hw2_01.m

function [x_std_dev] = hw2_01

    % generate 10 images of size 256x256 of pixel value 128
    x = ones(10,256,256)*128;

    % apply gaussian noise
    x = imnoise(x, 'gaussian', 0, 2.0);

    % calculate standard deviation
    x_std_dev = generate_std_dev(x);

end

%% function for finding the mean of all images
%  used in generate_std_dev function
function [outputMatrix] = matrix_mean(inputMatrix)
    number_of_images = length(inputMatrix);
    
    % memory allocation
    temp_matrix = zeros(size(inputMatrix(1)));
    
    % summation of all image values
    for i = 1:number_of_images
        temp_matrix = temp_matrix + inputMatrix(i);
    end
    
    % returns matrix where each pixel value is the mean of all the other
    % pixels at that index for all images
    outputMatrix = (1/number_of_images) * temp_matrix;
end

%% function for finding the stddev of all images
function [output_val] = generate_std_dev(input_matrix)

    number_of_images = length(input_matrix);
    
    % memory allocation
    temp_matrix = zeros(size(input_matrix(1)));
    
    % calls function to get avg matrix
    matrix_average = matrix_mean(input_matrix);
    
    % summation of all squared values
    for i = 1:number_of_images
        temp_matrix = temp_matrix + (matrix_average - input_matrix(i)).^2;
    end
    
    % divide temp
    temp_matrix = temp_matrix * (1/(number_of_images-1));
    
    % return sqrt value
    output_val = sqrt(temp_matrix);

end