In a word, the method of this paper is an efficient edge detection algorithm for detecting edges from noised image.

总之，该算法能有效地从噪声图像中检测出边缘。

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The traditional way is to obtain the sub-image by sampling the noised image in spatial or frequency domain, then calculate its variance to replace that of the original noise.

传统方法是通过空域或频域采样，得到该子噪声图像，然后直接对其估计方差，它对图像信息的分布有要求。

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Variance estimation is a common problem in noised image processing. The basic idea is to get a sub-image that includes only "pure" noise to estimate the variance of original noise.

噪声的方差估计是含噪图像处理中的常见问题之一，其基本思想是通过某种方法寻找含噪图像中的“纯”噪声子图像来估计原噪声方差。

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