See specific code: https://blog.csdn.net/qq_30263737/article/details/91579005
Custom filters the frequency domain, it results quite passable, the right side is very obvious.
Fourier transformation is to take an unlimited amount of time to analyze the frequency, not reflect the relationship between frequency and time, is overall statistical frequency image, the image can not be analyzed locally, so the right side of the local unevenness can not be satisfactory gradation the result of.
Original:
Fourier transform:
Area selection:
result:
