对磁共振图像数据进行费米滤波，对滤波后图像进行边缘区域和图像区域的选取，并分别对两者进行均值和标准差的计算，最后得出信噪比。-For magnetic resonance images, we can　use a Fermi 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 .