evaluate_PSNR_SSIM.m

% Multi-Stage Progressive Image Restoration
% Syed Waqas Zamir, Aditya Arora, Salman Khan, Munawar Hayat, Fahad Shahbaz Khan, Ming-Hsuan Yang, and Ling Shao
% https://arxiv.org/abs/2102.02808

close all;clear all;

datasets = {'Test100', 'Rain100H', 'Rain100L', 'Test2800', 'Test1200'};
num_set = length(datasets);

psnr_alldatasets = 0;
ssim_alldatasets = 0;

tic

for idx_set = 1:num_set
    file_path = strcat('/MATLAB Drive/painter/derain/derain_inference_epoch14_100/', datasets{idx_set}, '/');
    gt_path = strcat('/MATLAB Drive/painter/derain/test/', datasets{idx_set}, '/target/');
    path_list = [dir(strcat(file_path,'*.jpg')); dir(strcat(file_path,'*.png'))];
    gt_list = [dir(strcat(gt_path,'*.jpg')); dir(strcat(gt_path,'*.png'))];
    img_num = length(path_list);

    total_psnr = 0;
    total_ssim = 0;
    if img_num > 0 
        for j = 1:img_num
           image_name = path_list(j).name;
           gt_name = gt_list(j).name;
           input = imread(strcat(file_path,image_name));
           gt = imread(strcat(gt_path, gt_name));
           ssim_val = compute_ssim(input, gt);
           psnr_val = compute_psnr(input, gt);
           total_ssim = total_ssim + ssim_val;
           total_psnr = total_psnr + psnr_val;
       end
    end
    qm_psnr = total_psnr / img_num;
    qm_ssim = total_ssim / img_num;

    fprintf('For %s dataset PSNR: %f SSIM: %f\n', datasets{idx_set}, qm_psnr, qm_ssim);

    psnr_alldatasets = psnr_alldatasets + qm_psnr;
    ssim_alldatasets = ssim_alldatasets + qm_ssim;
    
end

fprintf('For all datasets PSNR: %f SSIM: %f\n', psnr_alldatasets/num_set, ssim_alldatasets/num_set);

toc

function ssim_mean=compute_ssim(img1,img2)
    if size(img1, 3) == 3
        img1 = rgb2ycbcr(img1);
        img1 = img1(:, :, 1);
    end

    if size(img2, 3) == 3
        img2 = rgb2ycbcr(img2);
        img2 = img2(:, :, 1);
    end
    ssim_mean = SSIM_index(img1, img2);
end

function psnr=compute_psnr(img1,img2)
    if size(img1, 3) == 3
        img1 = rgb2ycbcr(img1);
        img1 = img1(:, :, 1);
    end

    if size(img2, 3) == 3
        img2 = rgb2ycbcr(img2);
        img2 = img2(:, :, 1);
    end

    imdff = double(img1) - double(img2);
    imdff = imdff(:);
    rmse = sqrt(mean(imdff.^2));
    psnr = 20*log10(255/rmse);

end

function [mssim, ssim_map] = SSIM_index(img1, img2, K, window, L)

if (nargin < 2 || nargin > 5)
   ssim_index = -Inf;
   ssim_map = -Inf;
   return;
end

if (size(img1) ~= size(img2))
   ssim_index = -Inf;
   ssim_map = -Inf;
   return;
end

[M N] = size(img1);

if (nargin == 2)
   if ((M < 11) || (N < 11))
	   ssim_index = -Inf;
	   ssim_map = -Inf;
      return
   end
   window = fspecial('gaussian', 11, 1.5);	%
   K(1) = 0.01;								      % default settings
   K(2) = 0.03;								      %
   L = 255;                                  %
end

if (nargin == 3)
   if ((M < 11) || (N < 11))
	   ssim_index = -Inf;
	   ssim_map = -Inf;
      return
   end
   window = fspecial('gaussian', 11, 1.5);
   L = 255;
   if (length(K) == 2)
      if (K(1) < 0 || K(2) < 0)
		   ssim_index = -Inf;
   		ssim_map = -Inf;
	   	return;
      end
   else
	   ssim_index = -Inf;
   	ssim_map = -Inf;
	   return;
   end
end

if (nargin == 4)
   [H W] = size(window);
   if ((H*W) < 4 || (H > M) || (W > N))
	   ssim_index = -Inf;
	   ssim_map = -Inf;
      return
   end
   L = 255;
   if (length(K) == 2)
      if (K(1) < 0 || K(2) < 0)
		   ssim_index = -Inf;
   		ssim_map = -Inf;
	   	return;
      end
   else
	   ssim_index = -Inf;
   	ssim_map = -Inf;
	   return;
   end
end

if (nargin == 5)
   [H W] = size(window);
   if ((H*W) < 4 || (H > M) || (W > N))
	   ssim_index = -Inf;
	   ssim_map = -Inf;
      return
   end
   if (length(K) == 2)
      if (K(1) < 0 || K(2) < 0)
		   ssim_index = -Inf;
   		ssim_map = -Inf;
	   	return;
      end
   else
	   ssim_index = -Inf;
   	ssim_map = -Inf;
	   return;
   end
end

C1 = (K(1)*L)^2;
C2 = (K(2)*L)^2;
window = window/sum(sum(window));
img1 = double(img1);
img2 = double(img2);

mu1   = filter2(window, img1, 'valid');
mu2   = filter2(window, img2, 'valid');
mu1_sq = mu1.*mu1;
mu2_sq = mu2.*mu2;
mu1_mu2 = mu1.*mu2;
sigma1_sq = filter2(window, img1.*img1, 'valid') - mu1_sq;
sigma2_sq = filter2(window, img2.*img2, 'valid') - mu2_sq;
sigma12 = filter2(window, img1.*img2, 'valid') - mu1_mu2;

if (C1 > 0 & C2 > 0)
   ssim_map = ((2*mu1_mu2 + C1).*(2*sigma12 + C2))./((mu1_sq + mu2_sq + C1).*(sigma1_sq + sigma2_sq + C2));
else
   numerator1 = 2*mu1_mu2 + C1;
   numerator2 = 2*sigma12 + C2;
   denominator1 = mu1_sq + mu2_sq + C1;
   denominator2 = sigma1_sq + sigma2_sq + C2;
   ssim_map = ones(size(mu1));
   index = (denominator1.*denominator2 > 0);
   ssim_map(index) = (numerator1(index).*numerator2(index))./(denominator1(index).*denominator2(index));
   index = (denominator1 ~= 0) & (denominator2 == 0);
   ssim_map(index) = numerator1(index)./denominator1(index);
end

mssim = mean2(ssim_map);

end