texture can be simulated by using the method of generating nicks based on the streamline proposed by this thesis.Discontinuous edges with the indented style also can be simulated by using this method.Nicks are optional in the above methods, these methods show the advantage of diverse nicks.Third, this thesis proposes a method for simulating black and white woodcuts,this method uses the techniques including texture synthesis, the stylized edge and generating nicks based on streamline to generate the effect of woodcuts corresponding to the real images.