Effect of repeated JPEG compression on image quality and content

increasing_compression.m

% Load the 'original image', rescale to 1920 width, crop to 1080 height
originalImage = imread('YOURPHOTOHERE.JPG');
scaledImage = imresize(originalImage, [NaN 1920]);
scaledImage = imcrop(scaledImage,[0, size(scaledImage,1)/2-1080/2,...
                                  size(scaledImage,2), size(scaledImage,1)/2+1080/2-1]);
 
% Create a data output folder
[currentPath, ~, ~]= fileparts(mfilename('fullpath'));
mkdir(fullfile(currentPath,'data'))                                 %   Create the data directory
 
% Preallocate the filesize array
filesizes = zeros([101,1]);
 
for q = 100:-1:0
    % Save the compressed image
    filename = sprintf('frame%03d.jpg',100-q);
    filepath = fullfile(currentPath,'data',filename);
    imwrite(scaledImage,filepath,'Quality',q);
     
    s = dir(filepath);
    filesizes(100-q+1) = s.bytes;
    figure(1)
    plot(1:101,filesizes,'LineWidth',5);
    text(20,2*max(filesizes)/3,sprintf('Image Quality: %03d\nSize: %u bytes',q,filesizes(100-q+1)),...
     'FontSize',36)
    xlim([1,101])
    plotImage = getframe;
     
    % Load the compressed image and overlay a plot of the filesizes
    compressedImage = imread(filepath);
    fusedImage = imfuse(compressedImage,plotImage.cdata,'blend');
     
    imwrite(fusedImage,filepath,'Quality',100);
end
 
filename = 'decreasingimagequality.avi';
filepath = fullfile(currentPath,'data',filename);
writerObj = VideoWriter(filepath);
writerObj.FrameRate = 10;
open(writerObj);
for i = 0:100
    filename = sprintf('frame%03d.jpg',i);
    filepath = fullfile(currentPath,'data',filename);
    frame = im2frame(imread(filepath));
    writeVideo(writerObj,frame);
end
close(writerObj);

repeated_compression.m

% Load the 'original image', rescale to 1920 width, crop to 1080 height
originalImage = imread('YOURPHOTOHERE.JPG');
scaledImage = imresize(originalImage, [NaN 1920]);
scaledImage = imcrop(scaledImage,[0, size(scaledImage,1)/2-1080/2,...
                                  size(scaledImage,2), size(scaledImage,1)/2+1080/2-1]);
 
% Create a data output folder
[currentPath, ~, ~]= fileparts(mfilename('fullpath'));
mkdir(fullfile(currentPath,'data'))                                 %   Create the data directory
 
% Preallocate the filesize array
filesizes = zeros([101,1]);
 
% Save highest quality image
filename = 'frame000.jpg';
filepath = fullfile(currentPath,'data',filename);
imwrite(scaledImage,filepath,'Quality',100);
 
for q = 99:-1:0
    % Load previous compressed image
    filename = sprintf('frame%03d.jpg',100-q-1);
    filepath = fullfile(currentPath,'data',filename);
    scaledImage = imread(filepath);
    % Save the compressed image
    filename = sprintf('frame%03d.jpg',100-q);
    filepath = fullfile(currentPath,'data',filename);
    imwrite(scaledImage,filepath,'Quality',q);
end
 
filename = 'repeatedcompression.avi';
filepath = fullfile(currentPath,'data',filename);
writerObj = VideoWriter(filepath);
writerObj.FrameRate = 10;
open(writerObj);
for i = 0:100
    filename = sprintf('frame%03d.jpg',i);
    filepath = fullfile(currentPath,'data',filename);
    frame = im2frame(imread(filepath));
    writeVideo(writerObj,frame);
end
close(writerObj);

repeated_compression_10x.m

% Create a data output folder
[currentPath, ~, ~]= fileparts(mfilename('fullpath'));
mkdir(fullfile(currentPath,'data'))                                 %   Create the data directory
 
% Preallocate the filesize array
filesizes = zeros([101,1]);
 
% Save highest quality image
filename = 'frame000.jpg';
filepath = fullfile(currentPath,'data',filename);
imwrite(scaledImage,filepath,'Quality',100);
 
for q = 1:1000
    % Load previous compressed image
    filename = sprintf('frame%03d.jpg',q-1);
    filepath = fullfile(currentPath,'data',filename);
    scaledImage = imread(filepath);
    % Save the compressed image with random (0-25) quality
    filename = sprintf('frame%03d.jpg',q);
    filepath = fullfile(currentPath,'data',filename);
    imwrite(scaledImage,filepath,'Quality',mod(100-q,100));
end
 
filename = 'repeatedcompression10x.avi';
filepath = fullfile(currentPath,'data',filename);
writerObj = VideoWriter(filepath);
writerObj.FrameRate = 30;
open(writerObj);
for i = 0:1000
    filename = sprintf('frame%03d.jpg',i);
    filepath = fullfile(currentPath,'data',filename);
    frame = im2frame(imread(filepath));
    writeVideo(writerObj,frame);
end
close(writerObj);