역시 매트랩으로 했구요....코드는 아래와 같습니다.

a = imread('2108818074_06150699_IMG_0673.JPG');

b = uint8(zeros(size(a)));

b(:,:,1) = a(:,:,2);
b(:,:,2) = a(:,:,1);
b(:,:,3) = a(:,:,3);
imshow(b);

c = rgb2gray(a);

imshow(c);

d = uint8(abs(double(c) -255));

imshow(d);

e = uint8(zeros(size(a)));

e(:,:,1)    = a(:,:,1);
e(:,:,2)    = a(:,:,3);
e(:,:,3)    = a(:,:,2);

imshow(e);
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imwrite(b,'back_red.jpg','Quality', 100);
imwrite(c,'back_gray.jpg','Quality', 100);
imwrite(d,'back_inverse_gray.jpg', 'Quality', 100);
imwrite(e,'back_blue.jpg','Quality', 100);