% Lecture 34: Images.
 
x = imread('h:easter-egg.jpg');
image(x)
axis off
nored = x;
nored(:,:,1) = zeros(size(x,1), size(x,2)); 
image(nored);
noblue = x;
noblue(:,:,3) = zeros(size(x,1), size(x,2));
image(noblue);
figure
image(x)

g = (x(:,:,1)+x(:,:,2)+x(:,:,3))/3;
??? Error using ==> +
Function '+' is not defined for values of class 'uint8'.

dx = double(x);
g = (dx(:,:,1)+dx(:,:,2)+dx(:,:,3))/3;
gx(:,:,1) = g;
gx(:,:,2) = g;
gx(:,:,3) = g;

% the array gx stores the grayscale image of x
image(uint8(gx))


% crypting the image

blur = randn(size(x,1));
key = inv(blur);
cd h:
bx = crypto(blur,dx);

image(uint8(bx))
xx = crypto(key,bx);
image(uint8(xx))
diary off