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If the ripple frequency is constant, but the effect is displaced from frame to frame, then fft filtering can work.
Attached is a mars image from a few years ago.
'Original mars' is the frame as stacked & processed.
'Noisy mars' is the same frame with a fixed pattern noise applied to simulate your problem
'fft noisy mars' is the frequency map (real component) of the noisy image. You can clearly see the frequencies where the pattern resides (hot spots).
'masked fft frequencies' is the same map with the offending frequencies masked.
'fft filtered' is the inverse fft of the frequency map showing the reconstructed image with the masked frequencies. Its not perfect, but it is a big improvement on the 'noisy' image. With a little care in the masking applied, a better result can easily be obtained.
It is fairly close to the original, pre-noise image.
All processing done in IRIS.
cheers
Maurice
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