McGibney G, Smith M R
Department of Electrical and Computer Engineering, University of Calgary, Alberta, Canada.
Med Phys. 1993 Jul-Aug;20(4):1077-8. doi: 10.1118/1.597004.
Estimating the true signal-to-noise ratio (SNR) of magnetic resonance (MR) images with low signal is confounded by the magnitude presentation of the data. This paper suggests a simple solution to this problem. A common method of measuring SNR compares the mean signal to the standard deviation of the noise. This SNR measure was found to be satisfactory for high but not low signal-to-noise image regions because of noise bias. These inconsistencies are removed by introducing unbiased definitions of the signal and noise levels in terms of their root-mean-square values. The approaches are compared by evaluating the SNR values for MR medical images.
估计低信号磁共振（MR）图像的真实信噪比（SNR）会因数据的幅度表示而变得复杂。本文提出了一个解决该问题的简单方法。一种常见的测量信噪比的方法是将平均信号与噪声的标准差进行比较。由于噪声偏差，这种信噪比测量方法对于高信噪比图像区域是令人满意的，但对于低信噪比图像区域则不然。通过引入基于均方根值的信号和噪声水平的无偏定义，消除了这些不一致性。通过评估MR医学图像的信噪比来比较这些方法。
