Hands-On Image Processing with Python

Low-pass filter (LPF)

This filter allows only the low frequencies from the frequency domain representation of the image (obtained with DFT), and blocks all high frequencies beyond a cut-off value. The image is reconstructed with inverse DFT, and since the high-frequency components correspond to edges, details, noise, and so on, LPF tends to remove these. The next few sections demonstrate how to use different functions from the numpy, scipy, and scikit-image libraries to implement an LPF and the impact of an LPF on an image.