function [zfilt] = bookfig4(z, threshold)
% Simple script to generate Figures 4 & 5, chapter 14 WITHOUT SPM! Just Matlab
% Book: Human Brain Function. Academic Press, 2nd edition, 2003
% Authors: Frackowiak, Friston, Frith, Dolan, Price, Zeki, Ashburner, and Penny.
% Script source: http://www.poirrier.be/~jean-etienne/presentations/rft/

% !!!!! YOU SHOULD HAVE RUN SCRIPTS bookfig1-3.m BEFORE THIS ONE
% !!!!!!!!!! IN ORDER TO HAVE THE CORRECT AND SAME 'z' MATRIX !

% How to run it? "z4 = bookfig4(z3, 0.93);"
% Argument 'a' is the square ramdom map from script bookfig1!

% Clear screen
clf;
close;

%FWHM = 10;
%sigma = FWHM/sqrt(8*log(2));
%z = normpdf(my2, 0, sigma);

for i = 1:100
    for j = 1:100
        if z(i,j) > threshold
            zfilt(i,j) = 1;
        else
            zfilt(i,j) = 0;
        end
    end
end

imagesc(zfilt);

% Beautify image
set(gca,'YDir','normal');
colormap('gray');
ylabel('Position du pixel en Y');
xlabel('Position du pixel en X');