对于磁共振图像，使用高斯滤波器对图像进行滤波，对滤波后的图像进行边缘和图像区域的选取，计算两者的均值和标准差，最后得到新的信噪比值。-For magnetic resonance images, we can　use a Gaussian filter to the image for filtering. After the selection of the area of the air and the area of the image,then calculate the mean　value and standard deviation value of both. Finally ,we can obtain the conclusion the new SNR value .