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How to calculate the entropy of a grayscale image.

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Ishara Nipuni
Ishara Nipuni 2018-11-23
评论： Walter Roberson 2018-12-28
Hi can you help me to calculate the entropy of a grayscale image using Matlab? Here I've shown below the code that I tried. The code was working but I got the value of the entropy of my image as 'NaN'. So, please help me to find the entropy value of a grayscale image correctly.
I = imread('152.bmp');
x = entropy(I);
%functionH = MyEntropy(x);
imshow(x);
figure()
[Height,Width] = size(x);
[m,Binsx]=imhist(x);
m = m/(Height*Width);
sprintf('the sum of the histogram value is = %g',sum(m));
figure,plot(Binsx,m,'k')
xlabel('pixel value'),ylabel('relative count')
H = sum(-m.*log2(m));
sprintf('the entropy of the image is = %g',H)
  7 个评论
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Anurag ch
Anurag ch 2018-12-28
sir,can you give me the correct definition of normalization
Walter Roberson
Walter Roberson 2018-12-28
1. Statistics: Standardization of data obtained from different sources at different periods, through peer review or comparison against the objectives of data collection.
Source: http://www.businessdictionary.com/definition/normalization.html

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Miriam
Miriam 2018-11-23
Hi Ishara,
It looks like you are trying to find the height, width, and histogram using the entropy value you found. Maybe try:
[Height,Width] = size(I);
[m,Binsx] = imhist(I);
  3 个评论
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Miriam
Miriam 2018-11-25
I'm not sure I understand. The entropy of your image is a single number, what do you want to plot?
Image Analyst
Image Analyst 2018-11-25
There is an entropyfilt() that finds the entropy in a sliding window. Why do you think you want entropy anyway? What's the use case?

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