Hands-On Image Processing with Python

Using the median filter

The median filter replaces each pixel with the median of the values of its neighbor pixels. This filter is great for removing of salt-and-pepper noise, although it removes small details from the image. We need to give first rank to the neighborhood intensities and then select the middle value. Median filtering is resilient to statistical outliers, incurs less blurring, and is simple to implement. The following code block shows how the PIL ImageFilter module's MedianFilter() function can be used to remove salt-and-pepper noise from the noisy mandrill image, with different levels of noise added and a different size of the kernel window used for the median filter:

i = 1pylab.figure(figsize=(25,35))for prop_noise in np.linspace(0.05,0.3,3): ...