Well, the following generates valid HTML (but not XHTML).

use constant MAX_COLS => 4;
use constant MAX_ROWS => 5;

my $col = 0;
my $row = 0;
print("<table>");
foreach my $image (@images) {
   print("<tr>") if !$col;
   print("<td>");

   print(...);

   if (++$col == MAX_COLS) {
      $col = 0;
      if (++$row == MAX_ROWS) {
         last;
      }
   }
}
print("</table>");
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Update: Bug fix. The conditions for printing <tr> and <td> were incorrect.