How do I determine the percentage of pixels of a certain colour range within an area in my image?

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Jayden Hasemann 2017-9-10

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评论： Jayden Hasemann 2017-9-28

I am trying to determine the percentage of pixels of a certain colour range within an area in my image.

I have already turned the image to HSI to to then find a range of intensity in which the clouds would appear as. I now want to find out what percentage of cloud (range of intensity) is within a certain region i.e. around the sun.

This in order to then use this information in an if statement to determine if a white is present within a specified region of the image.

Any help would be appreciated.

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Matt J 2017-9-10

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编辑：Matt J 2017-9-10

在 MATLAB Online 中打开

 intensity = HSIimage(:,:,3);
 map= (intensity>=lowerlimit & intensity<=upperlimit);
 percentage=sum(map(:))/numel(map)*100;

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Matt J 2017-9-28

编辑：Matt J 2017-9-28

在 MATLAB Online 中打开

map2= all(map,2);
percentage=sum(map2,1)/numel(map2)*100

where map is as before.

Jayden Hasemann 2017-9-28

perfect Matt, thanks a heap

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Image Analyst 2017-9-11

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I don't think your algorithm is very robust. I suggest you follow the papers of researchers who have successfully found clouds and published their algorithms. See articles on cloud detection in Vision Bib:

http://www.visionbib.com/bibliography/motion-f716.html#Tracking%20for%20Weather,%20Clouds

16.6.2.12 Tracking for Weather, Clouds

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Jayden Hasemann 2017-9-11

Thanks for that, I see you have a very in depth knowledge in DSP with matlab. do you have any examples of finding clusters of a certain range of intensities within an image?