Asked by Mona Mahboob Kanafi
on 21 May 2015

I'm trying to smooth a sharpe corner of a graph similar to what I've shown in the image below:

Can anyone give me some ideas how to handle this case? Should I use specific filters? interpolation techniques? etc,...

If it helps, my original case is 2D and for simplification I've drawn a 1D case above. Thanks

Answer by Adam
on 21 May 2015

Accepted Answer

Something like a mean smoothing filter should do the job if you convolve it with your graph function.

You can specify to only do so at the sample within a certain distance of a corner assuming you can identify the corner location.

Answer by Thomas Koelen
on 22 May 2015

Edited by Thomas Koelen
on 22 May 2015

Maybe construct splines?

example:

x=1:10;

y=rand(1,10);

cs = csapi(x,y);

fnplt(cs,2);

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Answer by Image Analyst
on 22 May 2015

One way is to use conv() to smooth/blur the signal:

windowWidth = 9; % Some odd number.

kernel = ones(1, windowWidth) / windowWidth;

smoothedSignal = conv(signal, kernel, 'same');

That is basically fitting the output element to the mean of elements in the sliding window. If you want it to follow the signal less closely, you can use a wider window.

Or you can use a Savitzky-Golay filter, done by sgolayfilt() in the Signal Processing Toolbox. I'm attaching a demo for you Mona. This is similar to conv() in that it does a fit in a sliding window, but you can specify some order of polynomial to fit to data in the window. For example, you can fit a quadratic or cubic function to the data in the window and assign the middle element to the fitted value. So with this filter, it's still a local filter but you have more control over how much you want to smooth or follow the original signal.

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Answer by Mona Mahboob Kanafi
on 25 May 2015

shmng
on 21 Dec 2016

Hallo Mona, Could you please share the command to achieve this. I am not able to reteive as per your solution. How can we edit 2D settings in cftool. I am also looking for similar solution to smoothen the curve at sharp edges.

Any help shall be thankful.

Regards, Shwetha

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