Research On Interactive Digital Synthesis Of Yunnan Out-of-print Woodcuts

Non-Photorealistic Rendering(NPR) technology is one of the most popular research directions in computer graphics field. NPR not only has the widely applications but also has a giant market prospect, its results bring people many huge visual impacts and the unlimited imagination. NPR technology has a good research in painting, pencil, ink, cartoons, etc., but there are only a few researches and simulations on woodcuts.Yunnan out-of-print woodcut is a special art form of traditional woodcuts, it was took off in Simao which is a city of Yunnan province in1980s. Yunnan out-of-print woodcut is evolved from the traditional chromatic woodcut overprint, and breaks through the limitation of traditional woodcuts. It follows the principle of "a version sets are in turn overprinting", engraving then printing and engraving the second time then printing second time and so on which in only one wood planks. So, it can produce many beautiful special effects of colors overlap. Because of it must engrave another time after printing, we can not reserve the previous edition, so called the out-of-print. Yunnan out-of-print woodcut is a typical representative of Yunnan local minorities’artistic characteristics and has very artistic value. Digital synthesis of Yunnan out-of-print woodcuts no only solved the problem of "out-of-print", but also preserved and inherited this kind of Chinese traditional cultures.According to the actual working process of Yunnan out-of-print woodcuts, a technique of interactive digital synthesis of Yunnan out-of-print woodcuts is proposed. The thesis’main works include the following three aspects:First of all, extract scores from the real woodcuts images with improved Closed-Form Solution, and establish scores libraries according to the different kind of gravers. The thesis also provide a tool to edit the score interactively, thus the nicks can be distorted, rotated and zoomed easily by users.Secondly, the thesis comes up with an interactive simulation of the real creation process of engraving which includes simulating different woodcuts appearances for printing with color quantization, simulating operation of graver with placing scores, simulating engrave the simple and repeated score patterns with texture mapping.Thirdly, the thesis puts forward a simulation of the process of printing. The thesis simulate the process of color-printing and achieve the effect of color fusion; We provide an interactive color transfer tool which can convert different colors and styles according to the existing out-of-print woodcut works; We can extract and color the abstract edges and enhance the contours of the digital synthesis results with these abstract edges, thus the synthesis results look more vivid.Finally, we compare and analyze our synthesis results with the results of other existing methods and also the real woodcuts art works. We conclude that our approach veritably simulates the manufacture process of the Yunnan out-of-print woodcuts, our synthesis results are more satisfactory, and more close to the real Yunnan out-of-print works.