recolor an image
Contents
my rgb image
n = 0;
switch n
case 1
filename = 'Rosie_and_me.jpg';
case 2
filename = 'flowers4.png';
otherwise
filename = 'loomis.jpg';
end
rgb = imread(filename);
imshow(rgb);
256 colors
[X map] = rgb2ind(rgb,256);
imshow(X,map);
16 colors
[X2 map2] = rgb2ind(rgb,16);
imshow(X2,map2);
8 colors
[X3 map3] = rgb2ind(rgb,8,'nodither');
imshow(X3,map3);
look at colormap (very boring)
Xd=zeros(32,32*8);
for n=1:7
Xd(:,n*32+(1:32))=n;
end
Xd = int8(Xd);
imshow(Xd,map3);
look at chroma (very uncolorful)
x = map3*[1 -0.5 -0.5]';
y = map3*[0 1 -1]'*sqrt(3)/2;
z = map3*[1 1 1]'/3;
plot(x,y,'k.');
axis square
axis([-1 1 -1 1]);
grid;
pseudo-color
imshow(X3,jet(8));
try imapprox, no dithering
[Y, newmap] = imapprox(X,map,8,'nodither');
imshow(Y,newmap);
imapprox (with dithering)
[Y, newmap] = imapprox(X,map,8);
imshow(Y,newmap);
