jpegfrs.m

% JPEG error analysis and digital image forensic

% Load the original image
original_image = imread('original_image.jpg');

% Apply JPEG compression with quality factor 75
compressed_image = imresize(original_image, 0.5); % Resize the image to reduce its size
imwrite(compressed_image, 'compressed_image.jpg', 'Quality', 75);

% Load the compressed image
compressed_image = imread('compressed_image.jpg');

% Calculate the mean squared error (MSE) between the original and compressed images
MSE = immse(original_image, compressed_image);

% Display the MSE value
fprintf('MSE: %f\n', MSE);

% If the MSE value is higher than a threshold, the image may have been tampered with
if MSE > 100
    fprintf('The image may have been tampered with.\n');
else
    fprintf('The image is probably authentic.\n');
end

% Apply a digital forensic technique to detect traces of JPEG compression
DCT = dct2(compressed_image); % Calculate the 2D discrete cosine transform (DCT)
abs_DCT = abs(DCT); % Take the absolute value of the DCT coefficients
mean_DCT = mean(abs_DCT(:)); % Calculate the mean of the absolute DCT coefficients

% Display the mean value
fprintf('Mean DCT value: %f\n', mean_DCT);

% If the mean DCT value is higher than a threshold, the image may have been compressed with JPEG
if mean_DCT > 10
    fprintf('The image was probably compressed with JPEG.\n');
else
    fprintf('The image was probably not compressed with JPEG.\n');
end