How can I give different thresholds to an image

How can I give different thresholds to an image? If 'cot' is the image matrix I have attached how can i give a threshold of zero, implying all pixels with non-zero values? Then all pixels above 1, and then all those above 5?

Answer 1

[Walter Roberson]

first_answer = cot ~= 0;
second_answer = cot > 1;
third_answer = cot > 5;

If you are trying to categorize the pixels by range, then see discretize()

[Joydeb Saha]

ncFiles = dir('E:\data\2002\*.nc');
N = length(ncFiles) ; 
Q = zeros(N,1) ; 
for i = 1:N
    ncFile = fullfile(ncFiles(i).folder,ncFiles(i).name) ; 
    data_Wwind=netcdf(ncFile); 
    cot=data_Wwind{'M2TMNXRAD_5_12_4_TAUHGH'}(:);
    th5 = cot > 3;
    B = double(th5);
    Q(i)=sum(B(:) == 1);
end

I have used this code to find the total number of pixels those are above threshold 3 for all the data files in the folder. How can I find the mean value of cot for all the data files (every month) only for the pixels those are above threshold three(3)?