Abstract: Physical-based models of ink diffusion are complex, inefficient and difficult to be applied to artistic image transformations.In the paper, an efficient image-based synthesis method for Chinese wash-ink strokes is proposed.A wash-ink stroke is divided into three regions:primary stroke region, diffused region, and irregular boundary region.The diffused region is generated by magnifying the outline of the primary stroke region outward with the same distance.Then the irregular stroke border is created based on the percentage of water of ink and paper properties.To simulate pigment granulation in strokes, we make the statistics in varieties of pixel luminance using hand-painted brush strokes and add the variety errors on the synthesized stroke images.Finally, some applications of using our method to render Chinese wash-ink paintings are introduced.The rendering results show that our method is efficient to synthesize realistic wash-ink brush strokes, and can be used in several fields, such as interactive painting systems, image transformations to wash-ink styles, and wash-ink rendering of three-dimensional scenes.