correct.m

input_path = 'img.jpg';
save_path = 'img_processed.jpg';

img = imread(input_path);
if size(img,3)==3
   img = rgb2gray(img);
end

movingPoints = [19 103; 2353 337; 2391 1640;32 1925]; %coordinate of distorted corners
fixedPoints=[0 0;2500 0;2500 1500;0 1500]; %coordinate of image's corners
TFORM = fitgeotrans(movingPoints,fixedPoints,'projective');
R=imref2d(size(img),[1 size(img,2)],[1 size(img,1)]);
imgTransformed=imwarp(imread(input_path),TFORM,'OutputView',R);
imgTransformed = imgTransformed(1:1500, 1:2500, :);
figure, imshow(imgTransformed);
imwrite(imgTransformed, save_path)
'Done'