渐近非局部平均图像去噪算法

非局部平均去噪算法(Non-local means denoising algorithm, NLM)是图像处理领域具有里程碑意义的算法, NLM的提出开启了影响深远的非局部方法. 本文从以下两个方面来重新探讨非局部平均算法: 1) 针对NLM算法运算复杂度高的问题, 基于互相关(Cross-correlation, CC)和快速傅里叶变换(Fast Fourier transformation, FFT)构造了一种快速算法; 2) NLM在滤除噪声的同时会模糊图像结构信息, 在强噪声条件下更是如此. 针对这一问题, 提出了一种渐近非局部平均图像去噪算法, 该算法利用方差的性质来控制滤波参数. 数值实验表明, 快速算法较之经典算法, 在标准参数配置下运行速度可提高27倍左右; 渐近非局部平均图像去噪算法较之经典非局部平均图像去噪算法, 去噪效果显著改善.

Asymptotic Non-local Means Image Denoising Algorithm

Non-local means denoising (NLM) algorithm is a milestone algorithm in the field of image processing. The proposal of NLM has opened up the non-local method which has a deep influence. This paper performed a revisit for NLM from two aspects as follows: 1) To alleviate the high computational complexity problem of NLM, a fast algorithm was constructed, which was based on cross-correlation and fast Fourier transform; 2) NLM always blur structures and textures during the noise removal, especially in the case of strong noise. To solve this problem, an asymptotic non-local means (ANLM) image denoising algorithm is put forward, which uses the property of noise variance to control the filtering parameters. Numerical experiments illustrate that the fast algorithm is 27 times faster than classical implementation with standard parameter configuration, and the ANLM obtain better denoising effect than classical NLM.