for loop is not iterating through images

I have a folder with a bunch of .png images. I then have a for loop where I want to read in all of .png images, store them in a variable, in this case y, perform a wavelet decomposition, extract the coefficients, then do some basic math to calculate the percentage of energy then finally add the calculated energy to a matrix. The problem is that the for loop is not iterating through the images in the folder, it gets stuck only reading in the first image then performing the calculations and storing the same number in the matrix. So I end up with the same number throughout my matrix. If anyone can help me fix this that would be greatly appreciated.

n = numel(flist); % find size of folder rund "flist = dir(fullfile(pwd, 'healthy', '*.png'));" outside of folder  first in command window. 'healthy' is name of the folder containg .png images
energy = zeros(n,1); %create empty matrix

for i = 1:(n)
    y = imread(sprintf('Layer_%d.png',n)); %read in file
    y2 = imresize(y, [256 256]);    %resize file
    [C,S] = wavedec2(y2,7,'db4');   %get wavelet coefficients
    [H4,V4,D4] = detcoef2('all',C,S,7); %reasigning horizontal, veritcal and diagonal coefficents 
    A4 = appcoef2(C,S,'db4',7); %reasigning approximation coefficients
    A4_abs = abs(A4); H4_abs = abs(H4); V4_abs = abs(V4); D4_abs = abs(D4); %absolute values
    A4_sq = A4_abs.^2; H4_sq = H4_abs.^2;V4_sq = V4_abs.^2; D4_sq = D4_abs.^2; %square values
    A4_sum = sum(A4_sq(:)); H4_sum = sum(H4_sq(:));  %sum all values & store new variable
    V4_sum = sum(V4_sq(:)); D4_sum = sum(D4_sq(:));  %sum all values & store new variable
    energy(i) = 100*(A4_sum/(H4_sum+V4_sum+D4_sum+A4_sum)); %calculate energy & store in matrix
end

Answer 1

[KSSV]

img = dir('*png') ; 
N = length(img) ;   % edited 
for i = 1:N
    I = imread(img(i).name)
    % do what you want
end

[madhan ravi]

length