How to smooth plot of data?

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

Answer 1

[Image Analyst]

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.

[Image Analyst]

Attached are demos for anistoropic diffusion and Savitzky-Golay if you're interested.

[Steven]

Thanks so much!

How can I obtain the wavelength for such a plot?

Thanks!

Steven

[Image Analyst]

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.

Answer 2

[Jan]

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.