Amplitude swapping

A demonstration of the importance of phase information in images. Given two imagesswapphase() takes their Fourier transforms and constructs two new, synthetic, images formed from the swapped phase and amplitude imformation. In general it is the phase information that dominates. However, for textures where the amplitude spectra can be concentrated in a limited set of locations, the reverse can apply.

See Oppenheim and Lim's paper "The importance of phase in signals". Proceedings of the IEEE. Volume: 69 , Issue: 5 , May 1981

using TestImages
using Images
using ImagePhaseCongruency

img1 = centered(Float64.(Gray.(restrict(testimage("lighthouse")))))[-127:128, -127:128]
img2 = restrict(Float64.(testimage("mandril_gray")))[1:256, 1:256]

(newimg1, newimg2) = swapphase(img1, img2)

mosaic(Gray.(img1), newimg1, img2, newimg2; nrow=2)

Bottom 1) left: phase of lighthouse, amplitude of Mandrill 2) right: amplitude of lighthouse, phase of Mandrill

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