MATLAB: How to find the exact index(row, col) of a maximum value in a matrix

indexing

I want to find the maximum value in an image, I tried to find its index and I found it after converting the image matrix into a vector. How can I find this value in a matrix? and then plot it over an image?

Best Answer

Let I be your image.

[m,n,p]  = size(I) ; 
x = 1:n ;
y = 1:m ;
[X,Y] = meshgrid(x,y) ; 
[val,idx] = max(I(:)) ; 
imshow(I)
hold on
plot(X(idx),Y(idx),'*r')

Related Solutions

MATLAB: How to find corresponding x values for array of y values

Use the following syntax

[M,I] = min(___)

When you are taking the min of an mxn array, I is a vector containnig the row numbers of the minimum values. Use that to index into your column of X values.

x = [3;10];
[MN,I] = min(rand(2,3))
MN = 1×3
    0.2223    0.2202    0.8156
I = 1×3
     2     1     2
x(I)
ans = 3×1
    10
     3
    10

MATLAB: Finding the indices of the maximum of a matrix for plotting

load('x.mat')
load('y.mat')
load('m.mat')
[X,Y] = meshgrid(x,y) ; 
Z = m ; 
% Make Z equal to size of X, Y
Z(1,:) = []; 
Z(:,1) = [] ;
% get max value 
[val,idx] = max(Z(:)) ; 
% plot
pcolor(x,y,Z)
shading interp 
colorbar
hold on
plot(X(idx),Y(idx),'*r')

Best Answer

Related Solutions

MATLAB: How to find corresponding x values for array of y values

MATLAB: Finding the indices of the maximum of a matrix for plotting

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