Identification of Earthquake Induced Damage Areas - Earth Science: New Methods and Studies - page 118

The low frequencies are plotted near the origin (center) while the higher frequen-
cies are plotted further out. Generally, the majority of the information in an image is in
the low frequencies indicated by the bright areas at the center of the Figures 4c and d.
Figure 4. (a) Original pre-earthquake data, (b) original post-earthquake data, (c) FFT pre-earthquake
image, (d) FFT post-earthquake image, (e) IFFT pre-earthquake image, (f) IFFT post-earthquake image.