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基于引导滤波器和局部回归理论的Monte Carlo图像噪声移除算法

Monte Carlo Noise Removal Based on Guided Image Filter and Weighted Local Regression

  • 摘要: 针对现有Monte Carlo(MC)光线跟踪算法中噪声影响大和绘制消耗高的问题,提出一种基于引导滤波器和局部回归理论的自适应绘制算法.首先计算场景特征图像的梯度信息,利用引导滤波器对初始特征图像进行预过滤,以提高诸如景深、运动模糊等特殊绘制效果的图像质量;然后利用局部回归理论进行图像重构,并在图像空间计算最优重构参数,从而避免由含噪特征图像导致的噪声传递问题;最后计算Stein’s unbiased risk estimator(SURE)评判像素复杂程度并引导自适应采样过程.实验结果表明,该算法能够在提高图像视觉质量的同时,有效地降低了噪声影响,并能够绘制高质量的景深、运动模糊等特殊效果.

     

    Abstract: A novel adaptive rendering method based on guided image filter(GIF)and weighted local regression is proposed to remove Monte Carlo(MC)noise while preserving image details.First,GIF is employed to prefilter features when there are complex motions,textures and geometries.In this case,our method produces impressive results for specific effects such as depth of field and motion blur.Second,the images are reconstructed using weighted local theory,which fits the parametric curves in a local space for bias and variance,respectively.As a result,the impact of noise propagation is reduced greatly.Finally,Stein’s unbiased risk estimator(SURE)is adopted to recognize complex pixels and direct the adaptive sampling process.Experimental results demonstrate that our method outperforms prior algorithms in terms of visual image quality and numerical error.In addition,the new method can handle a wide variety of specific distributed effects.

     

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