global sum; % 全局变量sum，用来求所有8*8块的PSNR的均值
sum = 0.0;
Q = [16 11 10 16 24 40 51 61 % 量化矩阵Q
     12 12 14 19 26 58 60 55
     14 13 16 24 40 57 69 56
     14 17 22 29 51 87 80 62
     18 22 37 56 68 109 103 77
     24 35 55 64 81 104 113 92
     49 64 78 87 103 121 120 101
     72 92 95 98 112 100 103 99];
 
Cannon = [1 1 1 2 3 6 8 10 
          1 1 2 3 4 8 9 8 
          2 2 2 3 6 8 10 8 
          2 2 3 4 7 12 11 9 
          3 3 8 11 10 16 15 11 
          3 5 8 10 12 15 16 13 
          7 10 11 12 15 17 17 14 
          14 13 13 15 15 14 14 14];
 
Nikon = [2 1 1 2 3 5 6 7 
         1 1 2 2 3 7 7 7  
         2 2 2 3 5 7 8 7 
         2 2 3 3 6 10 10 7 
         2 3 4 7 8 13 12 9 
         3 4 7 8 10 12 14 11 
         6 8 9 10 12 15 14 12 
         9 11 11 12 13 12 12 12];

my_policy = [1 1 1 2 3 6 7 8
             1 1 2 3 5 7 9 8
             2 2 2 3 5 8 10 12
             2 2 3 4 6 9 12 12
             3 3 4 8 9 10 11 12
             4 4 5 8 10 12 13 14
             6 8 9 10 12 13 14 15
             9 11 12 13 14 15 16 17];
             

% 读入原始图片
img = imread('lena.bmp');

% 转化为灰度并输出
gray = rgb2gray(img);
imwrite(gray , 'gray-lena.bmp');
psnr_gray = im2double(gray);
%对函数进行图片分块，并对每块8*8的小块进行dct、量化、idct，计算PSNR值
I2 = blkproc(gray , [8 8] , @my_2dct , Q);
real_pic = mat2gray(I2); % 注意，最后要再次转化为灰度！刚开始没加，一直是错的！
disp('使用Q为量化矩阵，PSNR均值为：')
disp(sum / 4096);
imwrite(real_pic , 'Q.bmp');


% 对于Jpeg Standard Q，遍历系数a，计算PSNR并作图
x = [];
y = [];
count = 0;
for a = 0.1 : 0.1 : 2
    tempQ = a .* Q;
    sum = 0.0;
    Block8_D2_dct = gray;
    I2 = blkproc(Block8_D2_dct , [8 8] , @my_2dct , tempQ);
%    real_pic = mat2gray(I2);
%    imwrite(real_pic , ['Q_',num2str(a),'_idct.bmp']);
    ans = sum / 4096;
    count = count + 1;
    x(count) = a;
    y(count) = ans;
end
disp(y);
figure('NumberTitle', 'off', 'Name', 'Q为量化矩阵，PSNR-a曲线');
plot(x , y);

% 对于Canon IXUS 60 ，遍历系数a，计算PSNR并作图
x = [];
y = [];
count = 0;
for a = 0.1 : 0.1 : 2
    tempCannon = a .* Cannon;
    sum = 0.0;
    Block8_D2_dct = gray;
    I2 = blkproc(Block8_D2_dct , [8 8] , @my_2dct , tempCannon);
%    real_pic = mat2gray(I2);
%    imwrite(real_pic , ['Cannon_',num2str(a),'_idct.bmp']);
    ans = sum / 4096;
    count = count + 1;
    x(count) = a;
    y(count) = ans;
end
disp(y);
figure('NumberTitle', 'off', 'Name', 'Cannon为量化矩阵，PSNR-a曲线');
plot(x , y);

% 对于Nikon CoolPix L12 ，遍历系数a，计算PSNR并作图
x = [];
y = [];
count = 0;
for a = 0.1 : 0.1 : 2
    tempNikon = a .* Nikon;
    sum = 0.0;
    Block8_D2_dct = gray;
    I2 = blkproc(Block8_D2_dct , [8 8] , @my_2dct , tempNikon);
    %real_pic = mat2gray(I2);
    %imwrite(real_pic , ['Nikon_',num2str(a),'_idct.bmp']);
    ans = sum / 4096;
    count = count + 1;
    x(count) = a;
    y(count) = ans;
end
disp(y);
figure('NumberTitle', 'off', 'Name', 'Nikon为量化矩阵，PSNR-a曲线');
plot(x , y);

%对于自己设计的量化矩阵 ，遍历系数a，计算PSNR并作图
x = [];
y = [];
count = 0;
for a = 0.1 : 0.1 : 2
    tempmy = a .* my_policy;
    sum = 0.0;
    Block8_D2_dct = gray;
    I2 = blkproc(Block8_D2_dct , [8 8] , @my_2dct , tempmy);
    ans = sum / 4096;
    count = count + 1;
    x(count) = a;
    y(count) = ans;
end
disp(y);
figure('NumberTitle', 'off', 'Name', '自己实现的量化矩阵，PSNR-a曲线');
plot(x , y);

% 使用Cannon和Nikon处理自己的图片，并计算PSNR
img1 = imread('shoot.bmp');
gray1 = rgb2gray(img1);

gray2 = imread('boat.bmp');

gray3 = imread('barbara.bmp');

% 图片1：shoot.bmp
I2 = blkproc(gray1 , [8 8] , @my_2dct , Cannon);
real_pic = mat2gray(I2); % 注意，最后要再次转化为灰度！刚开始没加，一直是错的！
disp('图片1:shoot.bmp，使用Cannon为量化矩阵，PSNR均值为：')
disp(sum / 4096);
imwrite(real_pic , 'shoot_cannon.bmp');

I2 = blkproc(gray1 , [8 8] , @my_2dct , Nikon);
real_pic = mat2gray(I2); % 注意，最后要再次转化为灰度！刚开始没加，一直是错的！
disp('图片1:shoot.bmp，使用Nikon为量化矩阵，PSNR均值为：')
disp(sum / 4096);
imwrite(real_pic , 'shoot_Nikon.bmp');

% 图片2：boat.bmp
I2 = blkproc(gray2 , [8 8] , @my_2dct , Cannon);
real_pic = mat2gray(I2); % 注意，最后要再次转化为灰度！刚开始没加，一直是错的！
disp('图片2:boat.bmp，使用Cannon为量化矩阵，PSNR均值为：')
disp(sum / 4096);
imwrite(real_pic , 'boat_cannon.bmp');

I2 = blkproc(gray2 , [8 8] , @my_2dct , Nikon);
real_pic = mat2gray(I2); % 注意，最后要再次转化为灰度！刚开始没加，一直是错的！
disp('图片2:boat.bmp，使用Nikon为量化矩阵，PSNR均值为：')
disp(sum / 4096);
imwrite(real_pic , 'boat_Nikon.bmp');

% 图片3：barbara.bmp
I2 = blkproc(gray3 , [8 8] , @my_2dct , Cannon);
real_pic = mat2gray(I2); % 注意，最后要再次转化为灰度！刚开始没加，一直是错的！
disp('图片3:barbara.bmp，使用Cannon为量化矩阵，PSNR均值为：')
disp(sum / 4096);
imwrite(real_pic , 'barbara_cannon.bmp');

I2 = blkproc(gray3 , [8 8] , @my_2dct , Nikon);
real_pic = mat2gray(I2); % 注意，最后要再次转化为灰度！刚开始没加，一直是错的！
disp('图片3:barbara.bmp，使用Nikon为量化矩阵，PSNR均值为：')
disp(sum / 4096);
imwrite(real_pic , 'barbara_Nikon.bmp');