I'm studying image processing and I know that there are different filters you can apply. I don't understand the difference between the low-pass/bandpass/notch filter (or high-pass/band-reject/notch). I tried to draw them but I don't know if I did it correctly:
From what I have realized it is that the difference between a low-pass filter and a band-pass is that the first is symmetrical with respect to the y axis while the second is not. Therefore, a low-pass filter passes the lower frequencies and resets those higher than a certain threshold (cutoff frequency). Instead, a band-pass filter passes the frequencies included in a certain range and cancels the others. It's correct?
But I have not really understood the purpose of the notch filters. I realized that there are notch band-pass and band-reject notch. In addition the book I'm studying (Digital Image Processing - Rafael C. Gonzalez) says that a notch filter is composed of the product of two high-pass filters. Just I don't understand how they work, how they are made and what they do.
The book also talks then about optimal notch filters that is used where there are several interference components in the image in the Fourier domain. Again I haven't understood how it works.
Could someone help me? Thank you very much!
So the difference between a notch filter and a band-pass is that I use the notch when I don't know what are the frequencies to pass (or delete) but I get it visually analyzing the image of the Fourier transform, right?