my @files = glob("*.jpg");
my $width = 3;

my @images = ();

for my $i (0..$#files) {
  if ($i % $width == 0) { # new row, append to dimension X
    push (@images, { schleifeY => [ { inhalt => $files[$i] } ] } );
  }
  else { # new column, append to dimension Y
    push (@{ $images[-1]->{schleifeY} }, { inhalt => $files[$i] } );
  } # else
} # for

$template->param(schleifeX => \@images);