print qq(<input type="image" name="sort:$field:asc" src="$image_dir/down.png">);

##</code><code>##

my ($sort_string) = grep { $_ =~ /^sort/ } @params;
my ($sort_field, $sort_dir)
    = defined($sort_string)
    ? $sort_string =~ /^sort:(\w+):(\w+)/
    : qw(avin desc);