what is code for non-maxima suppression of a grey image
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Edge detection using wavelet transform need local maxima to find new approximation coefficient from detail coefficient.
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Sajid Khan
2013-10-10
Hi, attached is the source code for non maximal suppression. I also have submitted the code in file exchange but it will take some time for approval. I got help from canny edge detection code given in image processing toolbox
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S. Sal
2016-11-24
编辑:S. Sal
2016-11-24
Hello Sajid Khan, I am getting this error while using nonMaximalSupp.m you shared, The error is as follows: ___________________________________________________________
Undefined function 'cannyFindLocalMaxima' for input arguments of type 'double'.
Error in nonMaximalSupp (line 19) idxLocalMax = cannyFindLocalMaxima(dir,dx,dy,magGrad); _________________________________________________
Can you refine it please ? Thanks
Swank Williams
2023-7-1
编辑:Swank Williams
2023-7-1
Hi @S. Sal, for the function cannyFindLocalMaxima, you may have a try on the following codes. And you can find more details in the link https://www.cnblogs.com/mender/p/3501929.html
function idxLocalMax = cannyFindLocalMaxima(direction,ix,iy,mag)
[m,n] = size(mag);
switch direction
case 1
idx = find((iy<=0 & ix>-iy) | (iy>=0 & ix<-iy));
case 2
idx = find((ix>0 & -iy>=ix) | (ix<0 & -iy<=ix));
case 3
idx = find((ix<=0 & ix>iy) | (ix>=0 & ix<iy));
case 4
idx = find((iy<0 & ix<=iy) | (iy>0 & ix>=iy));
end
if ~isempty(idx)
v = mod(idx,m);
extIdx = (v==1 | v==0 | idx<=m | (idx>(n-1)*m));
idx(extIdx) = [];
end
ixv = ix(idx);
iyv = iy(idx);
gradmag = mag(idx);
switch direction
case 1
d = abs(iyv./ixv);
gradmag1 = mag(idx+m).*(1-d) + mag(idx+m-1).*d;
gradmag2 = mag(idx-m).*(1-d) + mag(idx-m+1).*d;
case 2
d = abs(ixv./iyv);
gradmag1 = mag(idx-1).*(1-d) + mag(idx+m-1).*d;
gradmag2 = mag(idx+1).*(1-d) + mag(idx-m+1).*d;
case 3
d = abs(ixv./iyv);
gradmag1 = mag(idx-1).*(1-d) + mag(idx-m-1).*d;
gradmag2 = mag(idx+1).*(1-d) + mag(idx+m+1).*d;
case 4
d = abs(iyv./ixv);
gradmag1 = mag(idx-m).*(1-d) + mag(idx-m-1).*d;
gradmag2 = mag(idx+m).*(1-d) + mag(idx+m+1).*d;
end
idxLocalMax = idx(gradmag>=gradmag1 & gradmag>=gradmag2);
Image Analyst
2013-3-24
Sounds like you have a paper in mind. Did you ask the authors if they have code to share with you, or search the File Exchange? I don't have the wavelet toolbox so I can't help you.
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