function heightthreshold(n)
% Simple script to generate random numbers and a threshold
% Script source: http://www.poirrier.be/~jean-etienne/presentations/rft/

% How to run it? Just type "heightthreshold(n)"
% with n = number of pixels on 1 side

% First part of the graph: random values
s = randn(n);
s = exp(s);

% Compute replacement of random values by the mean within each square
% It's not for smoothing things but big points are better seen
dim = 2; % square dimension --> can be modified for any other dimension
nsquare = n / dim; % number of squares in one dimension of image
sum = 0; % sum of values for each square
nv = 0; % number of values collected in each square

for i = 1:nsquare
    for j = 1:nsquare
        % traverse each square to collect random data
        for k = ((i - 1) * dim + 1):((i - 1) * dim + dim)
            for l = ((j - 1) * dim + 1):((j - 1) * dim + dim)
                % get data
                sum = sum + s(k, l);
                nv = nv + 1;
            end
        end
        mean = sum / nv;
        % traverse each square to put means data
        for k = ((i - 1) * dim + 1):((i - 1) * dim + dim)
            for l = ((j - 1) * dim + 1):((j - 1) * dim + dim)
                % put the mean
                s(k, l) = mean;
            end
        end
        % reset values
        sum = 0;
        nv = 0;
    end
end

% Display graph
surf(s);
hold on;

% Beautification of graph
title('Ensemble de valeurs aleatoires');
xlabel('Position du pixel en X');
ylabel('Position du pixel en Y');
zlabel('Valeur du pixel exprimee en Z');
colormap(cool);

pause;

% Second part of the graph: threshold at pct% of maximum value
pct = 70;
filter = max(max(s)) * (pct/100);

for i = 1:n
    for j = 1:n
        t(i,j) = filter;
    end
end
surf(t);

% Beautification of graph
title('Ensemble de valeurs aleatoires avec filtre');

hold off;