I recently posted a question asking about the convergence behavior for a Mathematica algorithm Thinning https://dsp.stackexchange.com/questions/10667/what-does-convergence-mean-for-thinning, and I quickly recieved comments that the question was off-topic. It was then migrated to dsp.stackexchange.com.

All of this is fine, I'd just like to understand what happened? Right now I'm feeling like I committed some kind of faux pas.

The justification I have for asking the question is that, to my understanding, and I could be wrong, the function Thinning isn't something like FourierTransform. It's a specific image processing procedure that I've only seen in Mathematica, and I was inquiring about what a line meant on convergence for the function description.

1 Answer 1


Thinning is a morphological operation on images. It has certain well defined mathematical steps to it, which you can find in the wikipedia article (of course, reading up on more relevant literature/implementation details is left to you). It is by no means specific to Mathematica and an implementation can be found for most languages that have image processing packages/functions (python, MATLAB, C++, ...). Likewise, convergence is also not specific to Mathematica.

In short, your question had nothing to do with Mathematica, as was indicated by Sasha. I migrated your question to DSP Stack Exchange, which also handles theoretical and practical questions on image processing (which in fact, is their largest tag). There is no crime committed here — we migrate questions to other, more relevant sites in the Stack Exchange network in the hopes of helping you, the OP, to get a faster and better response (but no guarantee of actually getting a response).

If you do not want it migrated there, let me know and I'll work with the moderators there to cancel it. However, it will end up being closed as off-topic on this site.

  • ♦ I really appreciate your response. Right, of course I understand that "convergence" is not Mathematica specific, I just didn't know what it meant in the sense of reaching an end state for the Thinning process. My failure here was to not recognize how well defined Thinning was, so I apologize about that.
    – LCook
    Commented Sep 9, 2013 at 3:02
  • ♦ If you wouldn't mind, I'd rather cancel the question. My mistake.
    – LCook
    Commented Sep 9, 2013 at 3:15
  • @LCook No worries :) If you want to see the "convergence" in action, try this: With[{img = Import["https://i.sstatic.net/nWN75.png"]}, ListAnimate@FixedPointList[Thinning[#, 1] &, img]]
    – rm -rf Mod
    Commented Sep 9, 2013 at 3:17

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