function [] = jpeg_codec()
    A = imread('C:\Users\lab\Desktop\exercise_5\Lena_gray_8.tif');
    B = double(A);

    B = B-128;

    %quantization
    Bdct = blkproc(B, [8, 8], 'dct2');
    Bquant = blkproc(Bdct, [8, 8], 'quantization');
    zeros = nnz(Bquant);

    %dequantization
    Bdequant = blkproc(Bquant, [8, 8], 'dequantization');
    Bidct = blkproc(Bdequant, [8, 8], 'idct2');

    Bres = Bidct + 128;
    Bres = Bres/255;

    Bres = im2uint8(Bres);

    subplot(1,2,1);
    imshow(A);
    title('original');

    subplot(1,2,2);
    imshow(Bres);
    title('reconstructed');

    perc = zeros / (size(Bquant, 1)*size(Bquant, 2)) * 100;
    fprintf('percentage of zeros in the array is: %f %%', perc);

    [mse psnr] = mse_error(A, Bres);

        x = [1:1:10];

    mse = [33.0081, 56.1949, 75.0029, 92.5555, 110.2101, 128.9915, 147.4825, 164.9354, 184.2403, 200.5774];

    psnr = [32.9446, 30.6338, 29.3800, 28.4668, 27.7086, 27.0252, 26.4434, 25.9577, 25.4770, 25.1080];

    figure
    plot(x, mse, x, psnr);
    xlabel('alpha value');
    ylabel('msn, psnr errors');
end