#!/usr/bin/perl
use strict;

# I don't know enough matlab to do things like iterate over directories
# so this perl code does that for me and produces some static matlab code.

my %FLAGS;
$FLAGS{$_}=1 foreach (@ARGV);

print "A=[",join(' ',map { sprintf("reshape(im2double(imread('%s')),[],1)",$_) } <images/*.gif>),"];\n";

# Substract off mean face ... heh, like my advisor's face when he realizes
# I spent the weekend doing eigenfaces and studying linear algebra.
if ($FLAGS{'--subtract-mean'}) {
print <<_end_;
m=mean(A,2);
for i=1:size(A,2)
    A(:,i) = m-A(:,i);
end;
_end_
}

# Economy size svd
print <<_end_;
[U,S,V] = svd(A,0);
_end_

# Now, normalize U's between 0 & 1
print <<_end_;
for i=1:size(U,2)
    j      = U(:,i) - min(U(:,i));
    U(:,i) =   j    / max(j);
end;
_end_


# Generate eigenfaces
mkdir("faces") unless -d "faces";
print <<_end_;
sigmas = diag(S);
for i=1:10
    r  = randn(1,4);
    ef = sigmas(1)*r(1)*U(:,1) + sigmas(2)*r(2)*U(:,2) + sigmas(3)*r(3)*U(:,3) + sigmas(4)*r(4)*U(:,4);
    ef = ef - min(ef);
    ef = ef / max(ef);
    imwrite(reshape(ef,300,250),sprintf('faces/face%d.png',i),'png');
end;
_end_

# Export the columns of U as images, so I can look at them.
if ($FLAGS{'--dump-U'}) {
mkdir("U") unless -d "U";
print <<_end_;
for i=1:size(U,2)
    imwrite(reshape(U(:,i),300,250),sprintf('U/U%d.png',i),'png');
end;
_end_
}