maximum pixel intensity of image

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Lalit Patil
Lalit Patil on 2 Oct 2012
Edited: Matt J on 10 Oct 2018
My current project is based on CCD and LASER. i want to calculate maximum intensity of laser strip on ccd.. so please give me a code to find maximum intensity pixel and location of that pixel as row and column..

Accepted Answer

Image Analyst
Image Analyst on 2 Oct 2012
Try this:
% Generate sample data
imageArray = [ 3 4 5 5 4 4 5 5 3; 5 4 5 5 3 3 3 3 4];
% Find the max value.
maxValue = max(imageArray(:))
% Find all locations where it exists.
[rowsOfMaxes colsOfMaxes] = find(imageArray == maxValue)
That said, this is probably not what you want to do to find the laser spot. You probably want to either do a spatial filter or a threshold, and then binarize and find the centroid of the binary blob. There are some laser tracking programs in the File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/32492-laser-dot-isolation, http://www.mathworks.com/matlabcentral/fileexchange/33666-simple-particle-filter-demo, http://www.mathworks.com/matlabcentral/fileexchange/17960-particle-filter-color-tracker, http://www.mathworks.com/matlabcentral/fileexchange/31463-simple-demo-program-for-color-based-tracking, etc. etc.

More Answers (4)

Matt J
Matt J on 2 Oct 2012
[maxval,idx]=max(image(:));
[row,col]=ind2sub(size(image), idx);

Lalit Patil
Lalit Patil on 2 Oct 2012
This gives one irritating figure and gives only value of one pixel... The response of this code is same for all figures.. ... and in my image there is more than one pixel that contains same maximum intensity... So, please give modification or anothe code...

Lalit Patil
Lalit Patil on 3 Oct 2012
Thank you Image Analyst... This thing works me... Now I want to generate Image array from image in terms of row and column as you have shown.. I tried imread but it gives M*N*3 array... and i require only M*N array.. So please give code or suggestion..
  5 Comments
Nonu 007
Nonu 007 on 1 Nov 2015
Hello Image Analyst. I am trying that too but I am not getting a single line of cross section in 2D at highest Peak. Here i am attaching a fig. May be from that you can help me.
I want a cross section line like this from the image at max intensity.

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Shel
Shel on 10 Oct 2018
Hi, I am using max(I(:)) on my image but the error "Index exceeds matrix dimensions. " shows up ... do you know what the problem is?
  1 Comment
Matt J
Matt J on 10 Oct 2018
You've probably created a variable named 'max' previously in your workspace, which Matlab is trying to index.

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