It seems that much of the ringing is due to strong components in the middle of the frequency range caused by image border discontinuities.
I would like smooth this transition by rolling the image 50% and blurring say 5% strip now at the centre of the image (first X , then Y).
This would degrade that part of the image but it gets pretty much blown out by ringing anyway if there are significant differences between LH and RH borders as is often the case.
I have not been able to see how to blur just the middle strip.
Suggestions , please.
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