How to smooth plot of data?

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Steven 2014-1-18

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评论： Image Analyst 2014-1-19

Hi How can I smooth the following data? This is the gray intensity of an image. I could not use "smooth" function for that.

Is there any function for that or shall I use any filtering?

Thanks!

Steven

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Answer 1

Image Analyst 2014-1-18

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I can't tell what is signal and what is noise from that profile. Can you post the entire image? Like Jan said, it depends on what the image looks like. There are tons of filters you could use from simple linear filters like a moving box filter, to the non-linear median filter, to more complicated filters like Knn, sigma, to even more complicated (and better) filters like BM3D, K-SVD, K-LLD, non-local means, UINTA, ets.

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Steven 2014-1-19

Thanks so much!

How can I obtain the wavelength for such a plot?

Thanks!

Steven

Image Analyst 2014-1-19

It looks like there are two wavelengths, a high frequency one, and a lower frequency one that is the envelops. You can take the Fourier transform and look for spikes, which indicate a lot of energy at that wavelength.

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Answer 2

Jan 2014-1-18

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It depends on what the wanted result is. If you want to smooth the data extremely, use mean. A moving average filter is possible also, or a highpass filter, a Savitzki-Golay-filter or a mean over chunks of the data.