MEAN OF IMAGE IN MATLAB

format compact
%Firstly, I converted all the images in the vector form.
whereImagesReside = 'lfwdataset';
%dir function will return the images in a structure array.
listOfImages= dir(fullfile(whereImagesReside, '*.pgm'));
%0x1 structure array is created
data = cell(size(listOfImages));
%pmg files are stored in column matrix columnMatrix in the end of the loop
%below

for k=1:numel(listOfImages)
      data{k}=imread(fullfile(whereImagesReside, listOfImages(k).name));
      %data{k}=im2double(rgb2gray(data{k}));
      [r,c] = size(data{k}); % get number of rows and columns in image
      %columnMatrix(:,k)=data(:);
      V{k}=data(:);
end

%So, data cell array holds the intensity of each gray image.
%intensity = cellfun(@imshow, data, 'uniform', 0);
%disp(intensity);

How can I take the mean of image?

[Rik]

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Answer 1

[Rik]

If your list of images is a 0x1 struct, then the files are not found. Once you solve that issue, you can use the code below to find the intensity. Note that storing the full image may require a lot of memory, so you may consider skipping that.

data = cell(size(listOfImages));
intensity = zeros(size(listOfImages));
for k=1:numel(listOfImages)
    data{k}=imread(fullfile(whereImagesReside, listOfImages(k).name));
    intensity(k)=mean(data{k}(:));%mean will convert your data type to double
end