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Diffstat (limited to 'macros/localMaximaFinder.sci')
| -rw-r--r-- | macros/localMaximaFinder.sci | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/macros/localMaximaFinder.sci b/macros/localMaximaFinder.sci new file mode 100644 index 0000000..45e0806 --- /dev/null +++ b/macros/localMaximaFinder.sci @@ -0,0 +1,118 @@ +function [location]=localMaximaFinder(inputMatrix,neighborhood,maxNoOfMaxima,threshold) +// Returns local maxima in input matrices +// +// Calling Sequence +// location=localMaximaFinder(inputMatrix,neighborhood,maxNoOfMaxima,threshold) +// +// Parameters +// inputMatrix: 2-D input matrix +// neighborhood: It specifies the neighborhood around maxima, function zeros out the values inside the block. Neighborhood is a two element vector,first one indicates number of rows in neighborhood,second one indicates columns, of odd intergers. +// maxNoOfMaxima: maximum number of local maxima you want to find. +// threshold: It specifies minimum value of the local maxima. +// +// Description +// localMaximaFinder returns the M-by-2 matrix where M is the number of local maxima and each row represents one local maximum +// +// Examples +// I=imread("lena.jpeg"); +// grayImage=rgb2gray(I); +// location=localMaximaFinder(grayImage); +// mat=[1 6 3;4 8 2;9 7 5]; +// loc=localMaximaFinder(mat,[1 3],4,3); + + [lhs,rhs]=argn(0) + if rhs<4 then + error(msprintf(" Not enough input arguments")) + elseif rhs>4 then + error(msprintf(" Too many input arguments to the function")) + elseif lhs>1 then + error(msprintf(" Too many output arguments")) + end + + [iRows iCols]=size(inputMatrix) + [nRows nCols]=size(neighborhood) + if ~isreal(inputMatrix) | ~isreal(neighborhood) + error(msprintf(" Wrong input argument,complex matrix is not expected")) + elseif ~nRows==1 | ~nCols==2 + error(msprintf("Neighborhood property must be a vector with 2 columns")) + end + + nh_x=neighborhood(1,1); + nh_y=neighborhood(1,2); + if modulo(nh_x,2)==0 | modulo(nh_y,2)==0 + error(msprintf("-Neighborhood property must be odd")) + elseif ~nh_x<=iRows | ~nh_y<=iCols + error(msprintf("Each dimension of the NeighborhoodSize property value must be less than or equal to the corresponding dimension of the input matrix")) + end + + nh_x=floor(nh_x/2); + nh_y=floor(nh_y/2); + count=0; + index=1; + k=1; + while count<maxNoOfMaxima + max_data=-1; + //to find maximum in the input matrix + for i=1:iRows + for j=1:iCols + if inputMatrix(i,j)>max_data + max_data=inputMatrix(i,j); + max_xIn=i; + max_yIn=j; + end + end + end + if threshold<=max_data + location(k,1)=max_yIn; + location(k,2)=max_xIn; + k=k+1; + + //to zero-out the values around the neighborhood + if max_xIn-nh_x<1 then + start_x=1 + else + start_x=max_xIn-nh_x + end + if max_yIn-nh_y<1 then + start_y=1 + else + start_y=max_yIn-nh_y + end + if max_xIn+nh_x>iRows then + end_x=iRows + else + end_x=max_xIn+nh_x + end + if max_yIn+nh_y>iCols then + end_y=iCols + else + end_y=max_yIn+nh_y + end + for i=start_x:end_x + for j=start_y:end_y + inputMatrix(i,j)=0; + end + end + //to check the existence of non-zero element + nonZeroCount=0; + for i=1:iRows + for j=1:iCols + if ~inputMatrix(i,j)==0 then + nonZeroCount=nonZeroCount+1; + break; + end + end + if nonZeroCount==1 then + break; + end + end + if nonZeroCount==0 then + break; + end + count=count+1; + + else + break; //if maximum number in input matrix is less than threshold + end + end +endfunction |