How to reverse frequency spectrum of a 2D image?

1. What is frequency spectrum of an image?
2. How do you draw a frequency spectrum of a signal?

What is frequency spectrum of an image?

Frequency spectrum of a 2D image is a discrete Fourier transform of the image performed to obtain decomposition of the signal into different frequency bands.

How do you draw a frequency spectrum of a signal?

Frequency spectrum of a signal is the range of frequencies contained by a signal. For example, a square wave is shown in Fig. 3.5A. It can be represented by a series of sine waves, S(t) = 4A/π sin(2πft) + 4A/3π sin(2π(3f)t) + 4A/5π sin(2π(5f)t + …)