如何在python中显示中值灰度图像？

I have an image and I find median and deviation in blocks of 5*5 in my image and save it to the and images. now when I show the results they are mask of the original image while it should not be so. it should show me a blur image in gray level not black and white!!. Do you know what mistake I have made?I have an image and I find median and deviation