The human brain figured out how to focus on visually salient objects a long time ago. The natural world in which we live has some statistical regularities that make it uniquely natural, as opposed to a chessboard pattern or a random company logo. Probably, the most commonly known statistical regularity is the 1/f law. It states that the amplitude of the ensemble of natural images obeys a 1/f distribution (as shown in the following screenshot). This is sometimes also referred to as scale invariance.
A one-dimensional power spectrum (as a function of frequency) of a two-dimensional image can be visualized with the following plot_power_spectrum function. We can use a similar recipe as for the magnitude ...
