How do I warp a 1 dimensional signal in frequency domain?

1. Which operation is required to convert an image from spatial domain to frequency domain?
2. Why do we perform image processing in frequency domain although images are generally represented in the spatial domain?

Which operation is required to convert an image from spatial domain to frequency domain?

A Fast Fourier transformation is a tool of the frequency domain used to convert the spatial domain to the frequency domain. For smoothing an image, low filter is implemented and for sharpening an image, high pass filter is implemented.

Why do we perform image processing in frequency domain although images are generally represented in the spatial domain?

Answer- Many times, image processing tasks are best performed in a domain other than the spatial domain. Moreover, it is easy to detect some features in a particular domain,i.e., a new information can be obtained in other domains.