+
+ my $out = '';
+ $out .= sprintf '<colgroup span=%d>', 3 * @{$_} for @colmap;
+ my $huerow = $colmap[0][0]; # first {$_} map { @{$_} } @colmap;
+ for my $h (grep { $huerow->[$_] } 0 .. $#{$huerow}) {
+ $out .= '<tr>';
+ $out .= colcell(@$_) for map { $_->[$h] } map { @{$_} } @colmap;
+ }
+
+ $offset += $dim ** 3;
+ $greymap{$offset++} = $_ for @{$greyramp};
+
+ $out .= '<tbody>';
+ my $col = 0;
+ my $colbreak = scalar map { @$_ } @colmap; # same width as hue rows
+ for my $num (sort { $greymap{$a} <=> $greymap{$b} } keys %greymap) {
+ $out .= '<tr>' unless $col++ % $colbreak;
+ $out .= colcell($num, ($greymap{$num}) x 3);
+ }
+
+ return $out;