Now we are talking past each other ;) You're right, of course, which is why I said I'm not sure FT would be useful in this case. I was giving the grandparent th

Now we are talking past each other ;) You're right, of course, which is why I said I'm not sure FT would be useful in this case. I was giving the grandparent the benefit of the doubt, however: it is at least conceivable to me that the evenly spaced discontinuities in the shredded image (due to the uniform slice width) could present as a frequency spike (or rather, a series of them) in the FT of some function of the input (the derivative, perhaps) in the same way that the FT of a Dirac comb is also a Dirac comb. Wild speculation, of course, because like I said - image processing is not my forte.