Simulation Of Ink Diffusion And Water-eroded Ink Footprint On Xuan Paper

The ink diffusion on Xuan paper is a process of ink penetration on paper with strong water absorbency, which usually appears with granular boundary. Simulation of ink diffusion is the basis of realistically simulating handwriting art on Xuan paper involving paper structure and ink attributes.To simulate ink diffusion on Xuan paper, we present a new method based on the diffusion equation with variable coefficient. The diffusion coefficient consists of paper structure and the ink penetration pressure. To describe the characteristics of paper structure, we introduce a weighting fiber structure to model Xuan paper, which regards Xuan paper as mesh fiber structure randomly woven from lines with uniform distribution, and give the relation between types of Xuan paper and fiber weights. Moreover, the function for ink penetration pressure during the diffusion process is also provided. To generate diffusion result efficiently, we propose an implicit difference method with high accuracy to solve diffusion equation. Compared with the previous similar methods, our method is able to describe the spontaneous gray evolution and generate a more natural diffusion boundary. The experimental results demonstrate that our approach can realistically simulate different diffusion effects on different kinds of Xuan paper.The water-eroded ink footprint is different from spontaneous ink diffusion, it is actually a process of two kinds that liquid interact and diffuse on the porous media. To simulate this special diffusion phenomenon, this paper introduces a two-fluid LBE model which takes paper structure, ink concentration and water flow velocity into consideration, and presents a method which transforms particles density distribution to gray value for rendering the eroded ink footprint result.