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Possible to apply filter2 to only values above a limit?

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Josh
Josh on 27 Feb 2014
Commented: Josh on 6 Mar 2014
I have an array which I'm attempting to filter with a Gaussian blur to smooth the surface and contour plots. Without any filtering, this is the resulting contour plot:
This code:
load 'A'
G=fspecial('gaussian',[5 5],2);
Af=filter2(G,A,'same');
contour(X,Y,A);
Gives the following contour plot:
As you can see, the contours are nicely smoothed, but the filter has blurred the transitions too much and shifted them wider and outwards.
My Question:
Is it possible to refer to just array elements above a certain value for the filtering?
I'm sure it must be and I'm just being stupid not figuring it out.
Cheers

Accepted Answer

Oliver Woodford
Oliver Woodford on 3 Mar 2014
Compute the filtered version for all pixels, and simply replace the pixels above a certain value with their filtered value:
G = fspecial('gaussian',[5 5],2);
Af = filter2(G,A,'same');
M = A > thresh;
A(M) = Af(M);
contour(X,Y,A);

More Answers (1)

Josh
Josh on 2 Mar 2014
bump
Perhaps there's a different type of filter I can use, which preserves edges better?

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