main.m

%Nioi Pier Giuliano
%Creating negative of a grayscale image [in the right way]
%Clean up all variables and close all existing windows
clear all
close all

% step 1
%load a grayscale image
I=imread('cameraman.tif');
%show images
subplot(4,2,1); imshow(I); title('original image');
subplot(4,2,2); imhist(I); title('hist of original image');

% step 2
%calling my function to create negative of I
N=negative(I);
%show images
subplot(4,2,3); imshow(N); title('negative image');
subplot(4,2,4); imhist(N); title('hist of negative image');

% step 3
%negative of negative, must be equeal to I
NN=negative(N);
if(NN==I)
    disp('NN IS equal to I');
else
    disp('NN IS NOT equal to I');
end


% step 4
%wrong negative function
WN=wrong_negative(I);
%show images
subplot(4,2,5); imshow(WN); title('wrong negative image');
subplot(4,2,6); imhist(WN); title('hist of wrong negative image');

% step 5
%wrong negative of wrong negative, should be equeal to I, but..
NWN=wrong_negative(WN);
if(NWN==I)
    disp('NWN IS equal to I');
else
    disp('NWN IS NOT equal to I');
end

% step 6
%using matlab IPT function for comparisons
N2=imcomplement(I);
if(N==N2)
    disp('N2 IS equal to N');
else
    disp('N2 IS NOT equal to N');
end
%show images
subplot(4,2,7); imshow(N2); title('matlab negative image');
subplot(4,2,8); imhist(N2); title('hist of matlab negative image');