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How to I get a threshold value from looking at histogram

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Chok Chuan
Chok Chuan on 29 Mar 2015
Answered: Youssef Khmou on 29 Mar 2015
I need to get a threshold value not by looking at the graph I was told there is a way to calculate the threshold value from the histogram, Can someone help me

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Chok Chuan
Chok Chuan on 29 Mar 2015
I = imread('Test1.tif'); J=rgb2gray(I); figure; imhist(J);
thresholdValue = 100; bw = J > thresholdValue;
I am currently putting a casual 100 inside after looking at the histogram. I need the threshold value to segment the picture into fore and background. Is the a way to calculate a precise threshold value.

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Answers (1)

Youssef  Khmou
Youssef Khmou on 29 Mar 2015
Otsu's method exists as built in function with name graythresh, here is an example taken from Mathworks help page :
I = imread('coins.png');
level = graythresh(I);
BW = im2bw(I,level);
there might be other techniques to choose an adequate threshold.

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