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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
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