关键词: 自然图像抠图, 蓝屏抠图, 有重启概率的随机游走（RWR）

Abstract: A new natural image matting method is proposed based on the graph theory.This algorithm begins from the image mapped into a weighted undirected graph and marks seeds in the graph with different colors，then uses the random Walk with Restart algorithm to calculate similarity of the pixels，and proposes a linear model.Finally，the problem is solved and the foreground and background color components of each unknown point are estimated.Experimental results have shown that the proposed method has many advantages.The RWR method is quoted in the natural image matting with the use of graph theory.It avoids the high complexity of the inverse in image and solves the weak boundary problem.

Key words: natural image matting, blue screen matting, Random Walk with Restart