If an image is seen from afar, your perception is dominated by the low-frequency spatial frequencies of the image. At close range, high-frequency elements dominate. Here I tried to compose an image consisting of low-frequency 'welcome to STAR' and high-frequency 'welcome to PHENIX'. COuld not make it work. http://www.imagemagick.org/Usage/fourier/#blurring http://www.imagemagick.org/Usage/compose/#math Convert a sharp circle mask to a blurred circle mask (low-pass filter): convert circle_r14.png -blur 0x4 -auto-level gaussian_r14.png Do a FFT using this mask: convert lena.png -fft \ \( -clone 0 gaussian_r14.png -compose multiply -composite \) \ \( +clone -evaluate log 10000 -write lena_gblur_r14_spec.png +delete \) \ -swap 0 +delete -ift lena_gblur_r14.png