From: The World In Your Head by Steven Lehar

Fig. 11.1 (A) Original image. (B) Fourier low-pass filtered version of the original, in which the higher harmonic frequencies are eliminated. (C) Fourier high-pass filtered version in which lower frequencies are eliminated. (D through F) Band-pass filtered versions of the original, at three different spatial frequency bands, showing how the irregular pattern of the input image is expressed in terms of patterns of periodicity in the imge. Note that the ringing artifacts observed in these images reflect the global Gestalt-like features of the image, such as the circular head centered in the square frame.