aRGB2IND(RGB, nc)

function [X, map] = aRGB2IND(RGB, nc)
% Convert RGB image to indexed image
% More or less has the same syntax as rgb2ind 

if (nargin < 2)
	nc = 256;
end

m = size(RGB, 1);
n = size(RGB, 2);
X = zeros(m, n);
map(1,:) = RGB(1, 1, :)./nc;

for i = 1:m
    for j = 1:n
        RGBij = double(reshape(RGB(i,j,:), 1, 3)./nc);
        isNotFound = true;
        k = 0;
        while isNotFound && k < size(map, 1)
            k = k + 1;
            if map(k,:) ==  RGBij
                isNotFound = false;
            end
        end
        if isNotFound
            map = [map; RGBij];
        end
        X(i,j) = double(k);
    end
end
map = double(map);