CODEWITHSUNDEEP
matlabimage-processing
3babala
3babala

Reputation: 11

Thresholding in MATLAB

How do I threshold an image to find the local maxima in a robust way?

I know I can just look at the data, visually guess at some appropriate h value, and do imextendedmax(I, h) where h is the threshold, but I'm looking for a more robust way to do it in MATLAB. I'm pretty new to MATLAB and coding so this is all foreign...

I'd need to do thresholding because of a noisy background (still somewhat noisy even after I filter it). imregionalmax() would therefore give way more local maximas than I need.

Upvotes: 1

Views: 2790

Answers (2)

Ninad Thakoor
Ninad Thakoor

Reputation: 23

See whether Otsu's method will do the job for you.Otsu's method

It's implemented as part of the Image processing toolbox."Matlab help for Otsu's Method"

level = graythresh(I)

Upvotes: 1

Paul R
Paul R

Reputation: 213120

Generate a histogram, find the max valued bin, then set your threshold at some fixed offset below this.

Or for a slightly more sophisticated approach, sum the histogram bin counts starting at the max value and work downwards until you have accumulated some fixed percentage of the total population, e.g. 0.1%, and set your threshold there.

Upvotes: 1

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