function [result] = sc_4_1()
  pic = imread('img.jpg');
  subplot(3, 2, 1);
  imshow(pic)
  [pic2, pic3, pic4, pic5] = work(pic);
  subplot(3, 2, 2);
  imshow(pic2)
  subplot(3, 2, 3);
  imshow(pic3)
  subplot(3, 2, 4);
  imshow(pic4)
  subplot(3, 2, 5);
  imshow(pic5)
  imwrite(pic2, 'imgout.jpg');
endfunction

function [pic2, pic3, pic4, pic5] = work(pic)
  pic2 = pic;
  pic3 = pic;
  pic4 = pic;
  pic5 = pic;
  for i = 1:size(pic)(1)
    for j = 1:size(pic)(2)
      # просто инверсия цветов
      pic2(i, j, 1) = 255 - pic2(i, j, 1);
      pic2(i, j, 2) = 255 - pic2(i, j, 2);
      pic2(i, j, 3) = 255 - pic2(i, j, 3);

      #уменьшение яроксти
      pic3(i, j, 1) = pic3(i, j, 1) / 2;
      pic3(i, j, 2) = pic3(i, j, 2) / 2;
      pic3(i, j, 3) = pic3(i, j, 3) / 2;

      #просто поменяем каналы
      pic4(i, j, 1) = pic4(i, j, 2);
      pic4(i, j, 3) = 0; #а синий канал просто выключим

      #увеличим контраст
      pic5(i, j, 1) = min(255, pic5(i, j, 1) + 50);
      pic5(i, j, 2) = min(255, pic5(i, j, 2) + 50);
      pic5(i, j, 3) = min(255, pic5(i, j, 3) + 50);
    endfor
  endfor
endfunction